TECHNICAL FIELD

The present disclosure relates to the field of material sciences. The present disclosure particularly relates to nanofiber comprising shellac and graphene, its preparation and to an article comprising said nanofiber.

BACKGROUND OF THE DISCLOSURE
Nanofibers are fibers with diameters in the nanometre range. Various materials have been used for constituting nanofibers, but most of the widely known materials for producing nanofibers are synthetic polymers.

From the point of view of use of nanofibers in the field of medical and compatibility of nanofibers with living organisms, natural polymer such as Shellac has been explored for producing nanofibers.

Ferulic acid (active agent) loaded shellac nanofiber and Monolaurin (antibiotic) loaded shellac nanofiber are reported for delivery of active agents. However, it was noted that shellac based nanofibers showed certain poor mechanical properties. In order to improve the mechanical properties of shellac based nanofibers, one of the research group has employed synthetic polymers like PVP. However, it was noted that use of 25 wt.% of the synthetic polymers with shellac for producing nanofibers didn’t improve the stretching property of the nanofibers. Therefore, they further increased the synthetic polymer (PVP) concentration to almost 75 wt.%, wherein they were able to improve the mechanical property of the nanofibers to some extent.

Further, it was noted that shellac based nanofibers had diameter in the micron range, as a result, it demonstrated reduced surface area. For the fabrication of shellac based nanofibers having diameter below 1 micron, two different techniques, i.e., single fluid electrospinning and modified coaxial electrospinning process were required, which was expensive and time consuming. Thus, making the preparation of shellac based nanofibers complex and not economical.

Thus, there is a need to arrive at nanofibers which overcomes all the disadvantages and limitations noted above for shellac-based nanofibers.

STATEMENT OF THE DISCLOSURE
Accordingly, the present disclosure relates to nanofiber comprising shellac and graphene having improved mechanical properties when compared to known shellac based nanofibers. The nanofiber of the present disclosure has diameter of less than or equal to 600 nm.

In an embodiment, the present disclosure relates to a process of preparing the nanofiber which is simple, cost effective, does not employ any harsh or toxic chemicals. Thus, making the process economical and environmentally friendly. Said process of preparing the nanofiber comprises- preparing a dispersion comprising graphene powder and shellac; and electrospinning the dispersion to obtain the nanofiber.

In an embodiment, the present disclosure relates to an article comprising said nanofiber comprising shellac and graphene. The article is selected from a group comprising filtration membrane, absorbent material, drug delivery system, wound healing bandage and face mask.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
In order that the present disclosure may be readily understood and put into practical effect, reference will now be made to exemplary embodiments as illustrated with reference to the accompanying figures. The figures together with detailed description below, are incorporated in and form part of the specification, and serve to further illustrate the embodiments and explain various principles and advantages, where:

FIGURE 1 illustrates a flow diagram depicting preparation of the nanofiber of the present disclosure and its application.

FIGURE 2 illustrates Scanning Electron microscope (SEM) image of pure shellac nanofiber (conventionally available) and nanofiber of the present disclosure, wherein- a) illustrates SEM image of pure shellac nanofiber; b) illustrates nanofiber comprising shellac and graphene ink on cotton fabric, wherein graphene ink is in an amount of about 1 wt.%; c) illustrates nanofiber comprising shellac and graphene ink on cotton fabric, wherein graphene ink is in an amount of about 1.5 wt.%; and d) illustrates nanofiber comprising shellac and graphene ink on cotton fabric, wherein graphene ink is in an amount of about 2 wt.%.

FIGURE 3 illustrates plot depicting contact angle of nanofiber of the present disclosure on paper and fabric in comparison with only paper, fabric and pure shellac (devoid of graphene)

FIGURE 4 illustrate antibacterial activity of the nanofiber of the present disclosure, wherein- a) illustrates antibacterial activity of the just the fabric (control); b) illustrates antibacterial activity of the nanofiber comprising 1% G-ink; c) illustrates antibacterial activity of the nanofiber comprising 1.5% G-ink; and d) illustrates antibacterial activity of the nanofiber comprising 2% G-ink.

FIGURE 5 illustrates Raman Spectra plot of the nanofiber of the present disclosure comprising graphene oxide and shellac.

DETAILED DESCRIPTION OF THE DISCLOSURE
Unless otherwise defined, all terms used in the disclosure, including technical and scientific terms, have meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. By means of further guidance, term definitions are included for better understanding of the present disclosure.

As used herein, the singular forms ‘a’, ‘an’ and ‘the’ include both singular and plural referents unless the context clearly dictates otherwise.

The term ‘comprising’, ‘comprises’ or ‘comprised of’ as used herein are synonymous with ‘including’, ‘includes’, ‘containing’ or ‘contains’ and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps.

The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within the respective ranges, as well as the recited endpoints.

The term ‘about’ as used herein when referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, is meant to encompass variations of ±10% or less, preferably ±5% or less, more preferably ±1% or less and still more preferably ±0.1% or less of and from the specified value, insofar such variations are appropriate to perform the present disclosure. It is to be understood that the value to which the modifier ‘about’ refers is itself also specifically, and preferably disclosed.

The present disclosure relates to nanofiber comprising graphene and shellac having improved mechanical properties when compared to known shellac based nanofibers.

In some embodiments of the present disclosure, the nanofiber shows antibacterial activity without presence of any antibiotics unlike the known shellac based nanofibers which mandatorily employ antibiotics in the nanofibers to impart antibacterial activity.

In some embodiments of the present disclosure, the nanofiber has diameter ranging from about 150 nm to 600 nm, including all the values in the range, for instance 151 nm, 152 nm, 153 nm, 154 and so on and so forth.

In some embodiments of the present disclosure, the nanofiber has diameter of less than or equal to 600 nm.

In some embodiments of the present disclosure, the graphene is selected from a group comprising graphene based ink (G-ink), graphene oxide and a combination thereof.

In some embodiments of the present disclosure, the shellac is dewaxed shellac. The dewaxed shellac means, shellac devoid of wax and is visibly clear in nature unlike waxed shellac which comprises wax and is cloudy or turbid in nature.

In some embodiments of the present disclosure, the nanofiber constitutes graphene in a range of about 0.1 % to 2%, including all the values in the range, for instance 0.2%, 0.3%, 0.4%, 0.5% and so on and so forth.

In some embodiments of the present disclosure, the nanofiber has surface resistivity ranging from about 108 ohms/sq to 1011 ohms/sq.

In some embodiments of the present disclosure, the nanofiber has surface resistivity of about 108 ohms/sq, about 109 ohms/sq, about 1010 ohms/sq or about 1011 ohms/sq.

In some embodiments of the present disclosure, the nanofiber has static water contact angle (?) ranging from about 100º to 140º, including all the values in the range, for instance 101º, 102º, 103º, 104º and so on and so forth.

In an embodiment of the present disclosure, Figure 3 illustrates a plot depicting contact angle (?) of the nanofiber on paper and fabric in comparison with the contact angle (?) of only paper and shellac nanofiber without graphene (GSNF-0). The data in figure 3 establishes that the nanofiber of the present disclosure (GSNF-1, GSNF-1.5, GSNF-2) has increased contact angle (?) when compared to shellac nanofiber without graphene (GSNF-0). Increased contact angle (?) demonstrated by the nanofibers of the present disclosure shows improved hydrophobicity when compared to shellac nanofibers without graphene.

In some embodiments of the present disclosure, the nanofiber exhibits antibacterial activity. Antibacterial effect of the nanofiber of the present disclosure is achieved without use of antibiotics in the nanofiber.

In an embodiment of the present disclosure, Figure 4 illustrates antibacterial activity of the nanofiber of the present disclosure against Gram-positive bacteria Staphylococcus aureus ATCC 6538 and Gram-negative bacterial Klebsiella pneumonia ATCC 4352.

In some embodiments of the present disclosure, the nanofiber possesses improved antistatic property.

In some embodiments of the present disclosure, the nanofiber is uniform, continuous and smooth in nature, devoid of beads or with negligible beads.

In some embodiments of the present disclosure, the nanofiber is biodegradable.

In some embodiments of the present disclosure, the nanofiber possesses improved flexibility when compared to shellac based nanofibers devoid of graphene.

In some embodiments of the present disclosure, the nanofiber has improved surface area.

In some embodiments of the present disclosure, the nanofiber has improved porosity.

In some embodiments of the present disclosure, the nanofiber has improved permeability, as a result, provides for improved exchange of gases.

In some embodiments of the present disclosure, the nanofiber has improved tensile strength

The present disclosure further relates to process of preparing the nanofiber described above.

In an embodiment of the present disclosure, the process of preparing the nanofiber is simple, cost effective and environmentally friendly.

In some embodiments of the present disclosure, the process of preparing the nanofiber comprises:
- Preparing a dispersion comprising graphene and shellac; and
- Electrospinning the dispersion to obtain the nanofiber.

In some embodiments of the present disclosure, preparing the dispersion comprising graphene and shellac comprises:
- Mixing graphene oxide with a solution of dewaxed shellac; or
- Mixing graphene based ink with a solution of dewaxed shellac.

In some embodiments of the present disclosure, the process of preparing dispersion comprising graphene and shellac comprises- mixing graphene oxide with a solution of dewaxed shellac.

In some embodiments of the present disclosure, the mixing of the graphene oxide with the solution of dewaxed shellac comprises stirring for a duration ranging from about 200 rpm to 500 rpm, including all the values in the range, for instance 201 rpm, 202 rpm, 203 rpm, 204 rpm and so on and so forth, followed by sonicating for a duration ranging from about 10 minutes to 30 minutes, including all the values in the range, for instance 11 minutes, 12 minutes, 13 minutes, 14 minutes and so on and so forth.

In some embodiments of the present disclosure, the graphene oxide is at a concentration ranging from about 0.1% w/v to 2% w/v, including all the values in the range, for instance 0.2% w/v, 0.3% w/v, 0.4% w/v, 0.5% w/v and so on and so forth.

In some embodiments of the present disclosure, the process of preparing dispersion comprising graphene and shellac comprises- mixing graphene based ink with a solution of dewaxed shellac.

In some embodiments of the present disclosure, the mixing of the graphene based ink with the solution of dewaxed shellac comprises stirring for a duration ranging from about 300 rpm to 400 rpm, including all the values in the range, for instance 301 rpm, 302 rpm, 303 rpm, 304 rpm and so on and so forth, followed by sonicating for a duration ranging from about 10 minutes to 20 minutes, including all the values in the range, for instance 11 minutes, 12 minutes, 13 minutes, 14 minutes and so on and so forth.
In some embodiments of the present disclosure, the graphene based ink is at a concentration ranging from about 0.1% w/v to 2% w/v, including all the values in the range, for instance 0.2% w/v, 0.3% w/v, 0.4 w/v, 0.5 w/v and so on and so forth.

In some embodiments of the present disclosure, the graphene based ink is prepared by dispersing graphene into a blend comprising binder and solvent, followed by stirring for a duration ranging from about 30 minutes to 60 minutes, including all the values in the range, for instance 31 minutes, 32 minutes, 33 minutes, 34 minutes and so on and so forth and sonication for a duration ranging from about 1 hour to 3 hours, including all the values in the range, for instance 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours and so on and so forth.

In some embodiments of the present disclosure, the binder is selected from a group comprising ethyl cellulose, cellulose ester, nitrocellulose, phenolic resin, polyester resin, carboxymethyl cellulose and any combination thereof.

In some embodiments of the present disclosure, the solvent is selected from a group comprising ethanol, isopropyl alcohol, toluene, acetone, dimethyl formamide, methanol, ethyl acetate and any combination thereof.

In some embodiments of the present disclosure, the graphene is at a concentration ranging from about 1 wt% to 20 wt%, including all the values in the range, for instance 1.1 wt% 1.2 wt%, 1.3 wt%, 1.4 wt% and so on and so forth.

In some embodiments of the present disclosure, the binder is at a concentration ranging from about 30 wt% to 50 wt%, including all the values in the range, for instance 30.1 wt%, 30.2 wt%, 30.3 wt%, 30.4 wt% and so on and so forth.

In some embodiments of the present disclosure, the solvent is at a concentration ranging from about 40 wt% to 60 wt%, including all the values in the range, for instance 40.1 wt%, 40.2 wt%, 40.3 wt%, 40.4 wt% and so on and so forth.

In some embodiments of the present disclosure, the dewaxed shellac solution is prepared by dissolving dewaxed shellac in a solvent selected from a group comprising isopropyl alcohol, ethanol, dimethylformamide and combination thereof, followed by heating to a temperature ranging from about 60 ºC to 90 ºC , including all the values in the range for instance 61 ºC, 62 ºC, 63 ºC, 64 ºC and so on and so forth and stirring at a rotational speed ranging from about 200 rpm to 500 rpm, including all the values in the range, for instance 201 rpm, 202 rpm, 203 rpm, 204 rpm and so on and so forth.

In some embodiments of the present disclosure, the electrospinning of the dispersion is carried out at a voltage ranging from about 10 KV to 20 KV, including all the values in the range, for instance 10.1 KV, 10.2 KV, 10.3 KV, 10.4 KV and so on and so forth.

In some embodiments of the present disclosure, flow rate of the dispersion during electrospinning is ranging from about 0.5 mL/hr to 1.5 mL/hr, including all the values in the range, for instance 0.6 mL/hr, 0.7 mL/hr, 0.8 mL/hr, 0.9 mL/hr and so on and so forth.

In some embodiments of the present disclosure, the electrospinning is carried out at a rotating speed ranging from about 150 rpm to 500 rpm, including all the values in the range, for instance 151 rpm, 152 rpm, 153 rpm, 154 rpm and so on and so forth.

In some embodiments of the present disclosure, during electrospinning, the distance between needle and collector in an electrospinning apparatus/equipment is ranging from about 8 cm to 12 cm, including all the values in the range, for instance 8.1 cm, 8.2 cm, 8.3 cm, 8.4 cm and so on and so forth.

In some embodiments of the present disclosure, the nanofiber is prepared on a substrate selected from a group comprising cellulosic paper, natural fabric, including but not limited to cotton, metal foil, including but not limited to aluminium foil, nonwoven synthetic fabric, including but not limited to polypropylene sheet.

The present disclosure further relates to an article comprising the nanofiber described above.

In some embodiments of the present disclosure, the article is selected from a group comprising filtration membrane, absorbent material, drug delivery system, would healing bandages and face mask.

In some embodiments of the present disclosure, the filtration membrane is selected from a group comprising air filtration membrane and water filtration membrane.
In some embodiments of the present disclosure, the filtration membrane prepared from the nanofiber described above provides- air filtration against dust, dirt, soot, smoke, airborne pathogen including but not limited to S. aureus and S. pneumoniae; water filtration against waterborne pathogen including but not limited to E. Coli and Salmonella typhi; and absorbent of volatile organic materials.

In some embodiments of the present disclosure, the filtration membrane prepared from the nanofiber described above in the form of mask prevent pathogens including but not limited to bacteria and viruses.

In some embodiments of the present disclosure, the article comprising the nanofiber described above can be employed in applications including but not limited to drug delivery and tissue engineering.

In an embodiment of the present disclosure, figure 1 describes a flow diagram representing process of preparation of the nanofiber, characterization of the nanofiber and applications of the nanofiber.

In an embodiment of the present disclosure, figure 5 illustrates Raman spectra of nanofiber comprising graphene oxide and shellac. The plot shows successful incorporation of graphene oxide in the nanofibers.

The present disclosure provides for the following advantages-
- Dispersion of the graphene including but not limited to graphene oxide and graphene based ink in the shellac solution provided continuous and smooth nanofiber at a voltage (10 KV to 20 KV) less than the voltage applied conventionally during electrospinning of nanofibers.
- Dispersion of graphene including but not limited to graphene oxide and graphene based ink in shellac solution increased stretching ability of the nanofibers. As a result, the nanofibers have improved flexibility when compared to conventionally known shellac based nanofibers.
- The nanofibers are easily removable from the substrate on which the nanofibers are formed/obtained. Thus, proving that the nanofibers have improved mechanical strength and flexibility.
- Uniform and continuous nanofibers are obtained devoid of beads or with negligible beads.
- The nanofibers are biodegradable in nature.
- Diameter of the nanofiber is ranging from about 150 nm to 600 nm which is significantly lesser when compared to the diameter of the conventionally known shellac based nanofibers.
- The nanofiber exhibits antibacterial activity without employing any antibiotics unlike the conventionally known shellac based nanofibers.
- The process of preparing the nanofiber does not employ harsh chemicals but employs only green solvent (environmentally friendly solvent).
- Employing dewaxed shellac overcame the limitations noted during electrospinning.
- Employing dewaxed shellac at a concentration ranging from 10 % w/v to 70% w/v and during electrospinning, employing voltage in a range of about 10 KV to 20 KV and maintaining distance between needle and collector in the electrospinning apparatus in a range of about 8 cm to 12 cm, led to preparation of continuous and uniform nanofibers devoid of beads or with negligible beads.

It is to be understood that the foregoing description is illustrative not a limitation. While considerable emphasis has been placed herein on particular features of this disclosure, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. Those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein. Similarly, additional embodiments and features of the present disclosure will be apparent to one of ordinary skill in art based upon description provided herein.

Descriptions of well-known/conventional methods/steps and techniques are omitted so as to not unnecessarily obscure the embodiments herein. Further, the disclosure herein provides for examples illustrating the above-described embodiments, and in order to illustrate the embodiments of the present disclosure, certain aspects have been employed. The examples used herein for such illustration are intended merely to facilitate an understanding of ways in which the embodiments may be practiced and to further enable those of skill in the art to practice the embodiments. Accordingly, following examples should not be construed as limiting the scope of the embodiments herein.

EXAMPLES

EXAMPLE 1: Preparation of Graphene ink (G-Ink)
i. Binder preparation: Ethyl cellulose was mixed with solvent (Ethanol) in ratio of about 1:9. The mixer was heated at temperature of about 70 ºC with stirring for about 6 hours.
ii. G-Ink preparation: about 20 g of binder and about 30 g of ethanol was taken in blending pot. Blending was carried out for about 3 times, then about 2 g of graphene powder was added into it. Then blending was carried out for about 15 times, 20 seconds each. Further, it was subjected to sonication for a duration of about 2 hours during which about 0.5 gm of Byk190 was added into it. Thereafter, probe sonication was carried out for about1 hour in 8 hours.

EXAMPLE 2: Preparation of nanofiber with 1% Graphene based Ink (G-Ink)
About 70 g of Shellac was taken and dispersed in about 100 mL of isopropyl alcohol (IPA) with constant heating at a temperature of about 80 °C and stirring at about 300 rpm till a clear dispersion was achieved approximately in 8 hours to obtain shellac solution.
About 1 g of G-Ink was taken and added in about 100 mL of Shellac solution for preparation of 1w/v% G-Ink doped Shellac solution. The mixture was stirred further for about 30 minutes in order to have a proper dispersion. The above mixture was sonicated in a probe sonication for about 15 minutes to promote complete mixing. Then sample was loaded in about 5ml of plastic syringe for electrospinning. Parameters employed during electrospinning were- voltage of about 18 KV, rotating speed of about 300 rpm, distance between syringe and collector in the electrospinning apparatus of about 8 cm, flow rate of about 1.2 mL/hr. Substrate used for collection of nanofibers was poplin fabrics (cotton fabric). The obtained nanofibers were characterized through SEM, Contact angle, Antibacterial test 147 and Surface resistivity.
i. Surface resistivity meter was employed to check the resistivity.
ii. Contact angle measurement meter was employed to measure the contact angle (?).
iii. Antibacterial test was carried out using AATCC:147. The test organisms were Staphylococcus aureus ATCC 6538 and Klebsiella pneumoniae ATCC 4352. Sample nanofibers taken were circular swatches of 4.8 ± 0.1 cm in diameter. Volume of test inoculum was 1 ml. Media used were Nutrient Broth and Nutrient Agar. Incubation done at 37 ºC for 24 hours.
Characterization details are provided in table 1.
CHARACTERIZATION RESULTS
SEM 350-600 nm
CONTACT ANGLE Approx. 129.05º
SURFACE RESISTIVITY 10¹² ohms/sq
ANTIBACTERIAL ACTIVITY Present
Table 1:

EXAMPLE 3: Preparation of nanofibers with 1.5% Graphene based Ink (G-Ink)
About 70 g of Shellac was taken and dispersed in about 100 mL of isopropyl alcohol (IPA) with constant heating at a temperature of about 80 °C and stirring at about 300 rpm till a clear dispersion was achieved approximately in 8 hours to obtain shellac solution.
About 1.5 g of G-Ink was taken and added in about 100 mL of Shellac solution for preparation of 1.5 w/v% G-Ink doped Shellac solution. The mixture was stirred further for about 30 minutes in order to have a proper dispersion. The above mixture was sonicated in a probe sonication for about 15 minutes to promote complete mixing. Then sample was loaded in about 5ml of plastic syringe for electrospinning. Parameters employed during electrospinning were- voltage of about 18 KV, rotating speed of about 300 rpm, distance between syringe and collector in the electrospinning apparatus of about 8 cm, flow rate of about 1.2 mL/hr. Substrate used for collection of nanofibers was poplin fabrics (cotton fabric). The obtained nanofibers were characterized through SEM, Contact angle, Antibacterial test 147 and Surface resistivity.
i. Surface resistivity meter was employed to check the resistivity.
ii. Contact angle measurement meter was employed to measure the contact angle (?).
iii. Antibacterial test was carried out using AATCC:147. The test organisms were Staphylococcus aureus ATCC 6538 and Klebsiella pneumoniae ATCC 4352. Sample nanofibers taken were circular swatches of 4.8 ± 0.1 cm in diameter. Volume of test inoculum was 1 ml. Media used were Nutrient Broth and Nutrient Agar. Incubation done at 37 ºC for 24 hours.
Characterization details are provided in table 2.
CHARACTERIZATION RESULTS
SEM 300-500 nm
CONTACT ANGLE Approx. 134.05º
SURFACE RESISTIVITY 10¹¹ ohms/sq
ANTIBACTERIAL ACTIVITY Present
Table 2:

EXAMPLE 4: Preparation of nanofibers with 2 % Graphene based Ink (G-ink)
About 70 g of Shellac was taken and dispersed in about 100 mL of isopropyl alcohol (IPA) with constant heating at a temperature of about 80 °C and stirring at about 300 rpm till a clear dispersion was achieved approximately in 8 hours to obtain shellac solution.
About 2 g of G-Ink was taken and added in about 100 mL of Shellac solution for preparation of 2 w/v% G-Ink doped Shellac solution. The mixture was stirred further for about 30 minutes in order to have a proper dispersion. The above mixture was sonicated in a probe sonication for about 15 minutes to promote complete mixing. Then sample was loaded in about 5ml of plastic syringe for electrospinning. Parameters employed during electrospinning were- voltage of about 18 KV, rotating speed of about 300 rpm, distance between syringe and collector in the electrospinning apparatus of about 8 cm, flow rate of about 1.2 mL/hr. Substrate used for collection of nanofibers was poplin fabrics (cotton fabric). The obtained nanofibers were characterized through SEM, Contact angle, Antibacterial test 147 and Surface resistivity.
i. Surface resistivity meter was employed to check the resistivity.
ii. Contact angle measurement meter was employed to measure the contact angle (?).
iii. Antibacterial test was carried out using AATCC:147. The test organisms were Staphylococcus aureus ATCC 6538 and Klebsiella pneumoniae ATCC 4352. Sample nanofibers taken were circular swatches of 4.8 ± 0.1 cm in diameter. Volume of test inoculum was 1 ml. Media used were Nutrient Broth and Nutrient Agar. Incubation done at 37 ºC for 24 hours.

Characterization details are provided in table 3.
CHARACTERIZATION RESULTS
SEM 280 - 500 nm
CONTACT ANGLE Approx. 135.02º
SURFACE RESISTIVITY 10¹¹ ohms/sq
ANTIBACTERIAL ACTIVITY Present
Table 3:

EXAMPLE 5: Preparation of nanofibers with 1% Graphene oxide
About 70 g of Shellac was taken and dispersed in about 100 mL of isopropyl alcohol (IPA) with constant heating at a temperature of about 80 °C and stirring at about 300 rpm till a clear dispersion was achieved approximately in 8 hours to obtain shellac solution.
About 1 g of graphene oxide (GO) was taken and added in about 100 mL of Shellac solution for preparation of 1w/v% GO doped Shellac solution. The mixture was stirred further for about 30 minutes in order to have a proper dispersion. The above mixture was sonicated in a probe sonication for about 15 minutes to promote complete mixing. Then sample was loaded in about 5ml of plastic syringe for electrospinning. Parameters employed during electrospinning were- voltage of about 18 KV, rotating speed of about 500 rpm, distance between syringe and collector in the electrospinning apparatus of about 8 cm, flow rate of about 1.2 mL/hr. Substrate used for collection of nanofibers was aluminium foil. The obtained nanofibers were characterized through SEM, Contact angle, Antibacterial test 147 and Surface resistivity.
i. Surface resistivity meter was employed to check the resistivity.
ii. Contact angle measurement meter was employed to measure the contact angle (?).
iii. Antibacterial test was carried out using AATCC:147. The test organisms were Staphylococcus aureus ATCC 6538 and Klebsiella pneumoniae ATCC 4352. Sample nanofibers taken were circular swatches of 4.8 ± 0.1 cm in diameter. Volume of test inoculum was 1 ml. Media used were Nutrient Broth and Nutrient Agar. Incubation done at 37 ºC for 24 hours.
Characterization details are provided in table 4.
CHARACTERIZATION RESULTS
SEM 600 nm – 1µ
CONTACT ANGLE Approx. 132.18°
SURFACE RESISTIVITY 10? ohm/sq
ANTIBACTERIAL ACTIVITY Present
Table 4:

EXAMPLE 6: Preparation of nanofibers with 1.5% Graphene oxide
About 70 g of Shellac was taken and dispersed in about 100 mL of isopropyl alcohol (IPA) with constant heating at a temperature of about 80 °C and stirring at about 300 rpm till a clear dispersion was achieved approximately in 8 hours to obtain shellac solution.
About 1.5 g of graphene oxide (GO) was taken and added in about 100 mL of Shellac solution for preparation of 1.5 w/v% GO doped Shellac solution. The mixture was stirred further for about 30 minutes in order to have a proper dispersion. The above mixture was sonicated in a probe sonication for about 15 minutes to promote complete mixing. Then sample was loaded in about 5ml of plastic syringe for electrospinning. Parameters employed during electrospinning were- voltage of about 18 KV, rotating speed of about 500 rpm, distance between syringe and collector in the electrospinning apparatus of about 8 cm, flow rate of about 1.2 mL/hr. Substrate used for collection of nanofibers was aluminium foil. The obtained nanofibers were characterized through SEM, Contact angle, Antibacterial test 147 and Surface resistivity.
i. Surface resistivity meter was employed to check the resistivity.
ii. Contact angle measurement meter was employed to measure the contact angle (?).
iii. Antibacterial test was carried out using AATCC:147. The test organisms were Staphylococcus aureus ATCC 6538 and Klebsiella pneumoniae ATCC 4352. Sample nanofibers taken were circular swatches of 4.8 ± 0.1 cm in diameter. Volume of test inoculum was 1 ml. Media used were Nutrient Broth and Nutrient Agar. Incubation done at 37 ºC for 24 hours.

EXAMPLE 7: Preparation of nanofibers with 2% Graphene oxide
About 70 g of Shellac was taken and dispersed in about 100 mL of isopropyl alcohol (IPA) with constant heating at a temperature of about 80 °C and stirring at about 300 rpm till a clear dispersion was achieved approximately in 8 hours to obtain shellac solution.
About 2 g of graphene oxide (GO) was taken and added in about 100 mL of Shellac solution for preparation of 2 w/v% GO doped Shellac solution. The mixture was stirred further for about 30 minutes in order to have a proper dispersion. The above mixture was sonicated in a probe sonication for about 15 minutes to promote complete mixing. Then sample was loaded in about 5ml of plastic syringe for electrospinning. Parameters employed during electrospinning were- voltage of about 18 KV, rotating speed of about 500 rpm, distance between syringe and collector in the electrospinning apparatus of about 8 cm, flow rate of about 1.2 mL/hr. Substrate used for collection of nanofibers was aluminium foil. The obtained nanofibers were characterized through SEM, Contact angle, Antibacterial test 147 and Surface resistivity.
i. Surface resistivity meter was employed to check the resistivity.
ii. Contact angle measurement meter was employed to measure the contact angle (?).
iii. Antibacterial test was carried out using AATCC:147. The test organisms were Staphylococcus aureus ATCC 6538 and Klebsiella pneumoniae ATCC 4352. Sample nanofibers taken were circular swatches of 4.8 ± 0.1 cm in diameter. Volume of test inoculum was 1 ml. Media used were Nutrient Broth and Nutrient Agar. Incubation done at 37 ºC for 24 hours.

EXAMPLE 8: Preparation of nanofibers with 1% Graphene based Ink (G-Ink)
About 70 g of Shellac was taken and dispersed in about 100 mL of isopropyl alcohol (IPA) with constant heating at a temperature of about 80 °C and stirring at about 300 rpm till a clear dispersion was achieved approximately in 8 hours to obtain shellac solution.
About 1 g of G-Ink was taken and added in about 100 mL of Shellac solution for preparation of 1w/v% G-Ink doped Shellac solution. The mixture was stirred further for about 30 minutes in order to have a proper dispersion. The above mixture was sonicated in a probe sonication for about 15 minutes to promote complete mixing. Then sample was loaded in about 5ml of plastic syringe for electrospinning. Parameters employed during electrospinning were- voltage of about 18 KV, rotating speed of about 300 rpm, distance between syringe and collector in the electrospinning apparatus of about 8 cm, flow rate of about 1.2 mL/hr. Substrate used for collection of nanofibers was paper. The obtained nanofibers were characterized through SEM, Contact angle, Antibacterial test 147 and Surface resistivity.
i. Surface resistivity meter was employed to check the resistivity.
ii. Contact angle measurement meter was employed to measure the contact angle (?).
iii. Antibacterial test was carried out using AATCC:147. The test organisms were Staphylococcus aureus ATCC 6538 and Klebsiella pneumoniae ATCC 4352. Sample nanofibers taken were circular swatches of 4.8 ± 0.1 cm in diameter. Volume of test inoculum was 1 ml. Media used were Nutrient Broth and Nutrient Agar. Incubation done at 37 ºC for 24 hours.
Characterization details are provided in table 5.
CHARACTERIZATION RESULTS
SEM 250-500 nm
CONTACT ANGLE Approx. 129.05º
SURFACE RESISTIVITY 10¹² ohms/sq
ANTIBACTERIAL ACTIVITY Present
Table 5:

The data in Table 6 provides antimicrobial activity of the nanofiber.
Sample code Test Organism No. of Bacteria per sample (CPU Sample) at Percentage Reduction of Bacteria (R)
0 ‘Hrs’ (C) 24 ‘Hrs’ (A) --
Viability control fabrics Staphylococcus aureus 1.65 x 105 7.95 x 106 --
Klebsiella pneumoniae 2.17 x 105 9.50 x 106
GSNF 0 Uninoculated 0 ¬¬-- ¬¬--
Staphylococcus aureus 1.70 x 105 <10 99.99%
Klebsiella pneumoniae 2.01 x 105 5.75 x 104 71.39%
GSNF 2 Uninoculated 0 ¬¬-- --
Staphylococcus aureus 2.08 x 105 <10 99.99%
Klebsiella pneumoniae 1.91 x 105 1.66 x 104 91.30%
Note: Percentage Reduction of Microorganism (R) = 100 (C-A)/C

Table 6: Evaluation of Antimicrobial Activity by Quantitative method AATCC 100-2019

The foregoing description of the specific embodiments reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments in this disclosure have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Throughout this specification, the term ‘combinations thereof’ or ‘any combination thereof’ or ‘any combinations thereof’ are used interchangeably and are intended to have the same meaning, as regularly known in the field of patents disclosures.

As regards the embodiments characterized in this specification, it is intended that each embodiment be read independently as well as in combination with another embodiment. For example, in case of an embodiment 1 reciting 3 alternatives A, B and C, an embodiment 2 reciting 3 alternatives D, E and F and an embodiment 3 reciting 3 alternatives G, H and I, it is to be understood that the specification unambiguously discloses embodiments corresponding to combinations A, D, G; A, D, H; A, D, I; A, E, G; A, E, H; A, E, I; A, F, G; A, F, H; A, F, I; B, D, G; B, D, H; B, D, I; B, E, G; B, E, H; B, E, I; B, F, G; B, F, H; B, F, I; C, D, G; C, D, H; C, D, I; C, E, G; C, E, H; C, E, I; C, F, G; C, F, H; C, F, I, unless specifically mentioned otherwise.

Any discussion of documents, acts, materials, devices, articles and the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.

Claims:WE CLAIM:
1. A nanofiber comprising shellac and graphene.

2. The nanofiber as claimed in claim 1, wherein the nanofiber has diameter ranging from about 150 nm to 600 nm.

3. The nanofiber as claimed in claim 1, wherein the nanofiber constitutes graphene in range of about 0.1% to 2%.

4. The nanofiber as claimed in claim 1, wherein the graphene is selected from a group comprising graphene-based ink (G-Ink), graphene oxide and a combination thereof.

5. The nanofiber as claimed in claim 1, wherein the shellac is dewaxed shellac.

6. The nanofiber as claimed in claim 1, wherein the nanofiber has surface resistivity ranging from about 108 ohms/sq to 1011 ohms/sq.

7. The nanofiber as claimed in claim 1, wherein the nanofiber has static water contact angle (?) ranging from about 100º to 140º.

8. The nanofiber as claimed in claim 1, wherein the nanofiber exhibits antibacterial activity.

9. A process for preparing the nanofiber as claimed in claim 1, said process comprises:
- preparing a dispersion comprising graphene and shellac; and
- electrospinning the dispersion to obtain the nanofiber.

10. The process as claimed in claim 9, wherein preparing the dispersion comprising graphene powder and shellac comprises:
- mixing graphene oxide with a solution of dewaxed shellac; or
- mixing graphene-based ink with a solution of dewaxed shellac.

11. The process as claimed in claim 10, wherein the mixing of the graphene oxide with the solution of the dewaxed shellac comprises stirring for a duration ranging from about 200 rpm to 500 rpm, followed by sonicating for a duration ranging from about 10 minutes to 30 minutes.

12. The process as claimed in claim 10, wherein the mixing of the graphene-based ink with the solution of the dewaxed shellac comprises stirring for a duration ranging from about 300 rpm to 400 rpm, followed by sonicating for a duration ranging from about 10 minutes to 20 minutes.

13. The process as claimed in claim 10, wherein the graphene oxide is at a concentration ranging from about 0.1% w/v to 2 % w/v.

14. The process as claimed in claim 10, wherein the graphene-based ink is at a concentration ranging from about 0.1% w/v to 2% w/v.

15. The process as claimed in claim 10, wherein the dewaxed shellac solution is prepared by dissolving dewaxed shellac into a solvent selected from a group comprising isopropyl alcohol, ethanol, dimethylformamide, and any combination thereof, followed by heating to a temperature ranging from about 60 °C to 90 °C and stirring at a rotational speed ranging from about 200 rpm to 500 rpm.

16. The process as claimed in claim 10, wherein the dewaxed shellac solution is at a concentration ranging from about 10 w/v% to 70 w/v%.

17. The process as claimed in claim 10, wherein the graphene based ink is prepared by dispersing graphene into a blend comprising binder and solvent, followed by stirring for a duration ranging from about 30 minutes to 60 minutes and sonication for a duration ranging from about 1hour to 3hours.

18. The process as claimed in claim 17, wherein the graphene is at a concentration ranging from about 1 wt% to 20 wt% to; the binder is at a concentration ranging from about 30 wt% to 50 wt%and the solvent is at a concentration ranging from about 40 wt% to 60 wt%.

19. The process as claimed in claim 17, wherein the binder is selected from a group comprising ethyl cellulose, cellulose ester, nitrocellulose, phenolic resin, polyester resins, and carboxymethyl cellulose and the solvent is selected from a group comprising ethanol, isopropyl alcohol, toluene, acetone, dimethylformamide, methanol, ethyl acetate.
20. The process as claimed in claim 9, wherein the electrospinning of the dispersion was carried out at a voltage ranging from about 10 KV to 20KV.

21. The process as claimed in claim 9, wherein flow rate of the dispersion during electrospinning is ranging from about 0.5 mL/hr to 1.5 mL/hr.

22. The process as claimed in claim 9, wherein the electrospinning is carried out at a rotating speed ranging from about 150 rpm to 500 rpm.

23. The process as claimed in claim 9, wherein distance between needle and collector in the electrospinning is ranging from about 8 cm to 12 cm.

24. The process as claimed in claim 9, wherein the nanofiber is prepared on a substrate selected from a group comprising cellulosic paper, natural fabrics, metal foils, nonwoven synthetic fabrics.

25. An article comprising the nanofiber as claimed in claim 1.

26. The article as claimed in claim 25, wherein the article is selected from a group comprising filtration membrane, absorbent material, drug delivery system, wound healing bandages and face mask.

27. The article as claimed in claim 26, wherein the filtration membrane is selected from a group comprising air filtration membrane and water filtration membrane.