Description:Field of invention:
[0001] By employing Carissa carandas bark extract as a reducing and capping agent in green biosynthesis, we extend this conventional application to produce CoFe2O4 and CoFe2O4@Ag nanocomposite. Various techniques have been used to analyse the synthesised nanocomposite, including UV-Vis, FTIR, XRD, FESEM, E.D.X., and B.E.T. The CoFe2O4 and CoFe2O4@Ag nanocomposite demonstrated promising antibacterial action against human bacterial pathogens like B. subtilis and S. aureus as gram positive and P. aeruginosa and E. coli as gram-negative with inhibition zones of 24.3 ± 0.57, 17.4 ± 0.75 and 20.5 ± 0.5, 19.8 ± 1.6 mm respectively, and the obtained results were superior to the catalyst without silver. The human breast cancer cell MCF-7, the in vitro cytotoxicity effects of biosynthesized CoFe2O4 and CoFe2O4@Ag were examined. The MCF-7 cells' 50% inhibitory concentration (IC50) was 60 µg/mL. Additionally, biosynthesized CoFe2O4 and CoFe2O4@Ag nanocomposite demonstrated the photocatalytic eradication of Rhodamine Blue (RhB). Due to the addition of Ag, which increases surface area, conductivity, and charge carrier separation, the CoFe2O4@Ag nanocomposite exhibits a high percentage of photocatalytic degradation of ? 98% within 35 min under U.V. light irradiation. Consequently, it is anticipated that the CoFe2O4@Ag nanocomposite will be a promising photocatalyst and possibly a noble material for environmental remediation applications.
Background of invention:
[002] Pollution is one of the biggest issues facing developing nations [1, 2]. This issue is exacerbated by pollutants leading to massive water contamination that depletes quantity and quality, including industrial effluent with dyestuff and heavy metal traces[3]. Without being treated, the wastewater of various companies discharges 5 tonnes of organic compounds annually, damaging freshwater resources [4]. Many dangerous human diseases are thought to have been brought on by this contaminated/unhealthy water [5]. In addition to the paper, plastic, printing, and leather sectors, the textile industry regularly uses rhodamine B (RhB) to colour woollen materials. It is frequently employed in biomedical research as a colorant, photosensitizer, water tracer, and fluorescent marker. It has been widely reported that RhB, which is illegal and may cause cancer, can be found in various foods, including chilli powder, preserved plums, sausage, and sweets [6]. RhB can harm aquatic creatures' reproductive and respiratory systems, cause tissue necrosis, and even cause cancer at low concentrations [7, 8]. As a result, any method for recovering water from wastewater is closely scrutinized by scientists to lessen any adverse environmental effects. Several techniques, such as chemical precipitation, biological treatment, adsorption, sonochemical, membrane processes, and membrane filtration, are available to effectively remove such pollutants and recover water from wastewater [9-11]. The fact that dyes contain aromatic rings and are biochemically durable renders conventional methods for dye degradation ineffective [12]. We adopted a distinct, inexpensive and very effective strategy because other procedures require expensive apparatus and have slow purifying rates [13].
[003] On the other hand, pathogenic bacteria found in wastewater have the potential to impact ecosystems and public health significantly. Escherichia coli (E. coli), Salmonella, Vibrio cholera (causes cholera), and Cryptosporidium (causes cryptosporidiosis) are common waterborne pathogens that can disrupt ecosystems, contaminate water, and transmit diseases like gastroenteritis, pneumonia, skin and soft tissue infections, and other waterborne illnesses. Further, pathogenic bacteria present in wastewater can contribute to developing and spreading antibiotic-resistant strains. This resistance can also spread to bacteria that infect humans, making it more difficult to treat diseases successfully and leading to the emergence of environmental persistence cultures. Implementing efficient wastewater treatment procedures to eliminate or inactivate pathogenic bacteria before releasing water into the environment is crucial to reducing these effects [14].
[004]Our research focuses on nanomaterials, which differ from their macro-scale counterparts in several ways due to their numerous innovative features, including low volume-to-surface ratio and particular physio-chemical characteristics like thermodynamic, toxicity, colour, optical solubility, magnetic, strength, and prevalence properties [15]. It is well known that iron-based bimetallic nanoparticles can be used to remove pollutants from contaminated water [16]. In this system, noble metals or transition metals like nickel, palladium, and silver act as catalysts, while iron-based metal oxide nanoparticles (Fe-NPs) act as reductants [17]. In contrast to physicochemical methods, non-toxic, cost-effective, and environmentally friendly biological approaches have recently gained much attention [18]. Several methods have been discovered for the natural or physiological formulation of nanomaterials from the salts of different metal ions. Leveraging plants offers an advantage over other biological synthetic techniques since it eliminates the need for time-consuming fungal and bacterial culture and preserving techniques. [19]. Additionally, exogenous plant extracts were more skillful and effective at controlling nanoparticle dimension, form, and dispersion [19]. Consequently, Carissa carandas, also known as karonda, is an apocynaceous (family: Apocynaceae) prickly evergreen shrub. It is a water-stressed plant that can flourish in several types of soil. Five of the approximately 25 species in the Carissa family are indigenous to India [20]. According to study, the Carissa carandas fruit is the best source of iron, vitamin C, pectin, and flavonoids[20]. The plant is in high demand on the market due to its antiscorbutic properties and beneficial benefits in the treatment of anaemia [21]. Greenly manufactured iron-oxide-based nanoparticles are less hazardous, more eco-friendly, and have promising biological properties [22]. To treat various illnesses, including cancer, microbial infections, and antioxidant therapy, biosynthesized iron-oxide and modified nanocomposites have shown outstanding catalytic potentials [23]. One of the most significant and extensively studied groups of magnetic nanoparticles is cobalt ferrite (CoFe2O4). It is ideal for use in a variety of applications due to its unique physical, chemical, mechanical, electrical, and electrochemical properties, including an array of redox states, outstanding chemical durability, more effective electrochemical strength, ease of synthesis, mild saturation magnetism, a substantial anisotropy constant, and a highly magnetostrictive. On the other hand, when cobalt ferrite is combined with noble metals like Ag and Au, it acquires better properties. Given that Ag is naturally antimicrobial, it makes sense that adding Ag to CoFe2O4 will boost its antibacterial and catalytic properties. To date various plant based materials such as A. esculentus plant extract, Hibiscus rosa-sinensis extract, cardamom seed extracts, Nephelium lappaceum L. peel extract, Aloe vera plant extract, Sesamum indicum L. seeds extract, Salix alba bark extract, tamarind extract, and Moringa oleifera leaf extract were used to create CoFe2O4 and CoFe2O4 hybrid nanocomposites [24].
[005] For the first time, CoFe2O4 and CoFe2O4@Ag hybrid nanocomposites were created using an aqueous extract of Carissa carandas and their multifunctional capabilities were investigated. Next, whether biosynthesized CoFe2O4 and CoFe2O4@Ag nanocomposites were toxic to human breast cancer cell lines MCF-7 was determined. The photocatalytic process's efficiency in photodegrading RhB under UV light and its antibacterial activity against bacterial infections were investigated.
The objective of invention:
[006] The main object of the embodiments herein is to biogenic synthesis of CoFe2O4 and CoFe2O4@Ag nanocomposites from Carissa Carandas plant.
[007] Another object of the embodiments herein is the biogenic synthesis of CoFe2O4@Ag nanocomposite for photocatalysis of organic pollutants (Rhodamine-B).
[008] Another object of the embodiments herein the antibacterial activity of the biogenic synthesis of CoFe2O4@Ag was demonstrated using the well diffusion assay.
[009] Still another object of the embodiments herein the on the human breast cancer cell MCF-7, the in vitro cytotoxicity effects of biogenic synthesized CoFe2O4 and CoFe2O4@Ag were examined and the MCF-7 cells' 50% inhibitory concentration (IC50) was 60 µg/mL.
Summary of Invention:
[010] The current study used reducing and capping agents produced from the Carissa carandas plant to make CoFe2O4 and CoFe2O4@Ag nanocomposites. Through analyses using UV-Vis and FT-IR, the functional groups involved in the synthesis of nanocomposites were discovered. The active elements present in the plant extract stabilized the metal oxide nanoparticles. The E.D.X. examination revealed the percentage of components contained in the samples and confirmed the creation of nanocomposites. Rhodamine-B degradation was used to test the applicability of the biosynthesized material, and it was discovered that CoFe2O4@Ag had a much better photocatalytic performance, almost ? 98 % , than CoFe2O4 within 35 minutes. CoFe2O4 and Ag nanoparticle interface lead to closely matched band energies, which enhances photocatalytic activity. When tested using a suitable diffusion technique, the green synthesised nanocomposites showed good antibacterial efficacy against the chosen harmful microorganisms. Additionally, the cytotoxicity of CoFe2O4 and CoFe2O4@Ag hybrid nanocomposites was evaluated using MCF-7 cancer cells, and it was discovered that cell viability varied against the nanocomposites. This work may provide fresh perspectives on how to make highly activated, effective photocatalysts under UV light. Additionally, it provides a workable way to maximise the solar efficiency of CoFe2O4@Ag hybrid photocatalysts. The findings might give a chance to create hybrid nanocomposites and increase their capacity to filter out hazardous dyes, germs, and cytotoxicity.
Brief description of drawings:
[011] Figure 1. Schematic diagram of biosynthesis of CoFe2O4 and CoFe2O4@Ag nanocomposites.
[012] Figure 2. (A) UV-visible spectra (B) FT-IR spectra of the of (a) plant extract (b) CoFe2O4 (c) CoFe2O4@Ag
[013] Figure 3. Scanning electron microscopic images of (A-B) CoFe2O4 and (C-D) CoFe2O4@Ag nanocomposites (E) Energy dispersive x-ray spectra of CoFe2O4@Ag nanocomposites and dot mapping pattern of CoFe2O4@Ag nanocomposites (F) XRD patterns of CoFe2O4 and CoFe2O4@Ag nanocomposites (G) B.E.T. analysis of nitrogen adsorption-desorption isotherm.
[014] Figure 4. (A) Effect of pH on the degradation of RhB (B-C) Time-dependent change of absorption spectra of RhB solution with the CoFe2O4 and CoFe2O4@Ag nanocomposite under UV light irradiation (D) Photocatalytic degradation of RhB under biosynthesis nanocomposites of CoFe2O4 and CoFe2O4@Ag (E) Kinetic results of RhB degradation under biosynthesis nanocomposites of CoFe2O4 and CoFe2O4@Ag.
[015] Figure 5. (A) Radical scavenger tests over CoFe2O4@Ag nanocomposite for RhB degradation and (B) P.L. spectra change as a function of irradiation time over CoFe2O4@Ag nanocomposite for TAOH (C) Proposed mechanism for the degradation of rhodamine-B dye using the synthesized nanocomposites
[016] Figure 6. (A) The recycle test of CoFe2O4@Ag hybrid nanocomposites for RhB photodegradation under light irradiation (B) XRD for the used CoFe2O4@Ag hybrid nanocomposites after five cycles.
[017] Figure 7. (A-D) Antimicrobial activity of the green synthesized and CoFe2O4@Ag for studied bacteria (E) Comparison of inhibition zones in mille meters for studied bacteria over CoFe2O4 and CoFe2O4@Ag (F) M.T.T. assay results for the anticancer activity of biosynthesised CoFe2O4 and CoFe2O4@Ag.
Detail description of invention:
[018] CoFe2O4 and CoFe2O4@Ag nanocomposites were made based on an extract of the Carissa carandas plant, and they were examined by FTIR, UV-vis, XRD, and FE-SEM, E.D.X. and B.E.T. The many excitation peaks produced by light at specific wavelengths to form surface plasmonic resonances can be found using UV-visible spectroscopy. The surface plasmon resonance peak's appearance and placement are typically determined by the nanoparticle's size and form [28]. Carissa carandas plant extract and a nanocomposite of CoFe2O4 and CoFe2O4@Ag dispersed in an aqueous solution are shown in Fig. 2A's UV-visible spectroscopy data. Due to the biomolecules (alkaloids, terpenoids, and other organic chemicals) present, the plant extract exhibits strong absorption bands between 220 and 350 nm, as seen in Fig. 2A (peak a). Figure 2A (peak b) shows that biosynthesized nanocomposites lack significant absorbance bands between 220 and 350 nm. An Ag peak-corresponding surface plasmon resonance peak appeared at 368 nm, as illustrated in Fig. 2A (peak c). This demonstrated the cortical extract's effectiveness from Carissa carandas's bark in producing CoFe2O4 and CoFe2O4@Ag. In addition, the dark, almost black colour of the CoFe2O4@Ag showed stability for up to a month. Several other studies have published results for the distinctive peak of green synthesised CoFe2O4@Ag that are similar to the current study [28].
[019] The band gap energy is essential for effectively predicting semiconductors' photophysical and photochemical characteristics. The equation suggested by Tauc, Davis, and Mott and UV-visible absorption spectroscopy was used to determine the semiconductor band structure of CoFe2O4@Ag [29].
(ah?)n = k(h? - Eg)
Where the band gap, the absorption constant, the absorption energy, and the absorption coefficient are, in order, a, h?, k, and Eg. The index n equals 2 for a direct transition and 0.5 for an indirect transition. Thus, for the CoFe2O4 and CoFe2O4@Ag nanostructures, according to a plot of the (ah?) 0.5 vs. h, the predicted band gaps are roughly 2.92 eV and 2.53 eV, indicating the substantial potential for the broad range of UV-vis as well as solar spectrum.
[020] FTIR spectroscopy was used to examine Carissa carandas plant extract, CoFe2O4 and a hybrid CoFe2O4@Ag nanocomposite as shown in Fig. 2B. FTIR spectrum of Carissa carandas extract sample (Fig. 3a), the absorption peaks at 1119.09, 1384.11, 1644.20, 2085.03, 2928.34, 3394.67 cm-1 corresponded to the C-O streching, C-H bending, C=C stretching, C=C=N stretching, -C.H. stretching and -O.H. stretching groups. In Fig. 3b, the CoFe2O4 nanocomposites has absorption peaks at 539.14 (C=O stretching), 1029.23 (C=C stretching), 2928.42 (-C.H. stretching), 3418.66 cm-1 (-O.H. bonds), which can be ascribed to the involvement of biomolecules of plant extract. The results further proved that CoFe2O4@Ag can be reduced and form a hybrid structure. The C=C group peaked at 1619.26 cm-1, the C-N group at 1317.08 cm-1, and the C-O group at 1019.16 cm-1 in the spectrum of CoFe2O4@Ag, but at lower wavenumbers as shown in Fig. 3c. Additionally, the O-H functional group including phytoconstituents played an active part in the reduction and stabilization of CoFe2O4@Ag as evidenced by the disappearance of the Carissa carandas' strong O-H group. The current findings are compatible with prior research on CoFe2O4 nanocomposites that have been published, as previously stated [28]. The data obtained suggest that the medium's dielectric constant may have changed due to the participation of numerous distinct phytochemicals from the extract of Carissa carandas. As previously explained [30], capping agents such as alkaloids, flavonoids, glycosides, and phenolic acids are thought to alter or diverge from the peak positions of the CoFe2O4@Ag spectrum. According to FT-IR studies, bioorganic chemicals from plant extracts can significantly affect the materialization of nanocomposites. The FE-SEM technique was used to investigate the morphologies of biosynthesized CoFe2O4 and CoFe2O4@Ag nanocomposites as shown in Fig. 3. The S.E.M. images of CoFe2O4 and CoFe2O4@Ag nanocomposites made from plant extract are shown in Fig. 3A–B and Fig. 3C–D at various magnifications and demonstrating porous complex shape agglomerates with nano grained structures. Additionally, the uniform distribution of nano-sized particles of CoFe2O4 and CoFe2O4@Ag was achieved by minimizing the aggregation, accomplished by using plant extracts as both capping agents and reducing agents. There was no discernible difference in the size of the nanoparticles, and almost all of them were poly-disperse spherical shapes with even distribution over the surfaces when they were prepared at the optimal calcination temperature. The biosynthesized nanocomposites' spherical forms improve their antibacterial, anticancer, and catalytic characteristics, and the average particle sizes produced (? 34.87 nm) are clearly in the nanostructure range[31]. Using E.D.X. analysis, the elemental composition of CoFe2O4 and CoFe2O4@Ag nanoparticles was determined. The E.D.X. data displays the amounts of oxygen, iron, cobalt, and silver in the structural design. Thus, the data is in favour of the synthesis of pure CoFe2O4 and CoFe2O4@Ag nanocomposites. The distribution of the elements O, Fe, Co, and Ag within the pertinent structural composition can be seen by elemental mapping. The samples are shown in Fig. 3E of E.D.X. analysis proved that pure CoFe2O4 and CoFe2O4@Ag nanocomposites were produced.
[021] The purity and structural composition of the biosynthesized (CoFe2O4 and CoFe2O4@Ag) nanocomposites were examined using the XRD method. Fig. 3F depicts the XRD pattern of CoFe2O4 and CoFe2O4@Ag nanocomposites. The 220, 311, 222, 400, 331, 422, 511, 440, 531, 620, 533, 622, and 444 crystal planes of the spinel CoFe2O4 are well congruent with the XRD diffraction peaks at 30.14°, 35.50°, 37.12°, 43.11°, 47.15°, 53.52°, 57.00°, 62.61°, 65.75°, 71.09°, 74.01°, 75.01°, and 79.02°. JCPDS card No. 22-1086[32] shows that plant extract was successfully employed to synthesise nanoscale materials because all of the observed diffraction peaks could be matched to the standard CoFe2O4@Ag hexagonal structure. However, CoFe2O4 showed additional Ag-related peaks due to Ag nanoparticles on its surface. These new signals were connected to the metallic Ag crystallographic planes (111), (200), (220), and (311) of the F.C.C. structure [29]. No contaminant peaks can be seen in the diffraction patterns of the hybrid CoFe2O4@Ag nanocomposites, which show peaks for both CoFe2O4 and Ag.
[022] The XRD measurements supported the two-phase CoFe2O4 and Ag composition of these hybrids. According to the Debye-Scherrer equation (D= k?/ßcos?), which is in good agreement with FESEM data, the crystallite size was estimated to be around ?35 nm. Fig. 3G displays the N2 adsorption-desorption curves for CoFe2O4 and CoFe2O4@Ag samples and their computed specific surface areas (SBET). The samples' mesoporosity was demonstrated by the IV-type curves in all isotherms and were based on the BDDT classification [33]. For samples of CoFe2O4 and CoFe2O4@Ag, the estimated values of SBET were 135.9 and 163.7 m2g-1, respectively. CoFe2O4@Ag nanocomposite sample has a significantly higher SBET value than CoFe2O4 sample, indicating that the addition of Ag NPs lowers the agglomeration of cobalt ferrite nanoparticles and causes the SBET increase. As a result, the addition of Ag NPs may cause a rise in the specific surface values, which may have an impact on both optical and photocatalytic activities.
[023] The pH of the solution frequently influences the photodegradation of organic contaminants. The pH of the reaction solution was changed from 3 to 12 using H2SO4 or NaOH in order to evaluate the influence of solution pH on the photocatalytic degradation of RhB over CoFe2O4@Ag nanocomposite. The point of zero charges (pHpzc) of CoFe2O4 and CoFe2O4@Ag was discussed by Jayalakshmi and coworkers[34], and the values were found to be 9.3 and 9.0, respectively, suggesting that the charge on the surface of the materials being produced will be neutral at this point. At a pH lower than their pHpzc, which is the optimal pH for the sequestration of negatively charged impurities, the outermost layer of CoFe2O4@Ag will become positively charged. It’s surface will be negatively charged at a pH greater than the pollutants' pHpzc values, which is the optimal pH for removing positively charged contaminants. The RhB decomposition rate increased from 30.1% to 97% while the pH of the solution increased from 3.0 to 9.0 after 35 min of irradiation; however, as the pH rose further to 10 and 12, the rate of degradation gradually decreased to 88.2% and 70.1%, respectively, as shown in Fig. 4A. Since the aromatic carboxylic acid group on RhB has a pKa of less than 4.2, it is well known that RhB is fully protonated at pH values lower than 4.2. The least amount of photodegradation was possible at this pH because electrostatic repulsions made it less likely for positively charged (cationic) RhB molecules to interact with the positively charged surface of the CoFe2O4@Ag. The COOH groups on RhB become deprotonated around pH 5.0, which causes RhB to change from a cationic to a zwitterionic form [32]. As a result, the RhB and positively charged catalyst exhibits an electrostatic affinity, somewhat increasing the photodegradation capabilities at this pH. RhB changes from its zwitterionic to anionic state as the pH rises from 5 to 7, and at pH 9.0 it exhibits the most attraction to the positively charged CoFe2O4@Ag and negatively charged RhB. Since CoFe2O4@Ag and RhB both have negative charges and cause more repulsions, raising the pH will reduce the capacity for photodegradation. As a result, it was shown that RhB photodegrades most quickly at pH 9.0, followed by pH 9 (alkali pH) > pH 7 > pH 11 > pH 3.
[024] The photocatalytic degradations of RhB solution in the presence of CoFe2O4 and hybrid CoFe2O4@Ag nanocomposites are shown in Figs. 4B-C. The colour of RhB dye aqueous solutions rapidly waned during photodegradation. The CoFe2O4@Ag hybrid showed increased photocatalytic performance when exposed to UV light compared to pure CoFe2O4. The CoFe2O4@Ag hybrid also virtually entirely photodegraded the RhB dye pollutant after being exposed to UV light for 35 minutes. The CoFe2O4@Ag (97.42%) hybrid composite showed a greater ability to degrade RhB in the UV area than the pure CoFe2O4 (77.83%) due to the good surface plasmon resonance effect. The photocatalytic activity under U.V. light with 10 mg of CoFe2O4 and CoFe2O4@Ag catalysts improved due to the hybrid's synergistic effects and surface absorption characteristics. In a control experiment, CoFe2O4 and CoFe2O4@Ag composites were not added, and RhB photolysis was conducted in the presence of a light source. The data obtained showed that the rate of RhB degradation did not alter significantly (only by 6%) after being exposed to light for about 35 minutes, demonstrating that the degradation process is totally dependent on the interaction between light and catalysts.
[025] The kinetic models can be used to understand the mechanism of degradation, chemical reaction, mass transfer and diffusion control followed by pseudo-first (linear models) or pseudo-second (absorption models) order kinetics. A pseudo-first-order model was used to adjust the reaction kinetics of the RhB photodegradation by nanocomposite, and the degradation data were expressed as ln(C_0/C_t )=-kt, where k = pseudo-first-order rate constant (min-1), t = irradiation time, C = concentration at time t of the RhB aqueous solution (µg/mL), and C0 = initial RhB concentration (µg/mL). The k value is determined by linear fitting with the samples. The RhB solution's photocatalytic decomposition kinetics is shown in Fig. 4D-E, with varied time delays when UV light is present. CoFe2O4 exhibits a relatively low k value by UV light exposure (k=1.059 min-1), whereas CoFe2O4@Ag has the highest photocatalytic activity (k=1.448 min-1) (Fig. 4E). The results thus showed that the addition of Ag nanoparticles could increase CoFe2O4's photocatalytic activity.
[026] The oxidation-reduction reactions caused by the reactive radicals generated during the photoreaction were crucial in the photodegradation of organic contaminants. By selectively quenching the h+, .O2, H2O2, and . O.H. radicals with EDTA, B.Q., catalase, and I.P.A. in this process system, the primary species that is active in the photodegradation action and the transferring pathway of the photogenerated carriers of charge were identified. It was well recognised that the more a quencher reduced photoactivity, the more the corresponding active species contributed to the destruction of contaminants. The data showed that B.Q. had little to no influence on RhB, indicating that .O2- radicals only had a modest role. Additionally, the photocatalytic activities were only marginally decreased by the addition of EDTA and catalase, showing that the role of h+ and H2O2 in the degradation process was minimal. Catalase and EDTA were also added, which somewhat hindered the photocatalytic activities and showed minimal amount of h+ and H2O2 that contributed to the degradation process. However, the addition of I.P.A. significantly reduced RhB degradation. As a result, as seen in Fig. 5A, . O.H. radicals served as the primary catalyst for mediating the photocatalytic activities. In an effort to further rule out the occurrence of . O.H. radicals in photocatalysis, acetonitrile was used as the reaction media. It was discovered that the nonaqueous photocatalytic system reduced the degradation of RhB almost totally. This provided more evidence that the major species involved in the current photocatalytic system was the . O.H. radical. It has also been demonstrated that TAOH, a straightforward chemical reaction that may occur when . O.H. radicals contact with T.A., emits a strong fluorescence signal at about 425 nm. No P.L. signal was seen in the absence of light irradiation, as shown in Fig. 5B. However, it was discovered that the observed P.L. intensity increased gradually with longer exposure times, corroborating the notion that . O.H. radicals were produced and actively participated in the photodegradation event [27].
[027] The following method was suggested for the photocatalytic degradation of RhB on CoFe2O4 and CoFe2O4@Ag nanostructures. The CoFe2O4 photocatalyst produces electron-hole pairs when a photon with the right energy (2.92 eV) strikes its surface, which excites electrons to move from the valance band to the conduction band. While the electrons (ecb¯) have a sizable reducing capacity, the holes (hvb+) have a high oxidising capacity. When these electrons reduce the electron acceptors, such as dissolved oxygen or water, superoxide radical anions (?O2¯) are created[35]. On the other hand, photogenerated holes oxidise ¯OH or H2O molecules to hydroxyl radicals (?OH). As a result, CoFe2O4's surface molecules that have been adsorbed react with the resulting electrons, holes, ?O2¯, and ?OH radicals. Practically all RhB molecules can be oxidised by ?OH, a potent oxidant with a high standard redox potential of +2.8 V, to produce counterproductive end products. RhB gradually degrades into CO2, H2O, and HCl when interacting with ?OH radicals. As already mentioned, the addition of Ag NPs enhances the UV-visible light sensitivity of CoFe2O4 and speeds up the generation of photogenerated electron/hole pairs by minimising the recombination effect. Because of the greater conductivity that Ag NPs offered along the molecule, a set of energy levels that they conferred enhanced the vectorial charge transmission by having a band gap of 2.53 eV. The list of chemical reactions that made up the photocatalysis mechanism is shown in Fig. 5C. CoFe2O4 plays a critical role in the photodegradation of RhB as an absorber and supporter for the charge carrier transition for the CoFe2O4@Ag system through a synergistic influence and effective interface between the CoFe2O4 and Ag nanoparticles. Comparing the biosynthesized CoFe2O4@Ag photocatalytic performance to some of the previously reported materials, it was found that the newly synthesised material has its advantages in terms of effectiveness, degradation time, and catalyst quantity, as shown in Table 1.
CoFe2O4 + h? ? CoFe2O4* + ecb- + hvb+
CoFe2O4@Ag + h? ? CoFe2O4@Ag* + ecb- + hvb+
ecb- + O2 ? •O2¯
hvb+ + H2O ? H+ + ?OH
hvb+ + -OH ? ?OH
?OH + RhB ? degradation products
•O2¯ + RhB ? degradation products
According to theory, there are two major ways that RhB can be broken down: either directly by photogenerated holes, or through a reaction with superoxide or hydroxyl radicals produced by photocatalysts. It is essential to identify the active species involved to determine the reaction process in photocatalytic reactions. The RhB solution's temporal UV-spectral alterations while being exposed to radiation are shown in Fig. 5C. The greatest absorption peak of the RhB at 553 nm changed somewhat as the irradiation duration lengthened, demonstrating that the hypsochromic shifts of the absorption band were quite minor. The N-deethylation of RhB caused hypsochromic alterations in the RhB absorption in numerous photocatalytic reactions, according to earlier study[36, 37]. The progressive deethylation that produced N-ethylrhodamine (E.R., ?max: 510 nm), N, N-diethylrhodamine (D.R., ?max: 522 nm), N, N-diethyl-N-ethylrhodamine (D.E.R., ?max: 539 nm), and RhB at 498 nm is what causes the hypsochromic shift in the maximum wavelength of RhB. Meanwhile, it took some time for our testing to reveal the hypsochromic shifts of the absorption band.
[028] However, when the irradiation time was prolonged to 20 min, the normal RhB absorption band began to show a slight blue shift, and when the irradiation time was increased to 35 minutes, the spectral blue shift was from 553 to 540 nm. RhB degradation was found to be primarily caused by the fragmentation of the whole chromophore architecture as a result of minor deethylation. Additionally, the band at 210 nm might be brought on by the long-term degradation of carboxylic acids. The outcomes were similar to Balangetti's [38] findings regarding the photodegradation of paracetamol.
[029] The efficiency and utility of any photocatalyst depend on its capacity for replenishment and recycling [39]. Regeneration studies on CoFe2O4@Ag were therefore carried out. Five cycles of photocatalytic experiments were run using 100 mg of CoFe2O4@Ag loaded with 50.0 mL of RhB aqueous solution containing 50 ppm. Between the first and fifth cycles of use, the photocatalytic degradation efficiency was observed to fall from 97.4 to 86% (Fig. 6A). The roughly full breakdown of RhB in each cycle was accompanied by no noticeable alterations, illuminating the practical application of CoFe2O4@Ag for environmental cleanup. The efficiency loss for RhB photodegradation was only about 11% after five recycling processes. Sample loss after each cycle, which is unavoidable, could be the cause of the modest decline in deteriorating efficiency. The structural alterations of the applied CoFe2O4@Ag nanocomposite were further examined by XRD analysis, as shown in Fig. 6B [27]. According to the data, the photocatalytic activity towards RhB degradation with exceptional stability and sustainability points to the possibility that this material could serve as a reliable photocatalyst.
[030] The recent development of antibiotic resistance in certain pathogenic microorganisms has adversely impacted human health. Due to their ability to fight pathogens, nanomaterials have recently attracted attention [40]. In this study, the well diffusion technique was used to evaluate the antibacterial effectiveness of the biogenically synthesised CoFe2O4 and CoFe2O4@Ag nanocomposite against human bacterial pathogens like B. subtilis, S. aureus, P. aeruginosa, and E. coli, as shown in Fig. 7A-D. With inhibition zones of 18.5 ± 0.75, 12.2 ± 0.57, 15.7 ± 1.6 and 14.8 ± 0.5 mm and 24.3 ± 0.75, 17.4 ± 0.57, 20.5 ± 1.6 and 19.8 ± 0.5 mm respectively, the maximum CoFe2O4 and CoFe2O4@Ag dose (10 mg) demonstrated a high level of inhibitory activities against the pathogens B. subtilis, S. aureus, P. aeruginosa and E. coli (the bar diagram of comparison between two materials can be seen in Fig. 7E). Previous studies demonstrated that silver particles effectively combat pathogenic bacteria, both Gram-positive and Gram-negative [40]. Ag-modified CoFe2O4 nanocomposites have an antibacterial effect on bacteria through the degradation of cell walls, disruption of structural proteins, inactivation of enzymes, inhibition of electron transport chains, oxidative stress caused by the generation of reactive oxygen species, and damage to nucleic acids. Electrostatic contact is believed to be the most crucial element in the interactions between bacterial cells and nanocomposites. In general, permeabilization of the cell surface causes intracellular substances to leak out, which ultimately causes the death of bacterial cells. CoFe2O4@Ag is now a good antibacterial treatment option and has applications in medicine.
[031] Using the human breast cancer MCF-7 cell lines, the in vitro cytotoxicity of the greenly synthesised CoFe2O4 and CoFe2O4@Ag nanocomposites was examined. By using the M.T.T. assay, MCF-7 cell lines were treated with various doses of CoFe2O4 and CoFe2O4@Ag (10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 g/mL) nanocomposites for 48 h and equated with DMEM which is used as control [41]. The M.T.T. reagent reduction and tetrazolium dyes changes the yellow colour based on cellular metabolic activities due to N.A.D. (P)H-dependent cellular oxidoreductase enzymes. After exposure to CoFe2O4 and CoFe2O4@Ag, cell viability was dramatically reduced, and the IC50 was discovered to be 60 g/mL. High-density dead cells were seen after MCF-7 cells were treated with biosynthesized CoFe2O4 and CoFe2O4@Ag; these morphological alterations demonstrated the improved cytotoxic effect [42]. The smaller particle size and larger surface area to volume ratio may cause the more significant cytotoxic effect. Additionally, it is essential to note that the ethanolic leaf extract contains phytoconstituents from the carissa carandas plant, which have been shown to have specific anticancer activities, mostly through targeting cancer-related proteins [20].
[032] Phase I metabolism, D.N.A. damage pathways, phase II metabolism, stimulation of carcinogen-detoxifying enzyme, overcoming chemoresistance, paraptosis, modulation of oxidative stress, autophagy, induction of apoptosis, radiosensitization, or striking the cancer cell cycle are some of the potential cyctotoxic mechanisms[43]. Finding its potential anticancer action mechanism is another focus of research. Since the p values are < 0.0001 in Fig. 7F, the mean changes are statistically significant and the data are presented as mean S.D. (n = 3). This study is consistent with the literature evidence, which indicates that nanoparticle toxicity varies with concentration, especially at lower levels[44].
, Claims:1. A method for facile Biogenic synthesis of CoFe2O4 and CoFe2O4@Ag nanocomposites from Carissa Carandas plant bark cortex and effective on photocatalytic, antibacterial and cytotoxic study and containing the following steps:
• Fresh Carissa carandas plant stems were obtained on the campus of the S.V. Agricultural University in the Tirupati district of Andhra Pradesh. Peeling off, slicing into small pieces, and thoroughly washing with both tap and ultrapure water. The well cleaned bark cortex was warmed at 70 oC for three hours while being agitated in hot water at 250 oC on a regular basis. To obtain a superior extract, the extract was allowed to rest overnight before being filtered using Whatman No. 1 filter paper. To make CoFe2O4 and CoFe2O4@Ag nanocomposites, the extract was maintained at a low temperature and in darkness (4 oC) in a refrigerator.
• CoFe2O4 and CoFe2O4@Ag nanocomposites were created here utilising a plant extract from Carissa carandas. The 1:2:0.5 ratio of cobalt nitrate, iron nitrate, and silver nitrate was dissolved in an aqueous solution and combined with stirring in a 100 mL beaker. The metal solution was heated to 80 oC for an additional 45 min after the Carissa carandas plant extract was added. After that, the mixture was dropped-wise added to 0.05 M NaOH to achieve an alkaline pH of ? 10. After 3 h of stirring in the solution, CoFe2O4@Ag precipitated after centrifugation at 8000 rpm. The obtained nanoparticles were then washed with ethanol and distilled water and dried at 80 oC for 3 h. It was heated to 500 oC for two hours as part of the annealing procedure. The aforementioned process was replicated to create CoFe2O4 nanocomposites without using silver. Fig. 1 illustrates the development of nanocomposites schematically.
• Using a UV lamp (315-400 nm) with a 40-watt output, the photocatalytic activity of biosynthesized CoFe2O4 and CoFe2O4@Ag nanocomposite against RhB was examined. For this, a 50 mL aqueous RhB (30 ppm) solution in a 100 mL beaker is added to 10 mg of biosynthesized CoFe2O4 and CoFe2O4@Ag nanocomposite. The photocatalyst and pigment solution was then stirred in the dark for 30 min in order to ensure adsorption-desorption stability before being exposed to UV light. The dye solution was then exposed to UV light and 2 ml portions were taken out at regular intervals. The remaining concentration of RhB in an aqueous solution was then determined by measuring the dye concentration using a UV-visible spectrophotometer at a wavelength of 554 nm.
• The CoFe2O4 and CoFe2O4@Ag nanocomposites were tested for their capacity to prevent bacterial growth using the well-diffusion method. S. aureus, E. coli, B. subtilis, and P. aeruginosa were the four bacteria employed in the testing. In a sterile Petri plate with 20 mL of Mueller-Hinton solution, test bacteria (1×108 CFU/mL) were inoculated by streaking method. The wells were made with a sterile cork borer of 6 mm, and 200 L of CoFe2O4 and CoFe2O4@Ag nanocomposites were introduced with a concentration of 10 mg each. Inoculated plates were chilled for 45 min before being incubated at 37 °C for 24 h in order to achieve sufficient CoFe2O4 and CoFe2O4@Ag diffusion for the bacterial test. Each well's inhibitory zone's circumference (in mm) was measured.
• The CoFe2O4 and CoFe2O4@Ag nanocomposites were tested for their capacity to prevent bacterial growth using the well-diffusion method. S. aureus, E. coli, B. subtilis, and P. aeruginosa were the four bacteria employed in the testing. In a sterile Petri plate with 20 mL of Mueller-Hinton solution, test bacteria (1×108 CFU/mL) were inoculated by streaking method. The wells were made with a sterile cork borer of 6 mm, and 200 L of CoFe2O4 and CoFe2O4@Ag nanocomposites were introduced with a concentration of 10 mg each. Inoculated plates were chilled for 45 min before being incubated at 37 °C for 24 h in order to achieve sufficient CoFe2O4 and CoFe2O4@Ag diffusion for the bacterial test. Each well's inhibitory zone's circumference (in mm) was measured.
2. The method as claimed in claim 1, wherein the biogenic synthesis of CoFe2O4@Ag is used as a photocatalysis of organic pollutants (Rhodamine-B)
3. The method as claimed in claim 1, wherein the biogenic synthesis of CoFe2O4@Ag provided the photocatalytic activity at UV-light in natural pH.
4. The method as claimed in claim 1, wherein the biogenic synthesis of CoFe2O4@Ag nanocomposite showed excellent antibacterial activity against gram positive and gram negative bacterial.
5. The method as claimed in claim 1, wherein the biogenic synthesis of CoFe2O4@Ag nanocomposite showed cytotoxicity.