Nayan Ranjan Saha

Studies on methylcellulose/pectin/montmorillonite nanocomposite films and their application possibilities.

Films based on methylcellulose (MC) and pectin (PEC) of different ratios were prepared. MC/PEC (90:10) (MP10) gave the best results in terms of mechanical properties. Sodium montmorillonite (MMT) (1, 3 and 5 wt%) was incorporated in the MP10 matrix. The resulting films were characterized by X-ray diffraction and transmission electron microscopy, and it was found that nanocomposites were intercalated in nature. Mechanical studies established that addition of 3 wt% MMT gave best results in terms of mechanical properties. However, thermo-gravimetric and dynamic mechanical analysis proved that decomposition and glass transition temperature increased with increasing MMT concentration from 1 to 5 wt%. It was also observed that moisture absorption and water vapor permeability studies gave best result in the case of 3 wt% MMT. Optical clarity of the nanocomposite films was not much affected with loading of MMT. In vitro drug release studies showed that MC/PEC/MMT based films can be used for controlled transdermal drug delivery applications.

In situ synthesis of a reduced graphene oxide/cuprous oxide nanocomposite: a reusable catalyst

A reduced graphene oxide/cuprous oxide (RGO/Cu2O) nanocomposite has been successfully synthesized applying a simple in situ reduction method using an aqueous solution of lactulose which is used simultaneously as a reducing and stabilizing agent. Lactulose, a disaccharide, has the ability to reduce both GO and CuSO4 in situ under alkaline conditions. The GO and RGO/Cu2O nanocomposites are characterized using transmission electron microscopy, energy dispersive X-ray spectroscopy, field emission scanning electron spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy and UV-vis absorption spectroscopy. The surface charge as well as stability is established by analyzing the zeta potential value. The results confirm the synthesis of the RGO/Cu2O nanocomposite and the existence of interactions between Cu2O and RGO. It is also observed that Cu2O nanoparticles with an average size of 5 nm are uniformly dispersed throughout the RGO sheets. The catalytic activity of the RGO/Cu2O nanocomposite is excellent for the ‘click’ reaction and remains the same for six cycles.

Physical and electrochemical characterization of reduced graphene oxide/silver nanocomposites synthesized by adopting a green approach

This study demonstrates the physical and electrochemical characterization of nanocomposites based on reduced graphene oxide (RGO) and silver nanoparticles (Ag NPs) synthesized by adopting a green and low cost approach using lactulose as a reducing and stabilizing agent. The RGO/Ag nanocomposites were characterized by X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, UV-vis absorption spectroscopy and transmission electron microscopy (TEM) to obtain clear information about the removal of functional groups and morphology of nanocomposites. XRD results confirmed the formation of a high purity crystal of Ag on RGO. FTIR results established partial reduction of GO to RGO by lactulose. TEM images show that spherical Ag NPs of an average size of 4 nm are uniformly deposited onto RGO sheets and also prevent the restacking of RGO layers. The energy dispersive X-ray spectra (EDX) of RGO/Ag nanocomposites indicate the presence of Ag and graphene. Also, EDX spectra of FESEM show that Ag content increases with the increasing concentration of AgNO3 in RGO/Ag nanocomposites. The surface charge as well as stability of the nanocomposites is examined by measuring the zeta potential while electro-conductivity is measured by potentiostat–galvanostat. The zeta potential and conductivity of RGO/Ag nanocomposites is greatly improved compared to GO and RGO. The electro-conductivity of RGO/Ag nanocomposites indicates that conductivity of RGO/Ag nanocomposite increases with increasing concentration of Ag. The electrochemical result also indicates the presence of a higher amount of ionic functional groups in GO than those in RGO and RGO/Ag nanocomposites. GO indicates the lowest current which gradually increased for RGO and RGO/Ag nanocomposites, respectively.

Taro corms mucilage/HPMC based transdermal patch: an efficient device for delivery of diltiazem hydrochloride.

The aim of this work is to examine the effectiveness of mucilage/hydroxypropylmethylcellulose (HPMC) based transdermal patch (matrix type) as a drug delivery device. We have successfully extracted mucilage from Colocasia esculenta (Taro) corms and prepared diltiazem hydrochloride incorporated mucilage/HPMC based transdermal patches using various wt% of mucilage by the solvent evaporation technique. Characterization of both mucilage and transdermal patches has been done by several techniques such as Molischs test, organoleptic evaluation of mucilage, mechanical, morphological and thermal analysis of transdermal patches. Skin irritation test is studied on hairless Albino rat skin showing that transdermal patches are apparently free of potentially hazardous skin irritation. Fourier transform infrared analysis shows that there is no interaction between drug, mucilage and HPMC while scanning electron microscopy shows the surface morphology of transdermal patches. In vitro drug release time of mucilage-HPMC based transdermal patches is prolonged with increasing mucilage concentration in the formulation.

Synthesis and characterization of graphene from waste dry cell battery for electronic applications

This study demonstrates the electronic applications of graphene synthesized from the graphite electrode of waste dry cell zinc–carbon batteries. Graphite powder [G (R)] is successfully recovered from the graphite electrode of waste batteries by acid treatment and used as starting material for synthesis of graphene oxide (GO) following Hummers method. Finally, reduced graphene oxide (RGO) was obtained from the chemical reduction of GO by hydrazine hydrate. RGO thus obtained was characterized by X-ray diffraction, Raman spectroscopy, Fourier-transform infrared spectroscopy, UV-vis absorption spectroscopy, dynamic light scattering, energy dispersive X-ray spectra and transmission electron microscopy to get detailed information about the structure and morphology of the RGO. All the above characterization results confirmed the restoration of sp2 conjugation and removal of functional groups after the reduction of GO and also the sheet like morphology of RGO. The surface charge and stability of RGO in an aqueous medium are examined by measuring zeta potential. An electrochemical study demonstrated that, at different sweep rates, the current is the highest for RGO and lowest for GO and the current increases with an increasing sweep rate for all materials. The loop area of all the samples at the 100 mV s−1 sweep rate is the highest. The galvanostatic charging/discharging measurements have also been performed for both the GO and RGO samples at a current density of 1 mA g−1. Electro-conductivity measurement shows that RGO has higher conductivity than GO due to the restoration of the sp2 structure. The current voltage (I–V) characteristics show a non-linear behavior of GO and the ohmic nature of RGO.

Cross-linked methyl cellulose/graphene oxide rate controlling membranes for in vitro and ex vivo permeation studies of diltiazem hydrochloride

Permeability characteristics of the anti-hypertensive drug, diltiazem hydrochloride, from uncross-linked and cross-linked methylcellulose (MC)/graphene oxide (GO) rate controlling membranes (RCMs) were investigated. The MC/GO membranes were cross-linked with different concentrations of glutaraldehyde (GLA) to examine the effect of cross-linking on the permeability characteristics. The ATR-FTIR spectra, along with solubility resistance, swelling studies, the molar mass between cross-links, and moisture absorption of cross-linked RCMs over the uncross-linked RCM confirmed the cross-linking between MC and GO. The cross sectional view of cross-linked and uncross-linked RCMs, as observed by SEM, showed that the porous and fibrillose structure of the uncross-linked RCM was disrupted after cross-linking. The cross-linked RCMs showed improved mechanical and thermal properties compared to the uncross-linked RCMs. In vitro and ex vivo drug release was found to depend on the concentration of the cross-linker, which suggests that drug delivery is controlled by the cross-link density of RCM.

Effect of carrageenan and potassium chloride on an in situ gelling ophthalmic drug delivery system based on methylcellulose

Our research is devoted to developing a methylcellulose (MC) based in situ gelling ophthalmic formulation using pilocarpine hydrochloride as a model drug, containing different proportions of i (iota)-carrageenan and potassium chloride. This study will evaluate the utility of the proposed formulation to be a substitute for traditional eye drops. Use of both i-carrageenan and potassium chloride of definite wt% effectively reduces the gel temperature of the virgin MC solution from 60 °C to 33.5 °C which is below physiological temperature. The conventional methods like test tube tilting, and viscosity measurements are used to determine the gelation temperature while the gels are subjected to swelling as well as a gel dissolution study. Subsequently, the outcome from in vitro and in vivo studies confirms that the present system may be a better alternative compared to conventional eye drops.

Cellulose nanofibrils/chitosan based transdermal drug delivery vehicle for controlled release of ketorolac tromethamine

Cellulose nanofibrils (CNFs) have attracted attention as a promising material in the biomedical field because of their outstanding properties such as hydrophilicity, biocompatibility, biodegradability, and high surface area. In this work, we have prepared cellulose nanofibrils from jute fibres (JF), to develop a CNF/chitosan transdermal film for the delivery of ketorolec tromethamine (KT) where the CNFs act as an elegant nanometric carrier. The KT-loaded CNF/chitosan transdermal film matrices have been characterized by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Fourier transform infrared spectroscopy (FTIR) reveals the successful KT loading into the CNF/chitosan transdermal film. Scanning electron microscopy (SEM) study shows the different morphological features of the CNF/chitosan transdermal films. The crystalline nature of the CNF/chitosan transdermal films has been analyzed by X-ray diffraction study. Release profiles from the CNF/chitosan matrices indicate that the drug release rate is sustained with the incorporation of CNFs. We believe that this new nanocarrier may be a potential choice for transdermal drug delivery systems.

Development of active packaging material based on cellulose acetate butyrate/polyethylene glycol/aryl ammonium cation modified clay

Active packaging is one of the interesting concepts in food industry which extend the shelf-life of the food products. The purpose of this work was to develop nontoxic antimicrobial nanocomposite films. Benzyltrimethylammonium chloride modified montmorillonite (BMMT) were used as nano-filler and the prepared BMMT was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis. Polyethylene glycol (PEG) plasticized cellulose acetate butyrate (CAB) films with different ratios of PEG and CAB was prepared and it was found that the 20 wt% PEG in CAB matrix (CBP20) gave optimal results in terms of mechanical properties. BMMT was mixed with CBP20 in different proportions to prepare nanocomposites. 3 wt% BMMT loaded nanocomposite gave best in terms of the barrier and mechanical properties. The storage modulus, thermal stability, glass transition, and melting temperature of the nanocomposites increased with the loading of 1, 3, and 5 wt% of BMMT. Furthermore, these nanocomposites showed nontoxic and antimicrobial behavior.

Development of an auto-phase separable and reusable graphene oxide-potato starch based cross-linked bio-composite adsorbent for removal of methylene blue dye

In this work, we report the development of a cross-linked bio-composite consisting of graphene oxide, potato starch, cross-linker glutaraldehyde and its application to adsorption of the industrial dye, methylene blue, from aqueous solution. The inexpensiveness, non-hazardous nature and easy bio-degradability are the major reasons for the selection of starch material as one of the components of the bio-composite. The bio-composite has been characterized by FTIR, SEM, XRD, particle size and zeta potential analysis. The FTIR analysis reveals the nature of the binding sites and surface morphology of the bio-composite can be understood through SEM. The auto-phase separability of the adsorbent i.e., the precipitation of the adsorbent without any mechanical means is another factor which makes this particular material very attractive as an adsorbent. Parameters like adsorbent dosage, pH, temperature, rotation speed and salt concentration have been varied to find out the suitable dye adsorption conditions. Furthermore, the time dependence of adsorption process has been analyzed using pseudo-first and pseudo-second order kinetics. The adsorption isotherms have been constructed to suggest convincing mechanistic pathway for this adsorption process. Finally, desorption studies have been successfully performed in 3 cycles, establishing the reusability of the material, which should allow the adsorbent to be economically promising for practical application in wastewater treatment.