Synthesis of chitosan succinate-g-amine functionalized mesoporous silica: Inorganic-organic nanohybrid for antibacterial assessment, antioxidant activity and pH-controlled drug delivery.

An innovative and proficient inorganic-organic nanohybrid was synthesized by using amine modified MCM-41 as an inorganic precursor combined with organic moiety, a derivative of chitosan i.e. chitosan succinate through amide bond. These nanohybrids can be used in diverse applications due to potential combination of desired properties of inorganic and organic components. The nanohybrid was characterized by FTIR, TGA, small angle powder XRD, zeta potential, particle size distribution, BET, proton NMR and 13C NMR techniques to confirm its formation. The synthesized hybrid was loaded with curcumin drug to check its potential application for controlled drug release, showing 80 % drug release in acidic medium (i.e. pH -5.0), while physiological pH -7.4 shows only 25 % release. The encapsulation efficiency of nanohybrid is 87.24 %. The results of antibacterial performances are demonstrated in terms of ZOI (zone of inhibition) which depicts that hybrid material shows better ZOI in gram negative (E. coli) than for gram positive (B. subtilis) bacteria. Nanohybrid was also tested for the antioxidant activity by using two different methods (DPPH and ABTS) radical scavenging methods. The ability of nano-hybrid to scavenge DPPH radicals was found 65 %, and ability to scavenge ABTS radicals was 62.47 %.

A photocatalyst-free visible-light-mediated solvent-switchable route to stilbenes/vinyl sulfones from ß-nitrostyrenes and arylazo sulfones.

Photocatalyst-free visible-light-mediated reactions, based on the presence of a visible-light-absorbing functional group in the starting material itself in order to exclude the often costly, hazardous, degradable and difficult to remove or recover photoredox catalysts, have been gaining momentum recently. We have employed this approach to develop a denitrative photocatalyst-free visible-light-mediated protocol for the arylation/sulfonylation of ß-nitrostyrenes employing arylazo sulfones (bench-stable photolabile compounds) in a switchable solvent-controlled manner. Arylazo sulfones served as the aryl and sulfonyl radical precursors under blue LED irradiation for the synthesis of trans-stilbenes and (E)-vinyl sulfones in CH3CN and dioxane/H2O 2 : 1, respectively. The absence of any metal, photocatalyst and additive; excellent selectivity (E-stereochemistry) and solvent-switchability; and the use of visible light and ambient temperature are the prime assets of the developed method. Moreover, we report the first photocatalyst-free visible light-driven route to synthesize stilbenes and vinyl sulfones from readily available ß-nitrostyrenes.

Chitosan based ZnO nanoparticles loaded gallic-acid films for active food packaging.

Chitosan (Ch) and zinc oxide nanoparticles loaded gallic-acid films, (Ch-ZnO@gal) have been prepared aiming for their exploitation as environmentally benign food packaging material. The chitosan films with varying quantities of zinc oxide nanoparticles loaded gallic-acid (ZnO@gal) content were synthesized in order to evaluate the effect of ZnO@gal on their optimum mechanical and biological potential. The characteristic results have shown that the incorporation of ZnO@gal into chitosan films remarkably enhanced the desired mechanical property of the chitosan films. Other noticeable physical properties such as oxygen and water vapor permeability (WVP), swelling, water solubility and UV-vis light transmittance have also been found to improve positively. SEM analysis of the films indicates a good material compatibility between chitosan and ZnO@gal matrices. Ch-ZnO@gal films possess significant antibacterial potential and strong antioxidant behavior compared to pristine chitosan. The overall results suggested that the prepared biocomposite chitosan films may be considered for active food packaging applications.

A systematic study on chitosan-liposome based systems for biomedical applications.

The advent of liposome technology with its unique features has led researchers to work relentlessly on the successful development of novel drug delivery vehicles based on liposomes. But still there are some limitations of using liposomes for biomedical applications because of their poor stability that is primarily the cause of rapid leakage of drugs incorporated within the said matrices. Therefore, a considerable interest has been paid on modification of surface of liposomes by combining it with several compounds of interest. Although chitosan-liposome based systems are not yet well-documented. Hence, in this review, we exclusively focused on the discussion about the preparation of various chitosan-liposome based systems and their suitable biomedical applications as well.

Green synthesis, characterization and biological evaluation of chitin glucan based zinc oxide nanoparticles and its curcumin conjugation.

A well-organized, simplistic, and green route of chitin-glucan based zinc oxide nanoparticles (ChGC@ZnONPs) was synthesized using reducing and capping agent both in one as chitin-glucan complex (ChGC). Herein we report the bio-synthesis of Cur-ChGC@ZnONPs by the conjugation of curcumin (Cur) with ChGC@ZnONPs for the improvement of antioxidant and antibacterial activity. The synthesized nanoparticles were characterized by the UV-Visible (UV-Vis), particle size analyser, scanning electron microscope (SEM) with Energy-dispersive X-ray spectroscopy (EDX), Transmission electron microscope (TEM), X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR). Structure analysis, shape and crystalline size of nanomaterials were confirmed by scanning electron microscopy (SEM) and Transmission Electron Microscopy (TEM). The particle size analyser showed the particle size of nanomaterials and stability. Crystalline nature of both ChGC@ZnONPs and Cur-ChGC@ZnONPs were confirmed by the XRD spectra and FT-IR spectrum was used to examine the functional groups of nanomaterials. The antioxidant potential of conjugated nanomaterials were estimated using a DPPH free radical scavenging assay and ABTS+⁎ assay. This analysis showed that after loading of Cur, antioxidant activity increases. The antibacterial assessment of conjugated nanomaterials were tested by different microorganisms and showed excellent antibacterial activity.

Preparation, physicochemical and biological evaluation of quercetin based chitosan-gelatin film for food packaging.

Ecofriendly chitosan-gelatin (Ch-ge) bio-composite films containing Quercetin-starch (Q) were synthesized using solution casting method. Physicochemical characteristics and mechanical properties of the resulting chitosan-gelatin containing Quercetin-starch films (Ch-ge-Q) were studied using UV, FTIR, XRD and SEM techniques. The films were also investigated for their swelling, water-vapor permeability (WVP), water solubility properties. The FTIR spectra confirmed the chemical interactions between the chitosan-gelatin and Q. Surface morphology of prepared film was analyzed by the SEM imaging while XRD spectra suggest the expanded crystallinity of the film with the addition of Q. The film also showed enhanced barrier property against UV rays. The reduction of water-vapor permeability and increase in tensile strength while a decrease in elongation at break has been observed in the Ch-ge-Q film compared to Ch-ge film. The antibacterial activity of Ch-ge-Q film against both gram positive (B. substilis) and gram negative (E. coli) bacteria suggested the Q loaded Ch-ge films as more feasible antibacterial candidate especially against the strain E. coli. The antioxidant activity of the Ch-ge-Q film was evaluated using the DPPH and ABTS as standards and corresponded to 81.45% of DPPH and 72.2% of ABTS scavenging activities. It was observed that the film containing Quercetin-starch presented superior antioxidant activity results in comparison to Ch-ge film promising its application in food packaging.

Methyl methacrylate modified chitosan: Synthesis, characterization and application in drug and gene delivery.

A methyl methacrylate (MMA) modified chitosan (CS) conjugate (CSMMA) has been synthesized by a green method via Michael addition reaction between CS and MMA in ethanol. The synthesized conjugate was characterized by FT-IR, 1H NMR, X-ray diffraction spectrometry and SEM analysis. The results confirmed that CS was covalently linked to MMA yielding a highly porous framework. The uses of CSMMA were analyzed as a potential gene and drug delivery agent. CSMMA proved to be a reasonably good gene delivery agent based on transfection efficiency studies in mammalian cancer cell lines (A549, HeLa and HepG2). For drug delivery studies, nanoparticles of the CSMMA biopolymer were prepared by ionic gelation method with sodium tripolyphosphate (TPP). The prepared nanoparticles were characterized in terms of FE-SEM, DLS and zeta potential. In vitro drug release study of curcumin loaded CSMMA nanoparticles showed its maximal entrapment efficiency up to 68% and the drug release was more rapid at a pH (5.0) lower than physiological pH.

Chitosan grafted graphene oxide aerogel: Synthesis, characterization and carbon dioxide capture study.

We have demonstrated a superficial, environmentally friendly and sustainable development of chitosan (CS) grafted graphene oxide aerogels for adsorption of CO2 gas. The CS is grafted into the carbonaceous materials like graphene oxide, multi-walled carbon nanotubes etc. to provide the large surface area, high porosity and a large number of amine group which facilitates the adsorption of CO2 gas. CS and carbonaceous materials undergo crosslinking by using cross-linker reagents, and freeze-drying technique to yield CS based aerogels with ordered porous structures. Crosslinking between CS and carbonaceous materials was confirmed by FT-IR. Physical properties of the CS-based aerogels were studied using SEM, TGA, XRD, BET isotherm analysis. The adsorption capacity of CO2 gas by CS grafted graphene oxide aerogels is around 0.257 mmol g-1 at 1 bar, that is significantly higher in comparison to the adsorption capacity of pure CS. We believe that this study helps to reduce the cost of adsorbents due to the large availability of marine waste (CS) and thus aims to reduce the anthropogenic CO2 gas at low cost, favourable temperature and pressure as compared to previously reported.

Synthesis of chitin-glucan-aldehyde-quercetin conjugate and evaluation of anticancer and antioxidant activities.

In the present study, we have synthesized chitin-glucan-aldehyde-quercetin (chi-glu-ald-que) conjugate via condensation reaction. Synthesis of chitin-glucan-aldehyde (chi-glu-ald) complex was facilitated by the oxidation of chitin-glucan (chi-glu) complex. Formation of conjugate was confirmed by Proton nuclear magnetic resonance spectroscopy (1H NMR) and Fourier-transform infrared spectroscopy (FT-IR). Morphological studies showed that after grafting of quercetin, several changes on surface were depicted and a more crystalline nature was observed. The chi-glu-ald-que conjugate displayed strong antioxidant activity. It showed 69% of 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical, DPPH* scavenging activity at 1 mg/mL and 72% of 2, 2-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical cation, ABTS*+ scavenging activity at 1 mg/mL concentration, which are much higher than that of chi-glu complex. The anticancer activity of chi-glu-ald-que conjugate was performed in Macrophage cancer cell lines (J774) and biocompatibility was performed in Peripheral blood mononuclear cells (PBMCs). The chi-glu-ald-que conjugate showed excellent cytotoxicity against J774 cell lines but no cytotoxicity towards PBMCs.

Curcumin loaded chitin-glucan quercetin conjugate: Synthesis, characterization, antioxidant, in vitro release study, and anticancer activity.

In this study, we have synthesized chitin-glucan quercetin conjugate (ChGCQ) by an easy and facile free radical grafting reaction. The structure of ChGCQ was confirmed by proton nuclear magnetic resonance (1H NMR) and Fourier transforms infrared spectroscopy (FT-IR). Curcumin was loaded into ChGCQ to study its anti-cancer efficiency. The biocompatibility of ChGCQ and curcumin loaded ChGCQ (Cu-ChGCQ) were analysed by different assays in Peripheral blood mononuclear cells (PBMCs) and cytotoxicity test was performed in a macrophage cancer cell line (J774). The result shows tremendous biocompatibility of ChGCQ and Cu-ChGCQ in peripheral blood mononuclear cells and excellent cytotoxity in macrophage cancer cell line (J774). Chitin-glucan complex (ChGC), ChGCQ and Cu-ChGCQ showed 51%, 66% and 74% of DPPH radical-scavenging activity at 1mg/ml respectively, which are much higher than that of ChGC and in ABTS*+ assay 58%, 71% and 83% show radical-scavenging activity at 1mg/ml. Antioxidant assay of Cu-ChGCQ conjugate expressed much higher antioxidant activity than ChGCQ and ChGC. In vitro drug release study of Cu-ChGCQ conjuagate showed faster drug release in acidic medium in comparison to PBS of physiological pH and anticancer activity in vitro assay showed more anticancer activity of Cu-ChGCQ in comparison to ChGCQ conjugate.

Cu(II)-carboxymethyl chitosan-silane schiff base complex grafted on nano silica: Structural evolution, antibacterial performance and dye degradation ability.

O-Carboxymethyl chitosan (OCMC) Schiff's base was utilized for a new class of organic-inorganic hybrid material by grafting it on nano-silica-silane and further metallated with Cu (II). Here (3-Aminopropyl) triethoxysilane (APTES) was used as a linker and 2-hydroxy-1-naphthaldehyde (HN) for Schiff's base formation. The hybrid was characterized by FTIR, TGA, powder XRD, SEM, CHN, DLS, ICP-AES, diffuse reflectance UV-vis and EDX spectroscopic techniques. Magnetization measurements were carried out by VSM at room temperature. This study explored the possible synergic effect of unique properties of carboxymethyl chitosan, Schiff's base Cu (II) complex and nano-silica towards antibacterial activity and in dye degradation studies. The antibacterial performance of nano-hybrid material was examined against both Gram-positive (Escherichia coli) and Gram-negative (Bacillus subtilis) bacteria. The catalytic activity of the hybrid was tested for degradation of reactive black 5 (RB5) through advanced oxidation processes using H2O2 as oxidant. The results show a high dye degradation efficiency of 93% in 130min by the hybrid catalyst with reusability. As per published reports, Chitosan-Schiff's bases show strong antimicrobial activity and their Cu complexes exhibit good catalytic and anticancer activities. Therefore, it is expected that the new organic-inorganic hybrid would be highly applicable in environmental as well as biomedical fields.

Phenolic compounds based conjugates from dextran aldehyde and BSA: Preparation, characterization and evaluation of their anti-cancer efficacy for therapeutic applications.

Here, we have synthesized phenolic compounds (pc) based on conjugates from dextran aldehyde (dex-ald) and bovine serum albumin (BSA) and screening their potential activity as therapeutic agents in cancer disease. The synthesized conjugates were analyzed by UV-vis, FT-IR, XRD and SEM analysis. UV-vis spectra of conjugates showed the shifting of spectral peak at UV to visible region revealed the enhanced conjugation due to formation of linkage. The XRD peaks of conjugates found broader and indicating the amorphous phase of conjugating materials in compared to free components. The SEM images showed that the conjugated materials having numerous pores on its surface, which proved its porous nature. The amount of phenolic compounds conjugated with (dex-ald-pc) and (BSA-pc) were found to be 65.4 and 73.91mg/g of conjugates, respectively. Cells viability was significantly decreased approximately 80-85% at concentration of 100µg conjugates whereas the free polymers or phenolics did not affect the viability of cancer cells. Generation of high quantity of reactive oxygen species (ROS) in cells treated with conjugate materials, which may caused cell apoptosis in cancer cell line. The results clearly showed that conjugation of phenolic compounds were an effective method to improve the functional properties for therapeutic applications.

Self-assembling N-(9-Fluorenylmethoxycarbonyl)-l-Phenylalanine hydrogel as novel drug carrier.

Supramolecular hydrogel as a novel drug carrier was prepared from N-(9-Fluorenylmethoxycarbonyl) (Fmoc) modified l-phenylalanine. Its different properties like stability at different pH, temperature and rheology were evaluated in reference to salicylic acid (SA) as a model drug, entrapped in the supramolecular hydrogel network. The release behaviour of SA drug in supramolecular hydrogel was investigated by UV-vis spectroscopy. The influence of hydrogelator, pH values of the accepting media, temperature and concentration of SA drug on the release behaviour was investigated under static conditions. The results indicated that the release rate of SA in the supramolecular hydrogels was slightly retarded with an increase of the hydrogelator concentration. Also, the release rates of SA increased with an increase of temperature and its concentration. Furthermore, the release behaviour of SA was found to be different at various pH values in buffers. The study of the release kinetics indicated that the release behaviour of SA from the carrier was in accord with the Peppas model and the diffusion controlled mechanism involved in the Fickian model.

Dibutyrylchitin nanoparticles as novel drug carrier.

Chitin is a ubiquitous renewable biopolymer that is significantly distributed in the natural world. Biopolymeric nanoparticles (Nps) have been developed for various biomedical applications by researchers. Here, chitin derivative, dibutyrylchitin Nps (DBC) was synthesized as a nanocarrier for drug delivery using butyric anhydride and perchloric acid as a catalyst under heterogeneous conditions. The structural characterization was analyzed by FT-IR and FE SEM study showed spherical particles in a size range of 80-90 nm. The physiochemical evaluation involves swelling behavior and in vitro biodegradation studies. The results of in vitro hemolytic assay validate the blood compatibility of the prepared system. Drug release profiles indicate that 5-flourouracil (Fu) loaded dibutyrylchitin Nps (DBC-Fu) gives the enhanced drug release in acidic pH when compared to neutral pH. The encapsulation efficiency of DBC-Fu was found to be 90%. The confocal analysis also confirmed the uptake of both DBC and DBC-Fu Nps by A549 cell lines. Hence, this study shows that the DBC have the potential to be used as a drug carrier and also for other biomedical applications.

Antibacterial activity of diisocyanate-modified chitosan for biomedical applications.

A diisocyanate-modified chitosan (DIMC) was synthesized via a cross-linking reaction with chitosan and diphenyl methane diisocyanate. The structural and thermal properties of the DIMC were systematically characterized by FTIR, UV-vis, TGA, DSC, XRD and SEM. In addition, the optical properties were evaluated by photoluminescence. Finally, the antibacterial activities of the synthesized DIMC were examined against Escherichia coli and Staphylococcus pyogenes bacteria by agar plate diffusion method. The DIMC showed better degree of bacterial growth inhibition against E. coli as compared with unaltered chitosan. These results suggest that the synthesized chitosan xerogel could be used as a novel biodegradable material with improved antibacterial properties for biomedical applications.

Chitosan-PVP-nano silver oxide wound dressing: in vitro and in vivo evaluation.

The main aim of this work was to prepare wound healing material with chitosan, poly vinyl pyrrolidone (PVP), silver oxide nanoparticles. The prepared chitosan, chitosan-PVP-nano silver oxide (CPS) films were characterized for their thermal behaviour, morphological properties, mechanical properties, antibacterial properties and wound healing properties. The CPS film found higher antibacterial activity because the materials both chitosan as well as silver oxide poses good antibacterial activity. L929 cell lines were for cytotoxicity study and Adult male albino rats (140-180 g) were used for wound healing study. The prepared film has more wound healing property than of cotton gauge, 100% chitosan and other reported chitosan based dressings.

Chitosan silk-based three-dimensional scaffolds containing gentamicin-encapsulated calcium alginate beads for drug administration and blood compatibility.

In the present study gentamicin was encapsulated within calcium alginate beads and incorporated into porous chitosan, gelatin, double-hybrid silk fibroin, chitosan/gelatin and double-hybrid silk fibroin/chitosan scaffolds. Physiochemical, morphological and biological properties of fabricated amenable model systems were evaluated, revealing hemocompatible nature of double-hybrid silk fibroin/chitosan and double-hybrid silk fibroin scaffolds of hemolysis %<5 and porosity >85%. Fourier transform infrared results confirmed the blend formation and scanning electron microscope images showed good interconnectivity. Double-hybrid silk fibroin/chitosan-blended scaffold shows higher compressive strength and compressive modulus than other fabricated scaffolds. A comparative drug release profile of fabricated scaffolds revealed that double-hybrid silk fibroin/chitosan scaffold is a pertinent model system because of its prolonged drug release, optimal hemocompatability and high compressive modulus.

Cu-Ni nanoparticle-decorated graphene based photodetector.

We report a simple and straight forward approach for the synthesis of Cu-Ni graphene hybrid nano-composites. These nano-composites have been characterized using AFM, XRD, FTIR spectroscopy and HRTEM. The characterization data clearly shows uniform decoration of Cu-Ni nanoparticles on graphene layers. A thin film of these nano-composites was found to exhibit unique electrical and photoresponse properties, which may be attributed to photothermoelectric and photovoltaic effects. The photocurrent measurements indicate superior light absorption and long lifetime of this device.

Highly luminescent chitosan-L-cysteine functionalized CdTe quantum dots film: synthesis and characterization.

The present work describes synthesis of water soluble L-cysteine-functionalized CdTe quantum dots (QDs) with size tunable emission at different time intervals for chitosan based film. The characterization of the synthesized CdTe QDs-chitosan film was made by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA) and scanning electron microscope (SEM). The optical property of CdTe QDs-chitosan film was determined by UV-vis and photo-luminescence (PL) spectroscopy whereas their antibacterial activity was screened for Gram positive (Staphylococcus aureus) as well as Gram negative (Pseudomonas aurigionasa and Escherichia coli) bacteria by disc diffusion method. The loss of tunable light emission effect of QDs as well as the positive result of antibacterial study reveals that the synthesized QDs based chitosan film is a promising candidate for wide range of biomedical applications.

In vivo evaluation of chitosan-PVP-titanium dioxide nanocomposite as wound dressing material.

In our present study, the blends of chitosan, poly(N-vinylpyrrolidone) (PVP) and titanium dioxide (TiO2) were investigated by Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The size distribution of the TiO2 nanoparticles was measured using transmission electron microscope and scanning electron microscope. The studies on the mechanical properties of composite material indicate that the addition of TiO2 nanoparticles increases its strength. The prepared nanocomposite dressing has excellent antimicrobial efficacy and good biocompatibility against NIH3T3 and L929 fibroblast cells. Compared to conventional gauze, soframycin skin ointment and chitosan treated groups, the prepared nano dressing caused an accelerated healing of open excision type wounds in albino rat model. The synergistic effects of nanocomposite dressing material like good antibacterial ability, high swelling properties, high WVTR, excellent hydrophilic nature, biocompatibility, wound appearance and wound closure rate through in vivo test makes it a suitable candidate for wound healing applications.