Nabanita Saha

Development and Characterization of Novel Medicated Hydrogels for Wound Dressing

The medicated hydrogels were prepared aseptically under moist heat treatment using polyvinylpyrrolidone (PVP), sodium-carboxymethylcellulose (CMC), polyethyleneglycol (PEG), agar, glycerin and/or boric acid (BA) and designated as PVP-CMC and PVP-CMC-BA. The aim of this study was to develop some medicinal values–based hydrogels. BA was used to build up the medicinal values (antiseptic and antimicrobial properties) within the hydrogels. Optical images, scanning electron microscopy (SEM), and Fourier transform infrared (FTIR) spectroscopy of the hydrogels indicated that boric acid is uniformly dispersed within the cross-linked hydrogel network that may heal and protect the wounds from infections/sepsis. Swelling study in presence of water and physiological saline solution confirmed its reasonable absorption capacity. The rheological properties and mechanical properties demonstrated that the boric acid incorporated hydrogels are quite flexible. Assessment of antimicrobial property study proves that PVP-CMC-BA (3% BA) has strong infection protection capacity.

Hydrothermal effect and mechanical stress properties of carboxymethylcellulose based hydrogel food packaging.

The PVP-CMC hydrogel film is biodegradable, transparent, flexible, hygroscopic and breathable material which can be used as a food packaging material. The hygroscopic character of CMC and PVP plays a big role in the changing of their mechanical properties where load carrying capacity is one of important criteria for packaging materials. This paper reports about the hydrothermal effect on the mechanical and viscoelastic properties of neat CMC, and PVP-CMC (20:80) hydrogel films under the conditions of combined multiple stress factors such as temperature, time, load, frequency and humidity. The dry films were studied by transient and dynamic oscillatory experiments using dynamic mechanical analyser combined with relative humidity chamber (DMA-RH). The mechanical properties of PVP-CMC hydrogel film at room temperature (25 °C), in the range of 0-30%RH remain steady. The 20 wt% of PVP in PVP-CMC hydrogel increases the stiffness of CMC from 2940 to 3260 MPa at 25 °C and 10%RH.

Preparation and Characterization of Poly (vinyl alcohol)/Lactic Acid Compounded Polymeric Films

Abstract Poly (vinyl alcohol) (PVA) and L-lactic acid (LA) were compounded to get biodegradable polymeric film with useful mechanical, thermal, and bacteriostatic properties for possible medical or packaging applications. Samples with various concentrations of LA were prepared by using the solvent cast technique and characterized by tensile tests, differential scanning calorimetry, Fourier-transform infrared spectroscopy, thermogravimetry, evolved gas analysis, and bacteriostatic tests, and their biodegradability was investigated under aquatic and aerobic conditions. The films show a rapid increase in elasticity and decrease in glass transition temperatures due to the presence of LA. A bacteriostatic effect on Pseudomonas putida, Staphylococcus epidermis, and Micrococcus sp. was proved. The biodegradation of all samples by mixed microflora was completed within 250 hours; however, the course of biodegradation was influenced by both esterification of PVA and the presence of molecules of LA in the polymeric films.

Significant Characteristics of Medical-Grade Polymer Sheets and their Efficiency in Protecting Hydrogel Wound Dressings: A Soft Polymeric Biomaterial

Hydrogel dressings are soft biomaterials that need protection from external influences. Polymer sheets such as breathable film (BF) or breathable laminate (BL) were characterized in respect of water vapor transmission, water contact angle, microbial penetrability, and antimicrobial property to protect hydrogel dressings. The mechanical property and water retention ability of hydogels PVP-CMC and PVP-CMC-BA with and without BF and BL have been examined. Hydrogels covered with either BF or BL show better mechanical flexibility; however, their water retention capacity increases reasonably. The determined efficient properties of polymer sheets established that BF is better than BL as a protective sheet cover for hydrogel dressings.

Modification of poly(vinyl alcohol) with lactose and calcium lactate: potential filler from dairy industry

Abstract Characteristics of a newly developed environmentally friendly biocomposite material, poly(vinyl alcohol) (PVA) modified with lactose and calcium lactate, potential fillers, byproduct of dairy industry, are reported in the present paper. Sample films containing 0, 10, 20, 33 and 42 wt-% of filler were prepared by conventional solvent casting into acrylic plates. Morphological, mechanical and thermal properties of PVA, PVA–lactose and PVA–calcium lactate composites were studied by optical microscopy, stress–strain analysis, Fourier transform infrared spectroscopy–attenuated total reflectance (FTIR–ATR), differential scanning calorimetry, thermogravimetric analysis (TGA), and also the biodegradability was tested. The films were thin and transparent, and became gradually white with increasing concentration of the filler. Optical microscopy and FTIR–ATR analysis of PVA–lactose and PVA–calcium lactate confirmed that they are composite materials. Their mechanical properties increased up to 33 wt-% filler. The glass transition temperature also decreased with rising content of filler, which indicates the influence of moisture absorbed by the composites (confirmed by TGA measurements). Poly(vinyl alcohol) modification with lactose showed that the biodegradability is improved in aqueous environment.

Ecofriendly Synthesis of Silver Nanoparticles from Garden Rhubarb (Rheum rhabarbarum)

Bioreduction of silver ions following one pot process is described to achieve Rheum rhabarbarum (RR) based silver nanoparticles (SNPs) which is termed as “RR-SNPs.” The Ultraviolet–visible spectroscopy (UV–vis) confirms the characteristic surface plasmon resonance band for RR-SNPs in the range of 420–460 nm. The crystalline nature of SNPs was confirmed by X-ray diffraction (XRD) peaks at 38.2°, 45.6°, 64.2°, and 76.8°. Transmission electron microscopy (TEM) and scanning electronic microscopy (SEM) confirm the shape of synthesized SNPs. They are roughly spherical but uniformly distributed, and size varies from 60 to 80 nm. These biogenic SNPs show persistent zeta potential value of 34.8 mV even after 120 days and exhibit potent antibacterial activity in presence of Escherichia coli (CCM 4517) and Staphylococcus aureus (CCM 4516). In addition, cytotoxicity of RR-SNPs against in vitro human epithelial carcinoma (HeLa) cell line showed a dose-response activity. The lethal concentration (LC50) value was found to be 28.5 μg/mL for RR-SNPs in the presence of HeLa cells. These findings help us to evaluate their appropriate applications in the field of nanotechnology and nanomedicine.

Stability Study of Novel Medicated Hydrogel Wound Dressings

PVP-CMC and PVP-CMC-BA hydrogels were prepared for biomedical applications. These hydrogels were stored under 5°C ± 2°C, 22°C ± 3°C, and 40°C for 180 days to identify their suitable storage condition. At 5°C ± 2°C, hydrogels showed minimum alteration in physical properties. No microbial colonies appeared on PVP-CMC stored at 5°C ± 2°C, but they slowly appeared at 22°C ± 3°C and 40°C after 45 days. FTIR and antibacterial assay demonstrated that boric acid (BA) in hydrogel remained stable for 180 days. PVP-CMC-BA is more bio-stable than PVP-CMC because of BA, an antibacterial agent. Finally, 5°C ± 2°C was recommended as the best storage condition for both PVP-CMC and PVP-CMC-BA hydrogels.

Preparation of bacterial cellulose based hydrogels and their viscoelastic behavior

Bacterial cellulose (BC) based hydrogels have been prepared in blended with carboxymethylcellulose and polyvinyl pyrrolidone by using heat treatment. The properties of BC-CMC and BC-PVP hydrogels were compared with pure BC, CMC and PVP hydrogels. These hydrogels were investigated by measuring their structural, morphological and viscoelastic properties. Through the morphological images, alignment of the porous flake like structures could be seen clearly within the inter-polymeric network of the hydrogels. Also, the detail structure analysis of the polymers blended during the hydrogel formation confirms their interactions with each other were studied. Further, the viscoelastic behavior of all the hydrogels in terms of elastic and viscous property was studied. It is observed that at 1% strain, including CMC and PVP hydrogels, all the BC based hydrogels exhibited the linear trend throughout. Also the elastic nature of the material remains high compared to viscous nature. Moreover, the changes could be noticed in case of blended polymer based hydrogels. The values of complex viscosity (η*) decreases with increase in angular frequency within the range of ω = 0.1−100 rad.s−1.

A Highly Flexible Supercapacitor Based on MnO2/RGO Nanosheets and Bacterial Cellulose-Filled Gel Electrolyte

The flexible supercapacitors (SCs) of the conventional sandwich-type structure have poor flexibility due to the large thickness of the final entire device. Herein, we have fabricated a highly flexible asymmetric SC using manganese dioxide (MnO2) and reduced graphene oxide (RGO) nanosheet-piled hydrogel films and a novel bacterial cellulose (BC)-filled polyacrylic acid sodium salt-Na2SO4 (BC/PAAS-Na2SO4) neutral gel electrolyte. Apart from being environmentally friendly, this BC/PAAS-Na2SO4 gel electrolyte has high viscosity and a sticky property, which enables it to combine two electrodes together. Meanwhile, the intertangling of the filled BC in the gel electrolyte hinders the decrease of the viscosity with temperature, and forms a separator to prevent the two electrodes from short-circuiting. Using these materials, the total thickness of the fabricated device does not exceed 120 μm. This SC device demonstrates high flexibility, where bending and even rolling have no obvious effect on the electrochemical performance. In addition, owing to the asymmetric configuration, the cell voltage of this flexible SC has been extended to 1.8 V, and the energy density can reach up to 11.7 Wh kg−1 at the power density of 441 W kg−1. This SC also exhibits a good cycling stability, with a capacitance retention of 85.5% over 5000 cycles.

Properties of biomineralized (CaCO3) PVP-CMC hydrogel with reference to its cytotoxicity

ABSTRACT The authors focus on properties of biomineralized (CaCO3) PVP-CMC hydrogel (designated as I–X) including cytotoxicity assay using primary mouse embryonic fibroblasts. The biomineralized samples (VII–X) showed >80% cell viability, was selected for further characterizations. FTIR and XRD indicate deposition of CaCO3 within the PVP-CMC hydrogel matrix, SEM shows changes in morphology and pore diameter (VII and VIII: 1–12 µm; IX: 10–70 µm; X: 70–170 µm), TGA determines the decomposition scenario of CaCO3, and tensile strength of samples (VII–X) ranged between 0.04 and 1.0 GPa, which practically corresponds to the modulus of cancellous bone. GRAPHICAL ABSTRACT