Recent Advances in Chitosan-Based Applications-A Review

Chitosan derived from chitin gas gathered much interest as a biopolymer due to its known and possible broad applications. Chitin is a nitrogen-enriched polymer abundantly present in the exoskeletons of arthropods, cell walls of fungi, green algae, and microorganisms, radulae and beaks of molluscs and cephalopods, etc. Chitosan is a promising candidate for a wide variety of applications due to its macromolecular structure and its unique biological and physiological properties, including solubility, biocompatibility, biodegradability, and reactivity. Chitosan and its derivatives have been known to be applicable in medicine, pharmaceuticals, food, cosmetics, agriculture, the textile and paper industries, the energy industry, and industrial sustainability. More specifically, their use in drug delivery, dentistry, ophthalmology, wound dressing, cell encapsulation, bioimaging, tissue engineering, food packaging, gelling and coating, food additives and preservatives, active biopolymeric nanofilms, nutraceuticals, skin and hair care, preventing abiotic stress in flora, increasing water availability in plants, controlled release fertilizers, dye-sensitised solar cells, wastewater and sludge treatment, and metal extraction. The merits and demerits associated with the use of chitosan derivatives in the above applications are elucidated, and finally, the key challenges and future perspectives are discussed in detail.

Electrochemical sensing platform for the simultaneous femtomolar detection of amlodipine and atorvastatin drugs

The development of a proficient and ultra-high sensitive functionalized electrode for accurate analysis of drugs is a long-standing challenge. Herein, we report an electrochemical nanocomposite scaffold, comprising of silver nanoparticles integrated with functionalized carbon nanotubes (COOH-CNTs/Ag/NH₂-CNTs) for the simultaneous quantification of two widely used amlodipine (AM) and atorvastatin (AT) drugs. The sandwiched nanocomposite materials were thoroughly characterized morphologically and structurally. The nanocomposite COOH-CNTs/Ag/NH₂-CNTs immobilized over glassy carbon electrode catalyzed electron transfer reactions at the electrode–electrolyte interface and facilitated detection of targeted drugs, as revealed by the significant decrease in oxidation potentials at 879 mV and 1040 mV and improved current signals. Electrochemical characterization and testing show that the functionalized porous architecture with a large effective surface area is a promising scaffold for the sensing of a binary mixture of AM and AT with limits of detection in the femtomolar range (77.6 fM, and 83.2 fM, respectively). Besides, the specificity, stability, and reliability of the electrochemical sensing platform in simple and complex biological and pharmaceutical samples with high percentage recoveries highlight its scope for practical applications. Computational studies supported the experimental outcomes and offered insights about the role of modifier in facilitating electron transfer between transducer and analytes.

Development of an ultra-sensitive electrochemical platform for the simultaneous detection of two high blood pressure drugs.

The antimicrobial activity of silver nanoparticles biocomposite films depends on the silver ions release behaviour

This study aimed to investigate the release of silver ions from the packaging, their diffusion within a food hydrogel and the effect on the growth of Pseudomonas fluorescens. Biosorbed-silver nanoparticles (BSNPs) were synthesized using a plant extract and were incorporated into chitosan or poly (vinyl alcohol) polymer to prepare biocomposite films. The addition of BSNPs improved the physical and antimicrobial properties of the films as shown by tensile strength and inhibition of P. fluorescens in hydrogels, respectively. PVA based BSNPs film showed a stronger antimicrobial effect, compared to chitosan based BSNPs film and this correlated with a higher amount of silver ions release from the PVA film into the hydrogel. Results suggest that the strength of the interaction between BSNPs and the film polymer is the key factor leading to the difference in the release behaviour of the antimicrobials, which in turn determines the antimicrobial activity of the active packaging.

Rhus and Safflower Extracts as Potential Novel Food Antioxidant, Anticancer, and Antimicrobial Agents Using Nanotechnology

Green synthesis of metal nanoparticles using plant extracts offers a safe and attractive alternate to the chemical methods. The present work aims at preparing metal nanoparticles of rhus (Rhus coriaria L.) and safflower (Carthamus tinctorius L.) extracts using Fe²⁺, Cu²⁺, Zn²⁺, and Ag⁺ ions. The water extracts were prepared, and the total polyphenols and flavonoids contents were determined. The safflower extract contained the highest number of total polyphenols and total flavonoids (87.20 mg GAE/g and 36.32 mg QE/g), respectively. The synthesized nanoparticles were characterized using UV-Visible (UV-Vis) spectroscopy and Transmission Electron Microscope (TEM). The studied extracts and their nanoparticles were evaluated as an antioxidant, antimicrobial, and anticancer agents. The plant extracts and their nanoparticles showed significant antioxidant activity using (3-ethylbenzothiazoline-6-sulfonic acid (ABTS^•+) and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assays. Safflower silver nanoparticles (AgNPs) were the most powerful antimicrobial agent compared to the other nanoparticles. The Sulforhodamine B (SRB) cytotoxic activity was evaluated against three cancer cell lines. The results revealed that CuNP safflower nanoparticles displayed the highest activity as anticancer agent with values (98.94% with T47D, 97.68% with HEPG2, and 89.33% against Caco-2). The data revealed that rhus and safflower extracts and their nanoparticles possess high potential activity as antimicrobial, antioxidant, and anticancer agents.

Photobiologic-mediated fabrication of silver nanoparticles with antibacterial activity

We present the simple, eco-friendly synthesis of silver nanoparticles (AgNPs) using sunlight or green, red, blue, or white LED light together with Dryopteris crassirhizoma rhizome extract (DCRE) as the reducing and capping agent. The preliminary indication of AgNP production was a color change from yellowish green to brown after light exposure in the presence of DCRE. Optimization of parameters such as pH, inoculum dose, and metal ion concentration played an important role in achieving nanoparticle production in 30min. The spectroscopic and morphological properties of AgNPs were characterized using UV-Vis spectroscopy through the presence of a characteristic surface plasmon resonance (SPR) band for AgNPs, Fourier transform infrared spectroscopy (FT-IR), high-resolution transmission electron microscopy (HR-TEM), and X-ray diffraction (XRD). The FT-IR results indicated that the phytochemical present in DCRE was the probable reducing/capping agent involved in the synthesis of AgNPs, and light radiation enhanced nanoparticle production. HR-TEM revealed that the AgNPs were almost spherical with an average size of 5-60nm under all light sources. XRD studies confirmed the face cubic center (fcc) unit cell structure of AgNPs. The synthesized AgNPs showed good antimicrobial activity against Bacillus cereus and Pseudomonas aeruginosa. This study will bring a new insight in ecofriendly production of metal nanoparticles.