Silk industry waste protein: isolation, purification and fabrication of electrospun silk protein nanofibers as a possible nanocarrier for floating drug delivery

Silver nanoparticles loaded triple-layered cellulose-acetate based multifunctional dressing for wound healing

Chronic wounds present considerable challenges which delay their effective healing. Currently, there are several biomaterial-based wound dressings available for healing diverse wound types. However, most of commercial wound dressings are too expensive to be affordable to the patients belonging to the middle and lower socioeconomic strata of the society. Thus, in this investigation affordable triple layered nanofibrous bandages were fabricated using the layer-by-layer approach. Here, the topmost layer comprised of a hydrophilic poly vinyl alcohol layer, cross-linked with citric acid. The middle layer comprising of cellulose acetate was loaded with silver nanoparticles as an antibacterial agent, while the lowermost layer was fabricated using hydrophobic polycaprolactone. The triple-layered nanofibrous bandages having a nano-topography, exhibited a smooth, uniform and bead-free morphology, with the nanofiber diameter ranging between 200 and 300 nm. The nanofibers demonstrated excellent wettability, slow in vitro degradation, controlled release of nano‑silver and potent antibacterial activity against Gram-negative (E.coli) and Gram-positive (S. aureus) bacteria. The fabricated bandages had excellent mechanical strength upto 12.72 ± 0.790 M. Pa, which was suitable for biomedical and tissue engineering applications. The bandage demonstrated excellent in vitro hemocompatibility and biocompatibility. In vivo excisional wound contraction, along with H and E and Masson's Trichrome staining further confirmed the potential of the nanofibrous bandage for full-thickness wound healing. Pre-clinical investigations thus indicated the possibility of further evaluating the triple-layered nanofibrous dressing in clinical settings.

Novel therapeutic approach for the treatment of cystic fibrosis based on freeze-dried tridrug microparticles to treat cystic fibrosis

BACKGROUND

Cystic fibrosis is a severe, autosomal recessive disease that shortens life expectancy. According to studies, approximately 27% of patients with CF aged 2-5 years and 60 to 70% of adult patients are infected with P. aeruginosa. The patients experience bronchospasm leading to a persistent contracted state of the airways.

OBJECTIVES

The current work explores the possibility of combining ivacaftor and ciprofloxacin to combat the bacteria. A third drug L-salbutamol would be coated onto the surface of the drug-entrappped microparticles to instantaneously provide relief from bronchoconstriction.

METHODS

The microparticles were prepared using bovine serum albumin and L-leucine using the freeze-drying approach. The process and formulation parameters were optimized. The prepared microparticles were surface coated by L-salbutamol using the dry-blending method. The microparticles were subjected to rigorous in-vitro characterization for entrapment, inhalability, antimicrobial activity, cytotoxicity study and safety. The performance of the microparticles to be loaded into a inhaler was checked by the Anderson cascade impactor.

RESULTS

The freeze-dried microparticles had a particle size of 817.5 ± 5.6 nm with a polydispersity ratio of 0.33. They had a zeta potential of -23.3 ± 1.1 mV. The mass median aerodynamic diameter of the microparticles was 3.75 ± 0.07 μm, and the geometric standard diameter was 1.66 ± 0.033 μm. The microparticles showed good loading efficiency for all three drugs. DSC, SEM, XRD, and FTIR studies confirmed the entrapment of ivacaftor and ciprofloxacin. SEM and TEM scans observed the shape and the smooth surface. Antimicrobial synergism was proven by the agar broth, and dilution technique and the formulation was deemed safe by the results of the MTT assay.

CONCLUSION

Freeze-dried microparticles of ivacaftor, ciprofloxacin, and L-salbutamol could pave way to a hitherto unexplored combination of drugs as a novel approach to treat P. aeruginosa infcetions and bronchoconstriction commonly associated with cystic fibrosis.

Progress in recycling and valorization of waste silk

Due to the improvements in living standards and the "throw away" culture of mankind, large amount of waste textiles is constantly generated. In particular, silk is an abundant high-grade textile material with characteristics of wear comfort, high profit, and low supply with high demand, but it transforms into waste when discarded. This paper reviews the current progress of recycling and reuse of waste silk from the aspects of energy, yarn and fabric, reinforcement of composites, silk fibroin, biological tissue engineering, filtration of air and water, and electrode. The modification, optimization and application of regenerated silk fibroin extracted from waste silk are promising to industrialization and sustainable development. Making waste silk functional and intelligently wearable are two ways of recycling waste silk with low cost and high return value in the near future. The recovery and utilization of waste silk provide a paradigm for valorization of other fiber-based waste such as wool, cotton, bast and synthetic fibers.

Natural protein-based electrospun nanofibers for advanced healthcare applications: progress and challenges

Electrospinning is an electrostatic fiber fabrication technique that operates by the application of a strong electric field on polymer solution or melts. It is used to fabricate fibers whose size lies in the range of few microns to the nanometer range. Historic development of electrospinning has evinced attention due to its outstanding attributes such as small diameter, excellent pore inter-connectivity, high porosity, and high surface-to-volume ratio. This review aims to highlight the theory behind electrospinning and the machine setup with a detailed discussion about the processing parameters. It discusses the latest innovations in natural protein-based electrospun nanofibers for health care applications. Various plant- and animal-based proteins have been discussed with detailed sample preparation and corresponding processing parameters. The usage of these electrospun nanofibers in regenerative medicine and drug delivery has also been discussed. Some technical innovations in electrospinning techniques such as emulsion electrospinning and coaxial electrospinning have been highlighted. Coaxial electrospun core-shell nanofibers have the potential to be utilized as an advanced nano-architecture for sustained release targeted delivery as well as for regenerative medicine. Healthcare applications of nanofibers formed via emulsion and coaxial electrospinning have been discussed briefly. Electrospun nanofibers have still much scope for commercialization on large scale. Some of the available wound-dressing materials have been discussed in brief.

Facile one pot microbe-mediatedin situsynthesis and antibacterial activity of reduced graphene oxide-silver nanocomposite

The present research deals with the development of a novel bioinspiredin situfabrication of reduced graphene oxide (rGO)-silver nanoparticle (AgNPs) nanocomposite (rGO@AgNCs) using microbes namelyPseudomonas aeruginosa(PA) andStaphylococcus aureus(SA). The fabricated rGO@AgNCs were characterized using Ultraviolet-visible (UV-Vis) spectroscopy, Fourier-transform infrared spectroscopy (FTIR), particle size analysis, polydispersity index (PDI), zeta potential analysis, energy dispersive x-ray analysis (EDAX), Raman spectroscopy, powder x-ray diffraction (PXRD), high-resolution transmission electron microscopy (HR-TEM) analysis, etc. Furthermore, the rGO@AgNCs-PA and rGO@AgNCs-SA interaction with serum protein, pH stability study, andin vitrodissolution of AgNPs were also performed. The research findings of the proposed study demonstrated the simultaneous reduction of graphene oxide (GO) and AgNPs and the formation of rGO@AgNCs in the presence of microbes. Thein vitrodissolution studies of rGO@AgNCs composites showed better AgNPs dissolution with controlled release and offered remarkable matrix integrity throughout the dissolution period. The size and stability of rGO@AgNCs-PA and rGO@AgNCs-SA had no significant changes at physiological pH 7.4. A minimal decrease in the zeta potential of rGO@AgNCs was observed, which may be due to the weak interaction of nanocomposites and albumin. The antibacterial application of the synthesized nanocomposite was evaluated against a pathogenic mastitis-forming bacterium. The obtained results suggested an admirable antibacterial activity of synthesized nanocomposites against the tested microbes. This knowledge will assist the scientific fraternity in designing novel antibacterial agents with enhanced antibacterial activity against various veterinary pathogens in near future.

Polysaccharide-Based Materials Created by Physical Processes: From Preparation to Biomedical Applications

Polysaccharide-based materials created by physical processes have received considerable attention for biomedical applications. These structures are often made by associating charged polyelectrolytes in aqueous solutions, avoiding toxic chemistries (crosslinking agents). We review the principal polysaccharides (glycosaminoglycans, marine polysaccharides, and derivatives) containing ionizable groups in their structures and cellulose (neutral polysaccharide). Physical materials with high stability in aqueous media can be developed depending on the selected strategy. We review strategies, including coacervation, ionotropic gelation, electrospinning, layer-by-layer coating, gelation of polymer blends, solvent evaporation, and freezing-thawing methods, that create polysaccharide-based assemblies via in situ (one-step) methods for biomedical applications. We focus on materials used for growth factor (GFs) delivery, scaffolds, antimicrobial coatings, and wound dressings.

Pharmaceutical applications of citric acid

Background

Citric acid (CA) is a universal plant and animal-metabolism intermediate. It is a commodity chemical processed and widely used around the world as an excellent pharmaceutical excipient. Notably, CA is offering assorted significant properties viz. biodegradability, biocompatibility, hydrophilicity, safety, etc. Therefore, CA is broadly employed in many sectors including foodstuffs, beverages, pharmaceuticals, nutraceuticals, and cosmetics as a flavoring agent, sequestering agent, buffering agent, etc. From the beginning, CA is a regular ingredient for cosmetic pH-adjustment and as a metallic ion chelator in antioxidant systems. In addition, it is used to improve the taste of pharmaceuticals such as syrups, solutions, elixirs, etc. Furthermore, free CA is also employed as an acidulant in mild astringent preparations.

Main text

In essence, it is estimated that the functionality present in CA provides excellent assets in pharmaceutical applications such as cross-linking, release-modifying capacity, interaction with molecules, capping and coating agent, branched polymer nanoconjugates, gas generating agent, etc. Mainly, the center of attention of the review is to deliver an impression of the CA-based pharmaceutical applications.

Conclusion

In conclusion, CA is reconnoitered for multiple novels pharmaceutical and biomedical/applications including as a green crosslinker, release modifier, monomer/branched polymer, capping and coating agent, novel disintegrant, absorption enhancer, etc. In the future, CA can be utilized as an excellent substitute for pharmaceutical and biomedical applications.

Graphical abstract