Hydrolyzed collagen-grafted-poly[(acrylic acid)-co -(methacrylic acid)] hydrogel for drug delivery

Silver Nanoparticle Incorporated Human Amniotic Membrane Gel Accelerates Second-Degree Burn Wound Healing in Wister Rat

Burn has terrible consequences for the affected patients, making them vulnerable to wound infections and septicemia, which results in physical and mental disability and death, necessitating superior treatment options. Human amniotic membrane (HAM) has been utilized in burn wounds for decades for its low immunogenicity, angiogenic, anti-inflammatory, and antimicrobial properties and for promoting epithelialization. Silver nanoparticles (AgNPs), on the other hand, have antimicrobial properties and promote fibroblast migration. This study aimed to determine the burn wound healing potential of HAM + AgNPs. The gel was prepared using HAM (1% and 2%), AgNPs, carbopol 934, acrylic acid, glycerine, and triethanolamine, and different physical properties (pH, water absorption, swelling variation, spreadability, etc.) of the gel were determined; nuclear magnetic resonance (NMR) spectroscopy, antibacterial activity, brine shrimp lethality test, and histopathological observation were conducted. In vivo studies with Wistar rats demonstrated better healing capabilities than individual components of the gel. Wound contraction percentage after 20 days was 96.1 ± 0.27% which was highly significant (p < 0.0001), and the epithelialization period was 23.67 ± 2.05 days (p < 0.01) for HAM + AgNPs which was preferable to the positive control, AgNPs, HAM, and negative control; also, the histopathologic observation using hematoxylin and eosin, and Masson's trichrome staining were showed the better healing progress for HAM + AgNPs. Both HAM and AgNPs had antibacterial activities against gram-positive and gram-negative bacteria. These results indicated that the formulated HAM + AgNPs gel had remarkable effectiveness in burn wound healing compared to others. Further studies will be conducted to determine the molecular mechanism behind wound healing.

Mucoadhesive carriers for oral drug delivery

Among the various dosage forms, oral medicine has extensive benefits including ease of administration and patients' compliance, over injectable, suppositories, ocular and nasal. Despite of extensive demand and emerging advantages, over 50% of therapeutic molecules are not available in oral form due to their physicochemical properties. More importantly, most of the biologics, proteins, peptide, and large molecular drugs are mostly available in injectable form. Conventional oral drug delivery system has limitation such as degradation and lack of stability within stomach due to presence of highly acidic gastric fluid, hinders their therapeutic efficacy and demand more frequent and higher dosing. Hence, formulation for controlled, sustained, and targeted drug delivery, need to be designed with feasibility to target the specific region of gastrointestinal (GI) tract such as stomach, small intestine, intestine lymphatic, and colon is challenging. Among various oral delivery approaches, mucoadhesive vehicles are promising and has potential for improving oral drug retention and controlled absorption to treat local diseases within the GI tract, as well systemic diseases. This review provides the overview about the challenges and opportunities to design mucoadhesive formulation for oral delivery of therapeutics in a way to target the specific region of the GI tract. Finally, we have concluded with future perspective and potential of mucoadhesive formulations for oral local and systemic delivery.

New Developments in Medical Applications of Hybrid Hydrogels Containing Natural Polymers

New trends in biomedical applications of the hybrid polymeric hydrogels, obtained by combining natural polymers with synthetic ones, have been reviewed. Homopolysaccharides, heteropolysaccharides, as well as polypeptides, proteins and nucleic acids, are presented from the point of view of their ability to form hydrogels with synthetic polymers, the preparation procedures for polymeric organic hybrid hydrogels, general physico-chemical properties and main biomedical applications (i.e., tissue engineering, wound dressing, drug delivery, etc.).

Hydrolyzed Collagen-Sources and Applications

Hydrolyzed collagen (HC) is a group of peptides with low molecular weight (3-6 KDa) that can be obtained by enzymatic action in acid or alkaline media at a specific incubation temperature. HC can be extracted from different sources such as bovine or porcine. These sources have presented health limitations in the last years. Recently research has shown good properties of the HC found in skin, scale, and bones from marine sources. Type and source of extraction are the main factors that affect HC properties, such as molecular weight of the peptide chain, solubility, and functional activity. HC is widely used in several industries including food, pharmaceutical, cosmetic, biomedical, and leather industries. The present review presents the different types of HC, sources of extraction, and their applications as a biomaterial.

Choline supported poly(ionic liquid) graft copolymers as novel delivery systems of anionic pharmaceuticals for anti-inflammatory and anti-coagulant therapy

New type of carriers based on grafted poly(ionic liquid)s was designed for delivery of ionically attached salicylates (Sal). Choline derived ionic liquid monomeric units were successfully introduced with various content in the side chains by the controlled radical polymerization. Properly high amounts of ionic pharmaceutics in the polymer systems were achieved by the well-fitted length and grafting degree of the side chains. In aqueous solution the graft copolymers were self-assembled into the spherical superstructures with sizes up to 73 nm. Delivery studies showed "burst" release within 4 h, after that it was slower yielding ~70% of released drug within 80 h. Proposed nanocarriers supported low toxicity against human cells (NHDF and BEAS-2B), anti-inflammation activity evaluated with the use of pro-inflammatory interleukins (IL-6 and IL-8) and antibacterial activities towards E. coli. Adjustment of ionic drug content by structural parameters of graft copolymers, including grafting degree and graft length, are advantageous to tailor nanocarriers with self-assembly properties in aqueous media. Effective release process by ionic exchange and biological activity with low toxicity are promising for further development of this type of drug delivery (DDS).

A facile hydrothermal method-fabricated robust and ultralight weight cellulose nanocrystal-based hydro/aerogels for metal ion removal

Heavy metal ion contamination, in particular that associated with Pb²⁺, Cd²⁺, and Cu²⁺, poses a considerable threat to aquatic environments and human health. To obtain a highly efficient adsorbent, in this work, a facile hydrothermal method was applied to prepare acrylic acid grafted onto cellulose nanocrystal (AA-g-CNC) hydro/aerogel as an adsorbent for Pb²⁺, Cd²⁺, and Cu²⁺ removal. The obtained AA-g-CNC hydrogels withstood up to 0.821 MPa of compression and showed good reciprocating performance when the deformation reached 40%. The as-formed AA-g-CNC aerogels had highly porous honeycomb structure, with many functional groups and a high zeta potential, all of which are essential features for an effective adsorbent. The maximum Pb²⁺, Cd²⁺, and Cu²⁺ removal capacities of AA-g-CNC aerogels reached 1026, 898.8, and 872.4 mg/g respectively. Their adsorption followed the Freundlich isotherm model and fitted well with pseudo-second-order kinetic models. The adsorption mechanism mainly attributed to electrostatic chelation between metal ions with sulfonate and carboxylate groups.

Hydrothermal Synthesis of Cellulose Nanocrystal-Grafted-Acrylic Acid Aerogels with Superabsorbent Properties

In this work, we applied a fast and simple method to synthesize cellulose nanocrystal (CNC) aerogels, via a hydrothermal strategy followed by freeze drying. The characteristics and morphology of the obtained CNC-g-AA aerogels were affected by the hydrothermal treatment time, volume of added AA (acrylic acid), and the mass fraction of the CNCs. The formation mechanism of the aerogels involved free radical graft copolymerization of AA and CNCs with the cross-linker N,N'-methylene bis(acrylamide) (MBA) during the hydrothermal process. The swelling ratio of the CNC-g-AA aerogels was as high as 495:1, which is considerably greater than that of other polysaccharide-g-AA aerogels systems. Moreover, the CNC-g-AA aerogels exhibited an excellent methyl blue (MB) adsorption capacity and the ability to undergo rapid desorption/regeneration. The maximum adsorption capacity of the CNC-g-AA aerogels for MB was greater than 400 mg/g. Excellent regeneration performance further indicates the promise of our CNC-g-AA aerogels as an adsorbent for applications in environmental remediation.

Highly deformable hydrogels constructed by pH-triggered polyacid nanoparticle disassembly in aqueous dispersions

Most hydrogels are prepared using small-molecule monomers but unfortunately this approach may not be feasible for certain biomaterial applications. Consequently, alternative gel construction strategies have been established, which include using covalent inter-linking of preformed gel particles, or microgels (MGs). For example, covalently interlinking pH-responsive MGs can produce hydrogels comprising doubly crosslinked microgels (DX MGs). We hypothesised that the deformability of such DX MGs was limited by the presence of intra-MG crosslinking. Thus, in this study we designed new nanoparticle (NP)-based gels based on pH-swellable NPs that are not internally crosslinked. Two polyacid NPs were synthesised containing methacrylic acid (MAA) and either ethyl acrylate (EA) or methyl methacrylate (MMA). The PMAA-EA and PMAA-MMA NPs were subsequently vinyl-functionalised using glycidyl methacrylate (GMA) prior to gel formation via free-radical crosslinking. The NPs mostly disassembled on raising the solution pH but some self-crosslinking was nevertheless evident. The gels constructed from the EA- and MMA-based NPs had greater breaking strains than a control DX MG. The effect of varying the solution pH during curing on the morphology and mechanical properties of gels prepared using PMAA-MMA-GMA NPs was studied and both remarkable deformability and excellent recovery were observed. The gels were strongly pH-responsive and had tensile breaking strains of up to 420% with a compressive strain-at-break of more than 93%. An optimised formulation produced the most deformable and stretchable gel yet constructed using NPs or MGs as the only building block.