Antibacterial hydrogel dressings and their applications in wound treatment

Antimicrobial hydrogels, both in semi-stiff sheets and amorphous form, have been extensively studied for wound management mainly owing to their high-water content, lower wound adherence, promoted autolysis debridement, epithelial migration, and granulation growth. Benefiting from the recent advances in materials science, biotechnology, and a growing understanding of wound microbiology, an extensive variety of antimicrobial hydrogels have been developed. These novel antimicrobial hydrogels can prevent and control microbial infection. In addition, they possess wound healing functions for improved wound management. This chapter will provide a comprehensive summary of the current studied antimicrobial hydrogels in literature and available hydrogel dressings in the market, including their design, fabrication method, and wound management efficacy in vitro or in vivo. The detailed and critical discussion of the advantages and disadvantages of each type of hydrogel dressing will provide insights into the future design of antimicrobial hydrogels for better management of wounds in clinical application

An implantable nano-enabled bio-robotic intracranial device for targeted and prolonged drug delivery

A thesis submitted to the Faculty of Health Sciences, University of the Witwatersrand, in fulfillment of the requirements for the degree of Doctor of PhilosophyAlzheimer’s disease (AD) is the most prevalent and progressive neurodegenerative disorder (ND). It is characterized by a progressive decline of cognitive function, complete loss of memory, deterioration of visual capacity and the inability to function independently. According to the World Health Organization (WHO) it is estimated that about 26 million people suffer with AD worldwide. Although the etiology of AD is not fully understood, the aggregation of β-amyloidal (A) peptides that are associated with the formation of extracellular neurotoxin senile plaques and neurofibrillary tangles comprising hyperphosphorylated tau proteins have been recognized as the primary constituents that play a crucial role in AD. Several potential neurotherapeutic agents that can improve the management of AD such as metal chelators and alkaloid drugs have been approved by the US Food and Drug Administration (FDA) and European Medicines Agency (EMA). Metal chelators [e.g. histidine, Ethylenediaminetetraacetic acid (EDTA) and zinc acetate (ZnAc)] are the main therapy used for modulating Aβ peptide aggregation with biological metals (such as zinc and copper ions) which is associated with promoting neurotoxicity in AD. While alkaloid drugs, such as donepezil, galantamine and rivastigmine, are used to inhibit the enzyme acetylcholinesterase (AChE); memantine is used to block the N-methyl-D-aspartate (NMDA) receptors associated with pathological activation. Despite the availability of these indispensable drugs, the clinical utility of these drugs is hampered by their poor retention and difficulty in bypassing the highly restrictive Blood Brain Barrier (BBB). Therefore this study aimed at developing novel nanoliposomes (NLPs) surface-engineered with chelating and synthetic peptides that are capable of crossing the BBB thus improving delivery efficacy and modulating the extracellular neurotoxicity associated with β-Amyloid aggregates of AD. Furthermore, since this system was designed for a chronic condition, a temporary depot-based polymeric system was integrated for further enhancement of the liposomal half-life, storage and prolonged drug delivery over a period of 50 days. The surface-engineered NLPs produced were spherical in shape, 100-149±28nm ~ size, with a zeta potential range of -9.59 to -37.3mV and a polydispersity index (PdI) of 0.02-0.2. A Box-Behnken experimental design was employed for maximizing the ligand coupling efficiency (40-78%) and drug entrapment efficiency (DEE) that ranged from 42-79%. The optimized peptide-based ligand NLP formulation showed sustained drug release (30% of drug released within 48 hours). Chelating ligands on the surface of NLPs showed 50-68% modulation of neurotoxicity on PC12 neuronal cells induced by ZnAβ (1-42) or CuAβ (1-42) aggregates. When drug-loaded functionalized NLPs were embedded within the temporal hydrophilic hydrogel network/scaffold as an implantable nano-enabled bio-robotic intracranial device (BICD), the physicomechanical and physicochemical dynamics showed improvement of liposomal structure such as the stability, and homogeneity in distribution of the liposomes within the internal core of the hydrogel networks and post-lyophilized scaffold. In vitro studies in simulated cerebrospinal fluid (CSF) showed prolonged release behavior of the drug-loaded functionalized NLPs from the BICD with 50-70% released over 50 days. Scanning Electron Microscopy (SEM) and confocal microscopy confirmed intact liposomal structures within the temporal polymeric scaffold/depot post-fixation and post-lyophilization. Ex vivo studies confirmed cell proliferation and a low level of lactate dehydrogenase (LDH), which is associated with cell membrane damage/injury, after PC12 neuronal cells were exposed to the BICD. In addition, when PC12 neuronal cells were exposed to the BICD high accumulation of galantamine (GAL) into these PC12 neuronal cells was observed post-cultivation. This outcome indicated that the released drug-loaded functionalized NLPs from the BICD were still in their intact form and capable of serving as bio-robotic markers for the delivery of GAL into the neuronal cells in response to AD. Furthermore, intracellular activity validated that the synthetic peptide has the potency for targeted delivery of the drug-loaded NLPs post-release of the BICD in ex vivo studies. Overall, results from this study revealed that the BICD device had superior cytocompatibility and may be suitable for application as a prolonged and targeted delivery system for GAL into neuronal cells to treat AD

Smart Hydrogels Meet Carbon Nanomaterials for New Frontiers in Medicine

Carbon nanomaterials include diverse structures and morphologies, such as fullerenes, nano-onions, nanodots, nanodiamonds, nanohorns, nanotubes, and graphene-based materials. They have attracted great interest in medicine for their high innovative potential, owing to their unique electronic and mechanical properties. In this review, we describe the most recent advancements in their inclusion in hydrogels to yield smart systems that can respond to a variety of stimuli. In particular, we focus on graphene and carbon nanotubes, for applications that span from sensing and wearable electronics to drug delivery and tissue engineering

Water-Soluble and Insoluble Polymers and Biopolymers for Biomedical, Environmental, and Biological Applications

The use of polymers in biological applications is defined by the interactions promoted between living organisms and polymeric chains, which are generally associated with the polymers’ hydrophilic and hydrophobic behaviors. However, these water-friendly structures are also very useful for other applications, such as the adsorption of pollutants from sewage water. The modulation of the final properties of water-soluble and insoluble polymers tends to define the spectra of features associated with their final applications

Amphoteric Soy Protein-Rich Fibers for Rapid and Selective Adsorption and Desorption of Ionic Dyes.

Uniquely amphoteric soy protein (SP)-rich ultra-fine fibers (231 nm average diameter) have been facilely electrospun from aq. colloids and rendered water-insoluble by heating (150 °C, 12 h) to be highly stable over 14 d (pH 7) as well as under extremely acidic to basic (pH 0-10, 2 d) or at boil (2 h) conditions. The SP-rich fibrous membranes are easily tuned to be charged either negatively by deprotonation above or positively by protonation below the 4.5 PI of SPs. This pH-responsive amphoterism has been demonstrated for rapid adsorption of either cationic or anionic dyes, selective adsorption of either dye from their mixtures, and repetitive adsorption/desorption to recover and reuse both dyes and membranes. Chemisorption and heterogeneous adsorption of ionic dyes was confirmed by close fitting to the pseudo-second-order kinetic model (R 2 = 0.9977-0.9999) and Freundlich adsorption isotherm (R 2 = 0.9879). This is the first report of water-resilient and pH-robust ultrafine fibrous membranes fabricated from aqueous colloids of neat globular SPs, the major byproducts of under-utilized edible oil and biodiesel. The natural polyampholyte origin, amphoterism, and green processing make these fibrous materials unique and versatile for many potential applications involving both anionic and cationic species

Nanocellulose and Nanocarbons Based Hybrid Materials

This highly informative and carefully presented book discusses the preparation, processing, characterization and applications of different types of hybrid nanomaterials based on nanocellulose and/or nanocarbons. It gives an overview of recent advances of outstanding classes of hybrid materials applied in the fields of physics, chemistry, biology, medicine, and materials science, among others. The content of this book is relevant to researchers in academia and industry professionals working on the development of advanced hybrid nanomaterials and their applications

Advances in Hydrogels

Hydrogels are a class of soft materials with crosslinked network structures. They show good biocompatibility, biodegradability, hydrophilicity, and mechanical properties similar to those of tissue, so they have a wide range of applications. In recent years, a variety of multifunctional hydrogels with excellent performance have been developed, greatly expanding the depth and breadth of their applications. This book is the reprint of the Special Issue “Advances in Hydrogels”, which focused on the recent advances regarding hydrogels, aiming to provide reference for researchers in related fields. This book included one editorial, thirteen original research articles, and three valuable reviews from thirteen different countries including Canada, China, Thailand, Mexico, India, Saudi Arabia, Chile, Germany, the Czech Republic, Colombia, Romania, Israel, and the USA

Development of Biomaterials for Drug Delivery

Drug delivery systems (DDS) have highly evolved in the last decades with the development of hydrogels and nanoparticles. However, high systemic uptake, side effects, low bioavailability, and encapsulation efficiency continue to be a major hurdle faced by such DDSs. Nanoparticles and hydrogels can be specifically designed for targeted DDSs to mitigate some of the problems. This dissertation aimed to design two DDSs for ocular drug delivery and one for cancer treatment. The first project sought to develop chitosan nanoparticles (Cs-NP) using PEGDA as a copolymer to encapsulate gentamicin (GtS) for ocular drug delivery. Cs-NPs contain positive charges that can interact with negatively charged ocular proteins to increase the NP residence time. Simultaneously, ocular enzymes degrade the chitosan β-(1→4)-glycosidic bonds to release GtS at the eye\u27s surface, therefore, preventing premature release of GtS. PEGDA was used to increase drug encapsulation by shielding the repelling forces of like charges between Cs and GtS. The data shows PEGDA does not hinder enzymatic degradation while increasing drug encapsulation efficiency and producing more stable and homogeneous particles. The second project utilized Michael\u27s reaction to crosslink Cs, Cs-NPs, and PEGDA to produce a film designed for ocular drug delivery. The film serves as an anchor for the NPs to prevent drug removal by tears and blinking. The data shows that crosslinking of Cs and PEGDA does not affect lysozyme activity, and NPs could successfully release GtS without affecting GtS activity. Finally, the third project sought to compare the cytotoxicity of the polysaccharide fucoidan (FU) encapsulated into chitosan nanoparticles (CFU) and without encapsulation (free-FU) and their effects on two cancer cell lines. The results indicate that free-FU has very little toxicity to MDA-MB-231 cancer cells compared to MCF-7. However, cytotoxicity to MDA-MB-231 cells was increased by delivering encapsulated FU. Free-FU can enter MCF-7 cells using surface receptors that are not present in MDA-MB-231 cells. Therefore, by encapsulating FU into Cs-NPs, cytotoxicity can be increased as Cs-NPs containing FU are endocytosed into the MDA-MB-231 cells

Electrospun Composite Nanofibers for Functional Applications

This reprint includes research articles on various applications of electrospun nanofibers. Nanofibers have potential to be used in tissue engineering, energy harvesting, sensors, separators, water filtration, air filtration, and other applications as well. This Special Issue has received 11 interesting research articles, which covers such application areas

Recent Progress in Photoresponsive Biomaterials

: Photoresponsive biomaterials have garnered increasing attention recently due to their ability to dynamically regulate biological interactions and cellular behaviors in response to light. This review provides an overview of recent advances in the design, synthesis, and applications of photoresponsive biomaterials, including photochromic molecules, photocleavable linkers, and photoreactive polymers. We highlight the various approaches used to control the photoresponsive behavior of these materials, including modulation of light intensity, wavelength, and duration. Additionally, we discuss the applications of photoresponsive biomaterials in various fields, including drug delivery, tissue engineering, biosensing, and optical storage. A selection of significant cutting-edge articles collected in recent years has been discussed based on the structural pattern and light-responsive performance, focusing mainly on the photoactivity of azobenzene, hydrazone, diarylethenes, and spiropyrans, and the design of smart materials as the most targeted and desirable application. Overall, this review highlights the potential of photoresponsive biomaterials to enable spatiotemporal control of biological processes and opens up exciting opportunities for developing advanced biomaterials with enhanced functionality