Swelling/deswelling, thermal, and rheological behavior of PVA-g-NIPAAm nanohydrogels prepared by a facile free-radical polymerization method

Green synthesis of quince/pectin cross-linked superporous hydrogel sponges for pH-regulated sustained domperidone delivery

The present study aims to utilize green synthesis to fabricate stimuli-responsive, smart, quince/pectin cross-linked hydrogel sponges for the pH-regulated conveyance of domperidone. The designed hydrogel sponges were evaluated for a sol-gel fraction (%), swelling studies and kinetics, drug loading (%), electrolyte-responsive character, scanning electron microscopy (SEM), thermal analysis, drug-excipient compatibility studies (FTIR), X-ray diffraction (XRD) analysis, mechanical testing, in-vitro drug release studies, and acute oral toxicity studies. The drug loading (%) ranged from 67 to 85%. Hydrogel sponges displayed pH-responsive swelling potential, with optimum swelling in a phosphate buffer (pH 7.4) and insignificant swelling in an acidic buffer of pH 1.2. The prepared hydrogel sponges displayed second-order swelling dynamics. The FTIR data revealed the successful fabrication of the hydrogel sponges with the primary drug peaks remaining unchanged, demonstrating excipients-drug compatibility. SEM confirmed the rough, porous surface of hydrogel sponges with numerous cracks. XRD measurements revealed the transformation of the crystalline nature of domperidone into an amorphous one within the developed hydrogel sponges. Dissolution studies revealed little domperidone release in an acidic environment. However, hydrogel sponges exhibited release up to 10 h in phosphate buffer.The sponge's non-toxic or biocompatible character was confirmed through toxicological studies. Thus, the finding indicates that quince/pectin cross-linked hydrogel sponges are durable enough to deliver the domperidone to the gut for a longer time.

Preparation and Characterization of Temperature/pH Dual-Responsive Gel Spheres for Immobilizing Nitro Bacteria

The temperature/pH dual-responsive gel spheres were prepared by orthogonal experiments and response surface methodology, and finally, the optimal synthesis conditions were obtained by a composite score, including swelling, mechanical properties, mass transfer properties, and so forth. The results showed that a sodium alginate concentration of 3% (w/v), CaCl₂ concentration of 2% (w/v), gelling time of 40 h, drop height of 14 cm, NaCl concentration of 0.6% (w/v), N-isopropylacrylamide concentration of 0.03% (w/v), and acrylic acid concentration of 4.06% (w/v) were optimal synthesis conditions. The environmental change tolerance experiments showed that the nitrogen removal of the dual-response nitrifying gel spheres was better than the domesticated sludge at low temperatures (4 °C) and in alkaline (pH 9 and 10) conditions. The as-obtained gel spheres can respond intelligently to the changes in ambient temperature and pH. It is hoped that this study will provide technical parameters for the development and application of microbial immobilization carriers.

Dually Cross-Linked Core-Shell Structure Nanohydrogel with Redox-Responsive Degradability for Intracellular Delivery

A redox-responsive nanocarrier is a promising strategy for the intracellular drug release because it protects the payload, prevents its undesirable leakage during extracellular transport, and favors site-specific drug delivery. In this study, we developed a novel redox responsive core-shell structure nanohydrogel prepared by a water in oil nanoemulsion method using two biocompatible synthetic polymers: vinyl sulfonated poly(N-(2-hydroxypropyl) methacrylamide mono/dilactate)-polyethylene glycol-poly(N-(2-hydroxypropyl) methacrylamide mono/dilactate) triblock copolymer, and thiolated hyaluronic acid. The influence on the nanohydrogel particle size and distribution of formulation parameters was investigated by a three-level full factorial design to optimize the preparation conditions. The surface and core-shell morphology of the nanohydrogel were observed by scanning electron microscope, transmission electron microscopy, and further confirmed by Fourier transform infrared spectroscopy and Raman spectroscopy from the standpoint of chemical composition. The redox-responsive biodegradability of the nanohydrogel in reducing environments was determined using glutathione as reducing agent. A nanohydrogel with particle size around 250 nm and polydispersity index around 0.1 is characterized by a thermosensitive shell which jellifies at body temperature and crosslinks at the interface of a redox-responsive hyaluronic acid core via the Michael addition reaction. The nanohydrogel showed good encapsulation efficiency for model macromolecules of different molecular weight (93% for cytochrome C, 47% for horseradish peroxidase, and 90% for bovine serum albumin), capacity to retain the peroxidase-like enzymatic activity (around 90%) of cytochrome C and horseradish peroxidase, and specific redox-responsive release behavior. Additionally, the nanohydrogel exhibited excellent cytocompatibility and internalization efficiency into macrophages. Therefore, the developed core-shell structure nanohydrogel can be considered a promising tool for the potential intracellular delivery of different pharmaceutical applications, including for cancer therapy.

Dual Crosslinked Collagen/Chitosan Film for Potential Biomedical Applications

The application of polymeric biomaterial scaffolds utilizing crosslinking strategy has become an effective approach in these days. In the present study, the development and characterization of collagen-chitosan hydrogel film has been reported on using dual crosslinking agent's, i.e., tannic acid and genipin simultaneously. Incorporation of genipin imparts a greenish-blue color to the polymeric film. The effect of dual crosslinking and their successful interaction within the matrix was evaluated by infrared analysis spectroscopy. The porosity of the film was examined using scanning electron microscopy (SEM). Results of TGA determine the intermediate thermal degradation. Further, the crosslinking phenomenon has found primary impact on the strength of the films. Enzymatic degradation for the films was performed with lysozyme and lipase. The cell adhesion and proliferation was also accomplished using mouse embryonic cell lines wherein the cells cultured on the dual crosslinked film. The thriving utilization of such dual crosslinked polymeric film finds their applications in ophthalmology especially as an implant for temporary injured cornea and skin tissue regeneration.

Dual thermo-and pH-sensitive injectable hydrogels of chitosan/(poly(N-isopropylacrylamide-co-itaconic acid)) for doxorubicin delivery in breast cancer

In this work, dual thermo- and pH-responsive hydrogels were developed and loaded with doxorubicin (DOX) with potential therapy of breast cancer. Hydrogels were engineered by blending synthesized poly(N-isopropylacrylamide-co-itaconic acid) (PNIAAm-co-IA) with chitosan (CS) through ionic crosslinking using glycerophosphate (GP). The synthesized copolymer and hydrogels were characterized by means of various techniques such as FT-IR, ¹H NMR, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). Lower critical solution temperature (LCST) of the copolymer was determined around 39 °C using UV-Vis spectroscopy. Swelling studies of hydrogels and their morphology implied the porous structure, high water content with rapid swelling/deswelling rate in response to abrupt changes of pH and temperature. The release investigation of DOX at different concentration, temperature and pH values confirmed the accelerated release of DOX in lower concentration and acidic condition at 37 °C as compared to neutral pH and the temperature of 40 °C. The MTT cytotoxicity study revealed that the hydrogels are cytocompatible and exert no/negligible cytotoxicity on MCF-7 cells. The proliferation of MCF-7 cells on the prepared hydrogel and DOX-loaded hydrogel was evaluated by 4',6-diamidino-2-phenylindole (DAPI) staining which further demonstrated the potential of developed hydrogels for local therapy of breast cancer.

Nanomedicine and advanced technologies for burns: Preventing infection and facilitating wound healing

According to the latest report from the World Health Organization, an estimated 265,000 deaths still occur every year as a direct result of burn injuries. A widespread range of these deaths induced by burn wound happens in low- and middle-income countries, where survivors face a lifetime of morbidity. Most of the deaths occur due to infections when a high percentage of the external regions of the body area is affected. Microbial nutrient availability, skin barrier disruption, and vascular supply destruction in burn injuries as well as systemic immunosuppression are important parameters that cause burns to be susceptible to infections. Topical antimicrobials and dressings are generally employed to inhibit burn infections followed by a burn wound therapy, because systemic antibiotics have problems in reaching the infected site, coupled with increasing microbial drug resistance. Nanotechnology has provided a range of molecular designed nanostructures (NS) that can be used in both therapeutic and diagnostic applications in burns. These NSs can be divided into organic and non-organic (such as polymeric nanoparticles (NPs) and silver NPs, respectively), and many have been designed to display multifunctional activity. The present review covers the physiology of skin, burn classification, burn wound pathogenesis, animal models of burn wound infection, and various topical therapeutic approaches designed to combat infection and stimulate healing. These include biological based approaches (e.g. immune-based antimicrobial molecules, therapeutic microorganisms, antimicrobial agents, etc.), antimicrobial photo- and ultrasound-therapy, as well as nanotechnology-based wound healing approaches as a revolutionizing area. Thus, we focus on organic and non-organic NSs designed to deliver growth factors to burned skin, and scaffolds, dressings, etc. for exogenous stem cells to aid skin regeneration. Eventually, recent breakthroughs and technologies with substantial potentials in tissue regeneration and skin wound therapy (that are as the basis of burn wound therapies) are briefly taken into consideration including 3D-printing, cell-imprinted substrates, nano-architectured surfaces, and novel gene-editing tools such as CRISPR-Cas.

Legionella Pneumophila and Dendrimers-Mediated Antisense Therapy

Finding novel and effective antibiotics for treatment of Legionella disease is a challenging field. Treatment with antibiotics usually cures Legionella infection; however, if the resultant disease is not timely recognized and treated properly, it leads to poor prognosis and high case fatality rate. Legionella pneumophila DrrA protein (Defects in Rab1 recruitment protein A)/also known as SidM affects host cell vesicular trafficking through modification of the activity of cellular small guanosine triphosphatase )GTPase( Rab (Ras-related in brain) function which facilitates intracellular bacterial replication within a supporter vacuole. Also, Legionella pneumophila LepA and LepB (Legionella effector protein A and B) proteins suppress host-cell Rab1 protein's function resulting in the cell lysis and release of bacteria that subsequently infect neighbour cells. Legionella readily develops resistant to antibiotics and, therefore, new drugs with different modes of action and therapeutic strategic approaches are urgently required among antimicrobial drug therapies;gene therapy is a novel approach for Legionnaires disease treatment. On the contrary to the conventional treatment approaches that target bacterial proteins, new treatment interventions target DNA (Deoxyribonucleic acid), RNA (Ribonucleic acid) species, and different protein families or macromolecular complexes of these components. The above approaches can overcome the problems in therapy of Legionella infections caused by antibiotics resistance pathogens. Targeting Legionella genes involved in manipulating cellular vesicular trafficking using a dendrimer-mediated antisense therapy is a promising approach to inhibit bacterial replication within the target cells.

Smart Nanostructures for Cargo Delivery: Uncaging and Activating by Light

Nanotechnology has begun to play a remarkable role in various fields of science and technology. In biomedical applications, nanoparticles have opened new horizons, especially for biosensing, targeted delivery of therapeutics, and so forth. Among drug delivery systems (DDSs), smart nanocarriers that respond to specific stimuli in their environment represent a growing field. Nanoplatforms that can be activated by an external application of light can be used for a wide variety of photoactivated therapies, especially light-triggered DDSs, relying on photoisomerization, photo-cross-linking/un-cross-linking, photoreduction, and so forth. In addition, light activation has potential in photodynamic therapy, photothermal therapy, radiotherapy, protected delivery of bioactive moieties, anticancer drug delivery systems, and theranostics (i.e., real-time monitoring and tracking combined with a therapeutic action to different diseases sites and organs). Combinations of these approaches can lead to enhanced and synergistic therapies, employing light as a trigger or for activation. Nonlinear light absorption mechanisms such as two-photon absorption and photon upconversion have been employed in the design of light-responsive DDSs. The integration of a light stimulus into dual/multiresponsive nanocarriers can provide spatiotemporal controlled delivery and release of therapeutic agents, targeted and controlled nanosystems, combined delivery of two or more agents, their on-demand release under specific conditions, and so forth. Overall, light-activated nanomedicines and DDSs are expected to provide more effective therapies against serious diseases such as cancers, inflammation, infections, and cardiovascular disease with reduced side effects and will open new doors toward the treatment of patients worldwide.

Hydrogels for ocular drug delivery and tissue engineering

Hydrogels, as crosslinked polymeric three dimensional networks, possess unique structure and behavior in response to the internal and/or external stimuli. As a result, they offer great prospective applications in drug delivery, cell therapy and human tissue engineering. Here, we highlight the potential of hydrogels in prolonged intraocular drug delivery and ocular surface therapy using stem cells incorporated hydrogels.

Influence of temperature, pH and simulated biological solutions on swelling and structural properties of biomineralized (CaCO3) PVP-CMC hydrogel

Abstract

Biomaterials having stimuli response are interesting in the biomedical field. This paper reports about swelling response and internalstructural of biomineralized (CaCO₃) polyvinylpyrrolidone (PVP) carboxymethylcellulose (CMC) hydrogel having various thicknesses (0.1–0.4 mm). Samples were tested in aqueous solution using temperature ranges from 10 to 40 °C; pH varies from 4 to 9, time 60 min. In addition, an experiment was conducted in the presence of simulated biological solutions (SBS): glucose (GS), physiological fluid (PS) and urea (US) at temperature 37 °C and pH 7.5 for 180 min. It is noticed that the maximum swelling ratio reached in 30–40 °C at pH 7 in aqueous solution. Among biological fluids, the swelling ratio shows: US > PS > GS at temperature 37 °C, pH 7.5, time 150 min. The equilibrium swelling ratio of the test sample in SBS and their non-reformative apparent structure confirm that biomineralized (CaCO₃) PVP–CMC hydrogel can be acclaimed for medical application like bone tissue engineering.

Graphical Abstract