Thermo-sensitive gellan maleate/N-isopropylacrylamide hydrogels: initial “in vitro” and “in vivo” evaluation as ocular inserts

Evaluating the Efficacy of a Thermoresponsive Hydrogel for Delivering Anti-Collagen Antibodies to Reduce Posttraumatic Scarring in Orthopedic Tissues

Excessive posttraumatic scarring in orthopedic tissues, such as joint capsules, ligaments, tendons, muscles, and peripheral nerves, presents a significant medical problem, resulting in pain, restricted joint mobility, and impaired musculoskeletal function. Current treatments for excessive scarring are often ineffective and require the surgical removal of fibrotic tissue, which can aggravate the problem. The primary component of orthopedic scars is collagen I-rich fibrils. Our research team has developed a monoclonal anti-collagen antibody (ACA) that alleviates posttraumatic scarring by inhibiting collagen fibril formation. We previously established the safety and efficacy of ACA in a rabbit-based arthrofibrosis model. In this study, we evaluate the utility of a well-characterized thermoresponsive hydrogel (THG) as a delivery vehicle for ACA to injury sites. Crucial components of the hydrogel included N-isopropylacrylamide, poly(ethylene glycol) diacrylate, and hyaluronic acid. Our investigation focused on in vitro ACA release kinetics, stability, and activity. Additionally, we examined the antigen-binding characteristics of ACA post-release from the THG in an in vivo context. Our preliminary findings suggest that the THG construct exhibits promise as a delivery platform for antibody-based therapeutics to reduce excessive scarring in orthopedic tissues.

Stimuli-responsive hydrogels: smart state of-the-art platforms for cardiac tissue engineering

Biomedicine and tissue regeneration have made significant advancements recently, positively affecting the whole healthcare spectrum. This opened the way for them to develop their applications for revitalizing damaged tissues. Thus, their functionality will be restored. Cardiac tissue engineering (CTE) using curative procedures that combine biomolecules, biomimetic scaffolds, and cells plays a critical part in this path. Stimuli-responsive hydrogels (SRHs) are excellent three-dimensional (3D) biomaterials for tissue engineering (TE) and various biomedical applications. They can mimic the intrinsic tissues' physicochemical, mechanical, and biological characteristics in a variety of ways. They also provide for 3D setup, adequate aqueous conditions, and the mechanical consistency required for cell development. Furthermore, they function as competent delivery platforms for various biomolecules. Many natural and synthetic polymers were used to fabricate these intelligent platforms with innovative enhanced features and specialized capabilities that are appropriate for CTE applications. In the present review, different strategies employed for CTE were outlined. The light was shed on the limitations of the use of conventional hydrogels in CTE. Moreover, diverse types of SRHs, their characteristics, assembly and exploitation for CTE were discussed. To summarize, recent development in the construction of SRHs increases their potential to operate as intelligent, sophisticated systems in the reconstruction of degenerated cardiac tissues.

In-Situ Thermoresponsive Hydrogel Containing Resveratrol-Loaded Nanoparticles as a Localized Drug Delivery Platform for Dry Eye Disease

Dry eye disease (DED) is a dynamic and complex disease that can cause significant damage to the ocular surface and discomfort, compromising the patient's quality of life. Phytochemicals such as resveratrol have received increasing attention due to their ability to interfere with multiple pathways related to these diseases. However, the low bioavailability and the poor therapeutic response of resveratrol hinder its clinical applications. Cationic polymeric nanoparticles, in combination with in situ gelling polymers, could represent a promising strategy to prolong drug corneal residence time reducing the frequency of administration and increasing the therapeutic response. Eyedrop formulations, based on acetylated polyethyleneimine-modified polylactic-co-glicolyc acid- (PLGA-PEI) nanoparticles loaded with resveratrol (RSV-NPs) were dispersed into poloxamer 407 hydrogel and characterized in terms of pH, gelation time, rheological properties, in vitro drugs release, and biocompatibility. Moreover, the antioxidant and anti-inflammatory effects of RSV were assessed in vitro by mimicking a DED condition through the exposition of epithelial corneal cells to a hyperosmotic state. This formulation exhibited sustained release of RSV for up to 3 days, exerting potent antioxidant and anti-inflammatory effects on corneal epithelial cells. In addition, RSV reversed the mitochondrial dysfunction mediated by high osmotic pressure, leading to upregulated sirtuin-1 (SIRT1) expression, an essential regulator of mitochondrial function. These results suggest the potential of eyedrop formulation as a platform to overcome the rapid clearance of current solutions for treating various inflammation- and oxidative stress-related diseases such as DED.

A Review on Biomedical Application of Polysaccharide-Based Hydrogels with a Focus on Drug Delivery Systems

Over the last years of research on drug delivery systems (DDSs), natural polymer-based hydrogels have shown many scientific advances due to their intrinsic properties and a wide variety of potential applications. While drug efficacy and cytotoxicity play a key role, adopting a proper DDS is crucial to preserve the drug along the route of administration and possess desired therapeutic effect at the targeted site. Thus, drug delivery technology can be used to overcome the difficulties of maintaining drugs at a physiologically related serum concentration for prolonged periods. Due to their outstanding biocompatibility, polysaccharides have been thoroughly researched as a biological material for DDS advancement. To formulate a modified DDS, polysaccharides can cross-link with different molecules, resulting in hydrogels. According to our recent findings, targeted drug delivery at a certain spot occurs due to external stimulation such as temperature, pH, glucose, or light. As an adjustable biomedical device, the hydrogel has tremendous potential for nanotech applications in involved health areas such as pharmaceutical and biomedical engineering. An overview of hydrogel characteristics and functionalities is provided in this review. We focus on discussing the various kinds of hydrogel-based systems on their potential for effectively delivering drugs that are made of polysaccharides.

Mechanoresponsive Drug Loading System with Tunable Host-Guest Interactions for Ocular Disease Treatment

Conventional administration of eye drops often requires high dosages and/or repetitive treatments to achieve therapeutic efficacy. This is inefficient and may result in side effects or even toxicity. Although many delivery systems of ophthalmic drugs have been reported, most of them work in a fixed format in which both the type and dose of the loaded drugs cannot be changed upon demand. To overcome this limitation, a hybrid double network hydrogel system composed of methacryloyl gelatin, pluronic F127 diacrylate, and β-cyclodextrin-modified oxidized dextran was developed. The hydrogels presented good mechanical strength and biocompatibility. In vitro assessments demonstrated that the hydrogels loaded with commonly used ophthalmic drugs could sustain the drug release for more than 21 days. This hydrogel system exhibited features of mechanoresponsive drug loading, and the capacity of drug loading could be significantly enhanced by macroscopically mechanical compression. Further in vivo evaluation of the drug delivery capacity showed that a dexamethasone-loaded hydrogel as a fornix insert effectively suppressed upregulation of proangiogenic factors and suture-induced corneal neovascularization in rats. This novel hydrogel system represents a promising drug delivery platform, which could potentially improve the treatments of ocular surface and other diseases.

Smart/stimuli-responsive hydrogels: Cutting-edge platforms for tissue engineering and other biomedical applications

Recently, biomedicine and tissue regeneration have emerged as great advances that impacted the spectrum of healthcare. This left the door open for further improvement of their applications to revitalize the impaired tissues. Hence, restoring their functions. The implementation of therapeutic protocols that merge biomimetic scaffolds, bioactive molecules, and cells plays a pivotal role in this track. Smart/stimuli-responsive hydrogels are remarkable three-dimensional (3D) bioscaffolds intended for tissue engineering and other biomedical purposes. They can simulate the physicochemical, mechanical, and biological characters of the innate tissues. Also, they provide the aqueous conditions for cell growth, support 3D conformation, provide mechanical stability for the cells, and serve as potent delivery matrices for bioactive molecules. Many natural and artificial polymers were broadly utilized to design these intelligent platforms with novel advanced characteristics and tailored functionalities that fit such applications. In the present review, we highlighted the different types of smart/stimuli-responsive hydrogels with emphasis on their synthesis scheme. Besides, the mechanisms of their responsiveness to different stimuli were elaborated. Their potential for tissue engineering applications was discussed. Furthermore, their exploitation in other biomedical applications as targeted drug delivery, smart biosensors, actuators, 3D and 4D printing, and 3D cell culture were outlined. In addition, we threw light on smart self-healing hydrogels and their applications in biomedicine. Eventually, we presented their future perceptions in biomedical and tissue regeneration applications. Conclusively, current progress in the design of smart/stimuli-responsive hydrogels enhances their prospective to function as intelligent, and sophisticated systems in different biomedical applications.

Recent Advances in the Excipients Used for Modified Ocular Drug Delivery

In ocular drug delivery, maintaining an efficient concentration of the drug in the target area for a sufficient period of time is a challenging task. There is a pressing need for the development of effective strategies for drug delivery to the eye using recent advances in material sciences and novel approaches to drug delivery. This review summarizes the important aspects of ocular drug delivery and the factors affecting drug absorption in the eye including encapsulating excipients (chitosan, hyaluronic acid, poloxamer, PLGA, PVCL-PVA-PEG, cetalkonium chloride, and gelatin) for modified drug delivery.

Chitosan Derivatives with Mucoadhesive and Antimicrobial Properties for Simultaneous Nanoencapsulation and Extended Ocular Release Formulations of Dexamethasone and Chloramphenicol Drugs

The aim of this work was to evaluate the effectiveness of neat chitosan (CS) and its derivatives with 2-acrylamido-2-methyl-1-propanesulfonic acid (AAMPS) and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (MEDSP) as appropriate nanocarriers for the simultaneous ocular administration of dexamethasone sodium phosphate (DxP) and chloramphenicol (CHL). The derivatives CS-AAMPS and CS-MEDSP have been synthesized by free-radical polymerization and their structure has been proved by Fourier-Transformed Infrared Spectroscopy (FT-IR) spectroscopy. Both derivatives exhibited low cytotoxicity, enhanced mucoadhesive properties and antimicrobial activity against Staphylococcus aureus (S.aureus) and Escherichia coli (E. coli). Encapsulation was performed via ionic crosslinking gelation using sodium tripolyphosphate (TPP) as the crosslinking agent. Dynamic light scattering measurements (DLS) showed that the prepared nanoparticles had bimodal distribution and sizes ranging from 50–200 nm and 300–800 nm. Drugs were encapsulated in their crystalline (CHL) or amorphous (DexSP) form inside nanoparticles and their release rate was dependent on the used polymer. The CHL dissolution rate was substantially enhanced compared to the neat drug and the release time was extended up to 7 days. The release rate of DexSP was much faster than that of CHL and was prolonged up to 3 days. Drug release modeling unveiled that diffusion is the main release mechanism for both drugs. Both prepared derivatives and their drug-loaded nanoparticles could be used for extended and simultaneous ocular release formulations of DexSP and CHL drugs.

Therapies Based on Nanoparticles for Eye Drug Delivery

Eye drug delivery, particularly to the retina, is a technical hurdle that needs to be solved and represents an ongoing current important medical field. Posterior segment eye diseases are a major cause of visual impairment worldwide. Age-related macular degeneration, glaucoma, and diabetic retinopathy are the major causes of blindness. To achieve efficient drug delivery and drug retention time in the posterior segment of the eye, novel delivery systems based on nanoparticles have been developed in the last few years. Nowadays, liposomes represent the most utilized nanoparticles for eye drug delivery and, recently, a broad spectrum of diverse nanoparticles continue to emerge with special characteristics representing ideal candidates for eye drug 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.).

Hydrogel Biomaterials for Application in Ocular Drug Delivery

There are many challenges involved in ocular drug delivery. These are a result of the many tissue barriers and defense mechanisms that are present with the eye; such as the cornea, conjunctiva, the blinking reflex, and nasolacrimal drainage system. This leads to many of the conventional ophthalmic preparations, such as eye drops, having low bioavailability profiles, rapid removal from the administration site, and thus ineffective delivery of drugs. Hydrogels have been investigated as a delivery system which is able to overcome some of these challenges. These have been formulated as standalone systems or with the incorporation of other technologies such as nanoparticles. Hydrogels are able to be formulated in such a way that they are able to change from a liquid to gel as a response to a stimulus; known as "smart" or stimuli-responsive biotechnology platforms. Various different stimuli-responsive hydrogel systems are discussed in this article. Hydrogel drug delivery systems are able to be formulated from both synthetic and natural polymers, known as biopolymers. This review focuses on the formulations which incorporate biopolymers. These polymers have a number of benefits such as the fact that they are biodegradable, biocompatible, and non-cytotoxic. The biocompatibility of the polymers is essential for ocular drug delivery systems because the eye is an extremely sensitive organ which is known as an immune privileged site.