Design and evaluation of pH-responsive hydrogel for oral delivery of amifostine and study on its radioprotective effects

Progress in Designing Therapeutic Antimicrobial Hydrogels Targeting Implant-associated Infections: Paving the Way for a Sustainable Platform Applied to Biomedical Devices

Implantable biomedical devices have found widespread use in restoring lost functions or structures within the human body, but they face a significant challenge from microbial-related infections, which often lead to implant failure. In this context, antimicrobial hydrogels emerge as a promising strategy for treating implant-associated infections owing to their tunable physicochemical properties. However, the literature lacks a comprehensive analysis of antimicrobial hydrogels, encompassing their development, mechanisms, and effect on implant-associated infections, mainly in light of existing in vitro, in vivo, and clinical evidence. Thus, this review addresses the strategies employed by existing studies to tailor hydrogel properties to meet the specific needs of each application. Furthermore, this comprehensive review critically appraises the development of antimicrobial hydrogels, with a particular focus on solving infections related to metallic orthopedic or dental implants. Then, preclinical and clinical studies centering on providing quantitative microbiological results associated with the application of antimicrobial hydrogels are systematically summarized. Overall, antimicrobial hydrogels benefit from the tunable properties of polymers and hold promise as an effective strategy for the local treatment of implant-associated infections. However, future clinical investigations, grounded on robust evidence from in vitro and preclinical studies, are required to explore and validate new antimicrobial hydrogels for clinical use.

Dual-targeting galactose-functionalized hyaluronic acid modified lipid nanoparticles delivering silybin for alleviating alcoholic liver injury

Alcoholic liver injury stands as a predominant pathogenic contributor to the global burden of liver diseases, with alcohol consumption serving as a significant determinant of worldwide morbidity and mortality. Given that liver-targeted therapy for mitigating alcoholic liver injury remains to be a major clinical challenge due to the poor specificity and instability associated with single targeting modification in actively targeted nanomedicine systems, bifunctional targeting modification may serve as a more promising strategy. Here, galactose-functionalized hyaluronic acid (Gal-HA) coated cationic solid lipid nanoparticles carrying silybin (Gal-HA/SIL-SLNPs) featuring dual-targeting hyaluronic acid (HA) and galactose (Gal) moieties, enabled specific liver surface targeting of asialoglycoprotein receptor (ASGPR) and cluster of differentiation 44 (CD44) proteins to enhance silybin uptake, while simultaneously ameliorating the deficiencies of positively charged lipid nanoparticles as drug carriers and preserving their stability in the bloodstream. Based on the findings, Gal-HA/SIL-SLNPs with excellent biocompatibility demonstrated improved cellular internalization and liver distribution, while also displaying ideal curative properties in a mouse model of alcohol-induced liver injury without causing damage to other organs. This work suggests that Gal-HA/SIL-SLNPs with dual modification may represent an encouraging approach for developing more effective liver targeted nano-drug delivery systems to achieve accurate medication for alcoholic liver injury.

Amifostine loaded lipid-calcium carbonate nanoparticles as an oral drug delivery system for radiation protection

Amifostine (AMF) as the first-line radiation protection drug, usually suffered from low compliance and short half-life upon clinical applications. The development of oral drug delivery system (DDS) for AMF is a promising solution. However, the inherent shortages of AMF present significant challenges in the design of suitable oral DDS. Here in this study, we utilized the ability of calcium ions to bind with AMF and prepared AMF loaded calcium carbonate (CC) core, CC/AMF, using phase transferred coprecipitation method. We further modified the CC/AMF using phospholipids to prepare AMF loaded lipid-calcium carbonate (LCC) hybrid nanoparticles (LCC/AMF) via a thin-film dispersion method. LCC/AMF combines the oral advantages of lipid nanoparticles with the drug-loading capabilities of CC, which was shown as uniform nano-sized formulation with decent stability in aqueous solution. With favorable intestinal transport and absorption effects, it effectively enhances the in vivo radiation protection efficacy of AMF through oral administration. More importantly, we further investigated the cellular accumulation profile and intracellular transport mechanism of LCC/AMF using MDCK and Caco-2 cell lines as models. This research not only alters the current administration method of AMF to enhance its convenience and compliance, but also provides insights and guidance for the development of more suitable oral DDS for AMF in the future.

Fabrication and characteristics of multifunctional hydrogel dressings using dopamine modified hyaluronic acid and phenylboronic acid modified chitosan

The healing of damaged skin is a complex and dynamic process, and the multi-functional hydrogel dressings could promote skin tissue healing. This study, therefore, explored the development of a composite multifunctional hydrogel (HDCP) by incorporating the dopamine modified hyaluronic acid (HA-DA) and phenylboronic acid modified chitosan (CS-PBA) crosslinked using boric acid ester bonds. The integration of HA-DA and CS-PBA could be confirmed using the Fourier transform infrared spectrometer and 1H nuclear magnetic resonance analyses. The fabricated HDCP hydrogels exhibited porous structure, elastic solid behavior, shear-thinning, and adhesion properties. Furthermore, the HDCP hydrogels exhibited antibacterial efficacy against Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus). Subsequently, the cytocompatibility of the HDCP hydrogels was verified through CCK-8 assay and fluorescent image analysis following co-cultivation with NIH-3T3 cells. This research presents an innovative multifunctional hydrogel that holds promise as a wound dressing for various applications within the realm of wound healing.

Organic-inorganic composite hydrogels: compositions, properties, and applications in regenerative medicine

Hydrogels, formed from crosslinked hydrophilic macromolecules, provide a three-dimensional microenvironment that mimics the extracellular matrix. They served as scaffold materials in regenerative medicine with an ever-growing demand. However, hydrogels composed of only organic components may not fully meet the performance and functionalization requirements for various tissue defects. Composite hydrogels, containing inorganic components, have attracted tremendous attention due to their unique compositions and properties. Rigid inorganic particles, rods, fibers, etc., can form organic-inorganic composite hydrogels through physical interaction and chemical bonding with polymer chains, which can not only adjust strength and modulus, but also act as carriers of bioactive components, enhancing the properties and biological functions of the composite hydrogels. Notably, incorporating environmental or stimulus-responsive inorganic particles imparts smartness to hydrogels, hence providing a flexible diagnostic platform for in vitro cell culture and in vivo tissue regeneration. In this review, we discuss and compare a set of materials currently used for developing organic-inorganic composite hydrogels, including the modification strategies for organic and inorganic components and their unique contributions to regenerative medicine. Specific emphasis is placed on the interactions between the organic or inorganic components and the biological functions introduced by the inorganic components. The advantages of these composite hydrogels indicate their potential to offer adaptable and intelligent therapeutic solutions for diverse tissue repair demands within the realm of regenerative medicine.

Research Advances in Superabsorbent Polymers

Superabsorbent polymers are new functional polymeric materials that can absorb and retain liquids thousands of times their masses. This paper reviews the synthesis and modification methods of different superabsorbent polymers, summarizes the processing methods for different forms of superabsorbent polymers, and organizes the applications and research progress of superabsorbent polymers in industrial, agricultural, and biomedical industries. Synthetic polymers like polyacrylic acid, polyacrylamide, polyacrylonitrile, and polyvinyl alcohol exhibit superior water absorption properties compared to natural polymers such as cellulose, chitosan, and starch, but they also do not degrade easily. Consequently, it is often necessary to modify synthetic polymers or graft superabsorbent functional groups onto natural polymers, and then crosslink them to balance the properties of material. Compared to the widely used superabsorbent nanoparticles, research on superabsorbent fibers and gels is on the rise, and they are particularly notable in biomedical fields like drug delivery, wound dressing, and tissue engineering.

An updated landscape on nanotechnology-based drug delivery, immunotherapy, vaccinations, imaging, and biomarker detections for cancers: recent trends and future directions with clinical success

The recent development of nanotechnology-based formulations improved the diagnostics and therapies for various diseases including cancer where lack of specificity, high cytotoxicity with various side effects, poor biocompatibility, and increasing cases of multi-drug resistance are the major limitations of existing chemotherapy. Nanoparticle-based drug delivery enhances the stability and bioavailability of many drugs, thereby increasing tissue penetration and targeted delivery with improved efficacy against the tumour cells. Easy surface functionalization and encapsulation properties allow various antigens and tumour cell lysates to be delivered in the form of nanovaccines with improved immune response. The nanoparticles (NPs) due to their smaller size and associated optical, physical, and mechanical properties have evolved as biosensors with high sensitivity and specificity for the detection of various markers including nucleic acids, protein/antigens, small metabolites, etc. This review gives, initially, a concise update on drug delivery using different nanoscale platforms like liposomes, dendrimers, polymeric & various metallic NPs, hydrogels, microneedles, nanofibres, nanoemulsions, etc. Drug delivery with recent technologies like quantum dots (QDs), carbon nanotubes (CNTs), protein, and upconverting NPs was updated, thereafter. We also summarized the recent progress in vaccination strategy, immunotherapy involving immune checkpoint inhibitors, and biomarker detection for various cancers based on nanoplatforms. At last, we gave a detailed picture of the current nanomedicines in clinical trials and their possible success along with the existing approved ones. In short, this review provides an updated complete landscape of applications of wide NP-based drug delivery, vaccinations, immunotherapy, biomarker detection & imaging for various cancers with a predicted future of nanomedicines that are in clinical trials.

Advances of Amifostine in Radiation Protection: Administration and Delivery

Amifostine (AMF, also known as WR-2721) is the only approved broad-spectrum small-molecule radiation protection agent that can combat hematopoietic damage caused by ionizing radiation and is used as an antitumor adjuvant and cell protector in cancer chemotherapy and radiotherapy. Amifostine is usually injected intravenously before chemotherapy or radiotherapy and has been used in the treatment of head and neck cancer. However, the inconvenient intravenous administration and its toxic side effects such as hypotension have severely limited its further application in clinic. In order to reduce the toxic and side effects, scientists are trying to develop a variety of drug administration methods and are devoted to developing a wide application of amifostine in radiation protection. This paper reviews the research progress of amifostine for radiation protection in recent years, discusses its mechanism of action, clinical application, and other aspects, with focus on summarizing the most widely studied amifostine injection administration and drug delivery systems, and explored the correlation between various administrations and drug efficacies.

Three-Dimensional Printing Multi-Drug Delivery Core/Shell Fiber Systems with Designed Release Capability

A hydrogel system with the ability to control the delivery of multiple drugs has gained increasing interest for localized disease treatment and tissue engineering applications. In this study, a triple-drug-loaded model based on a core/shell fiber system (CFS) was fabricated through the co-axial 3D printing of hydrogel inks. A CFS with drug 1 loaded in the core, drug 2 in the shell part, and drug 3 in the hollow channel of the CFS was printed on a rotating collector using a co-axial nozzle. Doxorubicin (DOX), as the model drug, was selected to load in the core, with the shell and channel part of the CFS represented as drugs 1, 2, and 3, respectively. Drug 2 achieved the fastest release, while drug 3 showed the slowest release, which indicated that the three types of drugs printed on the CFS spatially can achieve sequential triple-drug release. Moreover, the release rate and sustained duration of each drug could be controlled by the unique core/shell helical structure, the concentration of alginate gels, the cross-linking density, the size and number of the open orifices in the fibers, and the CFS. Additionally, a near-infrared (NIR) laser or pH-responsive drug release could also be realized by introducing photo-thermal materials or a pH-sensitive polymer into this system. Finally, the drug-loaded system showed effective localized cancer therapy in vitro and in vivo. Therefore, this prepared CFS showed the potential application for disease treatment and tissue engineering by sequential- or stimulus-responsively releasing multi-drugs.

ROS-Responsive and pH-Sensitive Aminothiols Dual-Prodrug for Radiation Enteritis

Radiation exposure can immediately trigger a burst of reactive oxygen species (ROS), which can induce severe cell death and long-term tissue damage. Therefore, instantaneous release of sufficient radioprotective drugs is vital to neutralize those accumulated ROS in IR-exposed areas. To achieve this goal, we designed, synthesized, and evaluated a novel oral ROS-responsive radioprotective compound (M1) with high biocompatibility and efficient ROS-scavenging ability to act as a promising oral drug for radiation protection. The compound is stably present in acidic environments and is hydrolyzed in the intestine to form active molecules rich in thiols. M1 can significantly remove cellular ROS and reduce DNA damage induced by γ-ray radiation. An in vivo experiment showed that oral administration of M1 effectively alleviates acute radiation-induced intestinal injury. Immunohistochemical staining showed that M1 improved cell proliferation, reduced cell apoptosis, and enhanced the epithelial integrity of intestinal crypts. This study provides a promising oral ROS-sensitive agent for acute intestinal radiation syndrome.

Preparation and application of pH-responsive drug delivery systems

Microenvironment-responsive drug delivery systems (DDSs) can achieve targeted drug delivery, reduce drug side effects and improve drug efficacies. Among them, pH-responsive DDSs have gained popularity since the pH in the diseased tissues such as cancer, bacterial infection and inflammation differs from a physiological pH of 7.4 and this difference could be harnessed for DDSs to release encapsulated drugs specifically to these diseased tissues. A variety of synthetic approaches have been developed to prepare pH-sensitive DDSs, including introduction of a variety of pH-sensitive chemical bonds or protonated/deprotonated chemical groups. A myriad of nano DDSs have been explored to be pH-responsive, including liposomes, micelles, hydrogels, dendritic macromolecules and organic-inorganic hybrid nanoparticles, and micron level microspheres. The prodrugs from drug-loaded pH-sensitive nano DDSs have been applied in research on anticancer therapy and diagnosis of cancer, inflammation, antibacterial infection, and neurological diseases. We have systematically summarized synthesis strategies of pH-stimulating DDSs, illustrated commonly used and recently developed nanocarriers for these DDSs and covered their potential in different biomedical applications, which may spark new ideas for the development and application of pH-sensitive nano DDSs.

Hydrogels: Properties and Applications in Biomedicine

Hydrogels are crosslinked polymer chains with three-dimensional (3D) network structures, which can absorb relatively large amounts of fluid. Because of the high water content, soft structure, and porosity of hydrogels, they closely resemble living tissues. Research in recent years shows that hydrogels have been applied in various fields, such as agriculture, biomaterials, the food industry, drug delivery, tissue engineering, and regenerative medicine. Along with the underlying technology improvements of hydrogel development, hydrogels can be expected to be applied in more fields. Although not all hydrogels have good biodegradability and biocompatibility, such as synthetic hydrogels (polyvinyl alcohol, polyacrylamide, polyethylene glycol hydrogels, etc.), their biodegradability and biocompatibility can be adjusted by modification of their functional group or incorporation of natural polymers. Hence, scientists are still interested in the biomedical applications of hydrogels due to their creative adjustability for different uses. In this review, we first introduce the basic information of hydrogels, such as structure, classification, and synthesis. Then, we further describe the recent applications of hydrogels in 3D cell cultures, drug delivery, wound dressing, and tissue engineering.

Emerging Fabrication Strategies of Hydrogels and Its Applications

Recently, hydrogels have been investigated for the controlled release of bioactive molecules, such as for living cell encapsulation and matrices. Due to their remote controllability and quick response, hydrogels are widely used for various applications, including drug delivery. The rate and extent to which the drugs reach their targets are highly dependent on the carriers used in drug delivery systems; therefore the demand for biodegradable and intelligent carriers is progressively increasing. The biodegradable nature of hydrogel has created much interest for its use in drug delivery systems. The first part of this review focuses on emerging fabrication strategies of hydrogel, including physical and chemical cross-linking, as well as radiation cross-linking. The second part describes the applications of hydrogels in various fields, including drug delivery systems. In the end, an overview of the application of hydrogels prepared from several natural polymers in drug delivery is presented.

Fabrication, Evaluation, In Vivo Pharmacokinetic and Toxicological Analysis of pH-Sensitive Eudragit S-100-Coated Hydrogel Beads: a Promising Strategy for Colon Targeting

The aim of present research aims to fabricate a system of enteric coating of hydrogel beads with pH-sensitive polymer, which shows solubility at pH > 7, and explore their potential to target the colon for drug delivery. Hydrogel beads were fabricated through the extrusion-dripping technique followed by ion gelation crosslinking. Moreover, freeze-thaw cycle was implemented for crosslinking of polyvinyl alcohol (PVA)/Ca-alginate blend beads. The oil-in-oil solvent evaporation method was adopted for the Eudragit coating of hydrogel beads using different coat: core ratios (4:1 or 8:1). Coated and uncoated hydrogel beads were evaluated by in vitro physicochemical properties, swelling and drug release behaviours, and in vivo pharmacokinetics, swelling, and toxicity evaluation. Diclofenac sodium was loaded as an experimental drug. Drug entrapment efficiency for the PVA/Ca-alginate beads was calculated as 98%, and for Ca-alginate beads, it came out to a maximum of 74%. Drug release study at various pH suggested that, unlike uncoated hydrogel beads, the coated beads delay the release of diclofenac sodium in low pH of the gastric and intestinal environment, thus targeting the colon for the drug release. It was concluded that Eudragit S-100-coated hydrogel beads could serve as a more promising and reliable way to target the colon for drug delivery.Graphical abstract.

Superabsorbent polymers: A state-of-art review on their classification, synthesis, physicochemical properties, and applications

Superabsorbent polymers (SAP) and modified natural polymer hydrogels are widely and increasingly used in agriculture, health care textiles, effluent treatment, drug delivery, tissue engineering, civil concrete structure, etc. However, not many comprehensive reviews are available on this class of novel polymers. A review covering all the viable applications of SAP will be highly useful for researchers, industry persons, and medical, healthcare, and agricultural purposes. Hence, an attempt has been made to review SAPs with reference to their classifications, synthesis, modification by crosslinking, and physicochemical characterization such as morphology, swellability, thermal and mechanical properties, lifetime prediction, thermodynamics of swelling, absorption, release and transport kinetics, quantification of hydrophilic groups, etc. Besides, the possible methods of fine-tuning their structures for improving their absorption capacity, fast absorption kinetics, mechanical strength, controlled release features, etc. were also addressed to widen their uses. This review has also highlighted the biodegradability, commercial viability and market potential of SAPs, SAP composites, the feasibility of using biomass as raw materials for SAP production, etc. The challenges and future prospects of SAP, their safety, and environmental issues are also discussed.

Stimuli-Responsive Hydrogels for Cancer Treatment: The Role of pH, Light, Ionic Strength and Magnetic Field

Cancer remains as the second leading cause of death, worldwide. Despite the enormous important advances observed in the last decades, advanced stages of the disease remain incurable. The severe side effects associated to systemic high doses of chemotherapy and the development of drug resistance impairs a safe and efficiency anticancer therapy. Therefore, new formulations are continuously under research and development to improve anticancer drugs therapeutic index through localized delivery at tumor sites. Among a wide range of possibilities, hydrogels have recently gained special attention due to their potential to allow in situ sustained and controlled anticancer drug release. In particular, stimuli-responsive hydrogels which are able to change their physical state from liquid to gel accordingly to external factors such as temperature, pH, light, ionic strength, and magnetic field, among others. Some of these formulations presented promising results for the localized control and treatment of cancer. The present work aims to discuss the main properties and application of stimuli-responsive hydrogels in cancer treatment and summarize the most important advances observed in the last decades focusing on the use of pH-, light-, ionic strength-, and magnetic-responsive hydrogels.

Emerging Role of Hydrogels in Drug Delivery Systems, Tissue Engineering and Wound Management

The popularity of hydrogels as biomaterials lies in their tunable physical properties, ability to encapsulate small molecules and macromolecular drugs, water holding capacity, flexibility, and controllable degradability. Functionalization strategies to overcome the deficiencies of conventional hydrogels and expand the role of advanced hydrogels such as DNA hydrogels are extensively discussed in this review. Different types of cross-linking techniques, materials utilized, procedures, advantages, and disadvantages covering hydrogels are tabulated. The application of hydrogels, particularly in buccal, oral, vaginal, and transdermal drug delivery systems, are described. The review also focuses on composite hydrogels with enhanced properties that are being developed to meet the diverse demand of wound dressing materials. The unique advantages of hydrogel nanoparticles in targeted and intracellular delivery of various therapeutic agents are explained. Furthermore, different types of hydrogel-based materials utilized for tissue engineering applications and fabrication of contact lens are discussed. The article also provides an overview of selected examples of commercial products launched particularly in the area of oral and ocular drug delivery systems and wound dressing materials. Hydrogels can be prepared with a wide variety of properties, achieving biostable, bioresorbable, and biodegradable polymer matrices, whose mechanical properties and degree of swelling are tailored with a specific application. These unique features give them a promising future in the fields of drug delivery systems and applied biomedicine.

Preclinical Evaluation of Safety, Pharmacokinetics, Efficacy, and Mechanism of Radioprotective Agent HL-003

Amifostine is a radioprotector with high efficacy but poor safety, short half-life, no oral formulation, and poor compliance, which limits its application. With the increasing risk of exposure to radiation, the development of new radioprotective agents is critical. We previously synthesized a new amifostine derivative, the small molecule compound HL-003. In this study, we focused on evaluating the radioprotective properties of HL-003. Using the in vitro 2,2-diphenyl-1-picrylhydrazyl assay, we initially confirmed HL-003 as a strong antioxidant and demonstrated that its free radical scavenging activity was stronger than that of amifostine. Then, we performed an acute toxicity test, a 28-day toxicity test, a 30-day survival rate test, and a pharmacokinetic study, all of which provided aggregate evidence that HL-003 functioned as a small molecule radioprotector with high efficacy, a favorable safety profile, a long half-life, and oral administration. The intestinal radioprotective mechanism of HL-003 was explored in male C57 mice after abdominal irradiation by analyzing intestinal tissue samples with hematoxylin-eosin staining, immunohistochemistry, TUNEL staining, and immunofluorescence detection. The results showed that HL-003 protected intestinal DNA from radiation damage and suppressed the expression of phosphorylated histone H2AX, phosphorylated p53, and the apoptosis-related proteins caspase-8 and caspase-9, which contributed to maintaining the normal morphology of the small intestine and provided insights into the mechanism of radioprotection. Thus, HL-003 is a small molecule radioprotector with a potential application in radiation medicine.