Preparation and Drug Release Properties of a Thermo Sensitive GA Hydrogel

Enhanced wound healing and antimicrobial efficacy of PHMB-loaded injectable chitosan/quaternary chitosan/NaHCO3/β-glycerophosphate hydrogels for seawater-infected wounds

Bacterial infection is often linked to delayed wound healing. Seawater immersion further increases the risk of wound infection from bacteria in the water. A suitable wound environment is important for healing. In this study, to promote the healing of seawater immersion wounds, an injectable thermosensitive chitosan /quaternary chitosan/NaHCO3/β-glycerophosphate hydrogel wound dressings loaded with polyhexamethylene biguanide (PHMB) was developed. The physicochemical properties of the hydrogel were characterized, and antimicrobial and wound-healing capabilities were assessed. The hydrogel showed rapid gelling (2 min) at physiological temperature (35.15 °C), exhibiting adequate mechanical properties and enhanced network. The hydrogel demonstrates the ability to release 79.9 % of PHMB within 6 h. It also exhibits favorable adhesion and biocompatibility profile, characterized by a hemolysis ratio that remains below the 2 % threshold. In addition, the hydrogel loaded with 1 mg/mL PHMB demonstrated excellent antimicrobial properties both in vivo and in vitro. Furthermore, the hydrogel can reduce inflammatory cells, increase collagen fibre deposition and promote angiogenesis, demonstrating a high healing rate (95.03 % after 14 days) for wounds immersed in seawater. In summary, this injectable thermosensitive hydrogel shows great potential as a multifunctional dressing for treating complex bacterial wound infections and seawater-immersed wounds.

The Printed Path to Healing: Advancing Wound Dressings through Additive Manufacturing

Wound care challenges healthcare systems worldwide as traditional dressings often fall short in addressing the diverse and complex nature of wound healing. Given conventional treatments limitations, innovative alternatives are urgent. Additive manufacturing (AM) has emerged as a distinct and transformative approach for developing advanced wound dressings, offering unprecedented functionality and customization. Besides exploring the AM processes state-of-the-art, this review comprehensively examines the application of AM to produce cellular-compatible and bioactive, therapeutic agent delivery, patient-centric, and responsive dressings. This review distinguishes itself from the published literature by covering a variety of wound types and by summarizing important data, including used materials, process/technology, printing parameters, and findings from in vitro, ex vivo, and in vivo studies. The prospects of AM in enhancing wound healing outcomes are also analyzed in a translational and cost-effective manner.

Recent progress on media for biological sample preparation

The analysis of biological samples is highly valuable for disease diagnosis and treatment, forensic examination, and public safety. However, the serious matrix interference effect generated by biological samples severely affects the analysis of trace analytes. Sample preparation methods are introduced to address the limitation by extracting, separating, enriching, purifying trace target analytes from biological samples. With the raising demand of biological sample analysis, a review focuses on media for biological sample preparation and analysis over the last 5 years is presented. High-performance media in biological sample preparation are first reviewed, including porous organic frameworks, imprinted polymers, hydrogels, ionic liquids, and bioactive media. Then, application of media for different biological sample preparation and analysis is briefly introduced, including liquid samples of body fluids, solid samples (hair, feces, and tissues), and gas samples of exhale breath gas. Finally, conclusions and outlooks on media promoting biological sample preparation are presented.

Unlocking the potential of stimuli-responsive biomaterials for bone regeneration

Bone defects caused by tumors, osteoarthritis, and osteoporosis attract great attention. Because of outstanding biocompatibility, osteogenesis promotion, and less secondary infection incidence ratio, stimuli-responsive biomaterials are increasingly used to manage this issue. These biomaterials respond to certain stimuli, changing their mechanical properties, shape, or drug release rate accordingly. Thereafter, the activated materials exert instructive or triggering effects on cells and tissues, match the properties of the original bone tissues, establish tight connection with ambient hard tissue, and provide suitable mechanical strength. In this review, basic definitions of different categories of stimuli-responsive biomaterials are presented. Moreover, possible mechanisms, advanced studies, and pros and cons of each classification are discussed and analyzed. This review aims to provide an outlook on the future developments in stimuli-responsive biomaterials.

Response strategies and biological applications of organic fluorescent thermometry: cell- and mitochondrion-level detection

Temperature homeostasis is critical for cells to perform their physiological functions. Among the diverse methods for temperature detection, fluorescent temperature probes stand out as a proven and effective tool, especially for monitoring temperature in cells and suborganelles, with a specific emphasis on mitochondria. The utilization of these probes provides a new opportunity to enhance our understanding of the mechanisms and interconnections underlying various physiological activities related to temperature homeostasis. However, the complexity and variability of cells and suborganelles necessitate fluorescent temperature probes with high resolution and sensitivity. To meet the demanding requirements for intracellular/subcellular temperature detection, several strategies have been developed, offering a range of options to address this challenge. This review examines four fundamental temperature-response strategies employed by small molecule and polymer probes, including intramolecular rotation, polarity sensitivity, Förster resonance energy transfer, and structural changes. The primary emphasis was placed on elucidating molecular design and biological applications specific to each type of probe. Furthermore, this review provides an insightful discussion on factors that may affect fluorescent thermometry, providing valuable perspectives for future development in the field. Finally, the review concludes by presenting cutting-edge response strategies and research insights for mitigating biases in temperature sensing.

The role of smart polymeric biomaterials in bone regeneration: a review

Addressing critical bone defects necessitates innovative solutions beyond traditional methods, which are constrained by issues such as immune rejection and donor scarcity. Smart polymeric biomaterials that respond to external stimuli have emerged as a promising alternative, fostering endogenous bone regeneration. Light-responsive polymers, employed in 3D-printed scaffolds and photothermal therapies, enhance antibacterial efficiency and bone repair. Thermo-responsive biomaterials show promise in controlled bioactive agent release, stimulating osteocyte differentiation and bone regeneration. Further, the integration of conductive elements into polymers improves electrical signal transmission, influencing cellular behavior positively. Innovations include advanced 3D-printed poly (l-lactic acid) scaffolds, polyurethane foam scaffolds promoting cell differentiation, and responsive polymeric biomaterials for osteogenic and antibacterial drug delivery. Other developments focus on enzyme-responsive and redox-responsive polymers, which offer potential for bone regeneration and combat infection. Biomaterials responsive to mechanical, magnetic, and acoustic stimuli also show potential in bone regeneration, including mechanically-responsive polymers, magnetic-responsive biomaterials with superparamagnetic iron oxide nanoparticles, and acoustic-responsive biomaterials. In conclusion, smart biopolymers are reshaping scaffold design and bone regeneration strategies. However, understanding their advantages and limitations is vital, indicating the need for continued exploratory research.

Dispersion Performances of Naphthalimides Doped in Dual Temperature- and pH-Sensitive Poly (N-Isopropylacrylamide-co-acrylic Acid) Shell Assembled with Vinyl-Modified Mesoporous SiO2 Core for Fluorescence Cell Imaging

Developing effective intelligent nanocarriers is highly desirable for fluorescence imaging and therapeutic applications but remains challenging. Using a vinyl-grafted BMMs (bimodal mesoporous SiO₂ materials) as a core and PAN ((2-aminoethyl)-6-(dimethylamino)-1H-benzo[de]isoquinoline-1,3(2H)-dione))-dispersed dual pH/thermal-sensitive poly(N-isopropylacrylamide-co-acrylic acid) as a shell, PAN@BMMs with strong fluorescence and good dispersibility were prepared. Their mesoporous features and physicochemical properties were extensively characterized via XRD patterns, N₂ adsorption-desorption analysis, SEM/TEM images, TGA profiles, and FT-IR spectra. In particular, their mass fractal dimension (d_m) features based on SAXS patterns combined with fluorescence spectra were successfully obtained to evaluate the uniformity of the fluorescence dispersions, showing that the d_m values increased from 2.49 to 2.70 with an increase of the AN-additive amount from 0.05 to 1%, along with the red shifting of their fluorescent emission wavelength from 471 to 488 nm. The composite (PAN@BMMs-I-0.1) presented a densification trend and a slight decrease in peak (490 nm) intensity during the shrinking process. Its fluorescent decay profiles confirmed two fluorescence lifetimes of 3.59 and 10.62 ns. The low cytotoxicity obtained via in vitro cell survival assay and the efficient green imaging performed via HeLa cell internalization suggested that the smart PAN@BMM composites are potential carriers for in vivo imaging and therapy.

Injectable Thermoresponsive Hydrogels for Cancer Therapy: Challenges and Prospects

The enervating side effects of chemotherapeutic drugs have necessitated the use of targeted drug delivery in cancer therapy. To that end, thermoresponsive hydrogels have been employed to improve the accumulation and maintenance of drug release at the tumour site. Despite their efficiency, very few thermoresponsive hydrogel-based drugs have undergone clinical trials, and even fewer have received FDA approval for cancer treatment. This review discusses the challenges of designing thermoresponsive hydrogels for cancer treatment and offers suggestions for these challenges as available in the literature. Furthermore, the argument for drug accumulation is challenged by the revelation of structural and functional barriers in tumours that may not support targeted drug release from hydrogels. Other highlights involve the demanding preparation process of thermoresponsive hydrogels, which often involves poor drug loading and difficulties in controlling the lower critical solution temperature and gelation kinetics. Additionally, the shortcomings in the administration process of thermosensitive hydrogels are examined, and special insight into the injectable thermosensitive hydrogels that reached clinical trials for cancer treatment is provided.

Preparation, thermal response mechanisms and biomedical applications of thermosensitive hydrogels for drug delivery

INTRODUCTION

Drug treatment is one of the main ways of coping with disease today. For the disadvantages of drug management, thermosensitive hydrogel is used as a countermeasure, which can realize the simple sustained release of drugs and the controlled release of drugs in complex physiological environments.

AREAS COVERED

This paper talks about thermosensitive hydrogels that can be used as drug carriers. The common preparation materials, material forms, thermal response mechanisms, characteristics of thermosensitive hydrogels for drug release and main disease treatment applications are reviewed.

EXPERT OPINION

When thermosensitive hydrogels are used as drug loading and delivery platforms, desired drug release patterns and release profiles can be tailored by selecting raw materials, thermal response mechanisms, and material forms. The properties of hydrogels prepared from synthetic polymers will be more stable than natural polymers. Integrating multiple thermosensitive mechanisms or different kinds of thermosensitive mechanisms on the same hydrogel is expected to realize the spatiotemporal differential delivery of multiple drugs under temperature stimulation. The industrial transformation of thermosensitive hydrogels as drug delivery platforms needs to meet some important conditions.

Multifunctional Oxidized Succinoglycan/Poly(N-isopropylacrylamide-co-acrylamide) Hydrogels for Drug Delivery

We prepared the self-healing and temperature/pH-responsive hydrogels using oxidized succinoglycan (OSG) and a poly (N-isopropyl acrylamide-co-acrylamide) [P(NIPAM-AM)] copolymer. OSG was synthesized by periodate oxidation of succinoglycan (SG) isolated directly from soil microorganisms, Sinorhizobium meliloti Rm1021. The OSG/P(NIPAM-AM) hydrogels were obtained by introducing OSG into P(NIPAM-AM) networks. The chemical structure and physical properties of these hydrogels were characterized by ATR-FTIR, XRD, TGA, and FE-SEM. The OSG/P(NIPAM-AM) hydrogels showed improved elasticity, increased thermal stability, new self-healing ability, and 4-fold enhanced tensile strength compared with the P(NIPAM-AM) hydrogels. Furthermore, the 5-FU-loaded OSG/P(NIPAM-AM) hydrogels exhibited effective temperature/pH-responsive drug release. Cytotoxicity experiments showed that the OSG/P(NIPAM-AM) hydrogels were non-toxic, suggesting that OSG/P(NIPAM-AM) hydrogels could have the potential for biomedical applications, such as stimuli-responsive drug delivery systems, wound healing, smart scaffolds, and tissue engineering.

The Nanostructured lipid carrier gel of Oroxylin A reduced UV-induced skin oxidative stress damage

Oxidative stress damage caused by sun exposure damages the appearance and function of the skin, which is one of the essential inducements of skin aging and even leads to skin cancer. Oroxylin A (OA) is a flavonoid with excellent antioxidant activity and has protective effects against photoaging induced by UV irradiation. However, the strong barrier function of the skin stratum corneum prevents transdermal absorption of the drug, which limits the application of OA in dermal drug delivery. Studies have shown that nanostructured lipid carriers (NLC) can promote not only transdermal absorption of drugs but also increase drug stability and control drug release efficiency, which has broad prospects for clinical applications. In this paper, NLC loaded with OA (OA-NLC) was prepared in order to improve the skin permeability and stability of OA. In vitro studies revealed that OA-NLC had better therapeutic effects than OA solution (OA-Sol) in the cellular model of UVB radiation. OA-Sol and OA-NLC were immobilized in a hydrogel matrix to facilitate application to the dorsal skin of mice. It was found that OA-NLC-gel showed significant antioxidant and anti-apoptotic activity compared to OA-Sol-gel, which was able to protect against skin damage in mice after UV radiation. These results suggest that OA-NLC can improve the deficiencies of OA in skin delivery and show better resistance to UV-induced oxidative damage. The application of OA-NLC to skin delivery systems has good prospects and deserves further development and investigation.

Investigation and Optimization of Hydrogel Microneedles for Transdermal Delivery of Caffeine

Caffeine is therapeutically effective for treating apnea, cellulite formation, and pain management. It also exhibits neuroprotective and antioxidant activities in different models of Parkinson's disease and Alzheimer's disease. However, caffeine administration in a minimally invasive and sustainable manner through the transdermal route is challenging owing to its hydrophilic nature. Therefore, this study demonstrated a transdermal delivery approach for caffeine by utilizing hydrogel microneedle (MN) as a permeation enhancer. The influence of formulation parameters such as molecular weight (MW) of PMVE/MA (polymethyl vinyl ether/maleic anhydride) copolymer and sodium bicarbonate (NaHCO₃) concentration on the swelling kinetics and mechanical integrity of the hydrogel MNs was investigated. In addition, the effect of different MN application methods and needle densities of hydrogel MN on the skin insertion efficiency and penetration depth was also evaluated. The swelling degree at equilibrium percentage (% S_eq) recorded for hydrogels fabricated with Gantrez S-97 (MW = 1,500,000 Da) was significantly higher than formulation with Gantrez AN-139 (MW = 1,080,000 Da). Increasing the concentration of NaHCO₃ also significantly increased the % S_eq. Moreover, a 100% penetration was recorded for both the applicator and combination of applicator and thumb pressure compared with only 11% for thumb pressure alone. The average diameter of micropores created by the applicator method was 62.94 μm, which was significantly lower than the combination of both applicator and thumb pressure MN application (100.53 μm). Based on histological imaging, the penetration depth of hydrogel MN increased as the MN density per array decreased. The hydrogel MN with the optimized formulation and skin insertion parameters was tested for caffeine delivery in an in vitro Franz diffusion cell setup. Approximately 2.9 mg of caffeine was delivered within 24 h, and the drug release profile was best fitted to the Korsmeyer-Peppas model, displaying Super Case II kinetics. In conclusion, a combination of thumb and impact application methods and reduced needle density improved the skin penetration efficiency of hydrogel MNs. The results also show that hydrogel MNs fabricated from 3% w/w NaHCO₃ and high MW of copolymer exhibit optimum physical and swelling properties for enhanced transdermal delivery.

Intelligent hydrogel with both redox and thermo-response based on cellulose nanofiber for controlled drug delivery

The purpose of this study is to develop a hydrogel with temperature and redox response to control drug delivery. However, the strength of temperature sensitive N-isopropylacrylamide (NIPAM) hydrogel is weak. Therefore, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidized cellulose nanofiber (CNF) is introduced to improve this problem. The compressive strength of hydrogels increased by 360% after CNF addition. Meanwhile, N,N'-bis(acryloyl)cystamine (BACy) is introduced into the hydrogels as a cross-linker, imparting redox responsive properties to the hydrogels. Tumor therapeutic drugs are used as model drugs for in vitro release studies. The drug release rate of hydrogel is regulated by temperature and reducing environment. The maximum cumulative release rate of doxorubicin (DOX) is 39.56%, and the Berberine (BBR) is 99.50% after 60 h. The swelling and transparency of hydrogels showed dramatic changes in the range of 30-40 °C. Cytotoxicity experiments demonstrated that the hydrogel had almost no cytotoxicity.

An injectable thermosensitive hydrogel with self-assembled peptide coupled with antimicrobial peptide for enhanced wound healing

Wound dressing based on thermosensitive hydrogel shows advantages over performed traditional dressings such as rapid reversible sol-gel-sol transition property and the capacity of filling the irregular wound area. Herein, RA-Amps...

Multi-responsive PNIPAM-PEGDA hydrogel composite

Hydrogels are widely used in applications such as soft robots and flexible sensors due to their sensitivity to environmental stimuli. It is highly demanded to develop multiple-responsive hydrogel structures. In this work, we employ the 3D printing technique to fabricate a PNIPAM-PEGDA hydrogel bilayer that can change shape through controlling the temperature, solvent mixture and magnetic field. The PNIPAM gel is a typical thermo-responsive gel, showing a decrease in swelling ratio with increasing temperature. Meanwhile, the PNIPAM gels also exhibit the cononsolvency effect in ethanol-water mixtures with a smaller swelling ratio in the mixture compared with that in each pure solvent. In comparison, the swelling ratio of PEGDA gels is insensitive to changes in both the temperature and solvent composition. Thus, the bilayer structure of PNIPAM-PEGDA can bend in different directions and with different angles with changing the temperature and solvent composition. Finally, Fe₃O₄ nanoparticles are incorporated into the matrix of PEGDA gels, endowing the whole structure with deformation and motion in response to an external magnetic field.

Development and evaluation studies of Corylin loaded nanostructured lipid carriers gel for topical treatment of UV-induced skin aging

We prepared nanostructured lipid carriers (NLC) to promote skin permeation of Corylin so that it can increase its effect on photoaging. Corylin-NLCs were prepared and characterized based on morphology, particle size, zeta potentials, FTIR and DSC. In vitro, we assess the cytotoxicity and lactate dehydrogenase (LDH) of HaCaT cells irradiated by UVB. Expression of antioxidant enzymes was evaluated by commercial kits. The effects of Corylin-NLC on apoptosis were confirmed by flow cytometry and western blotting. In vivo, we use UV irradiated mouse as the oxidative stress model to assess the therapeutic effect of Corylin loaded NLC gel. We identified the Corylin-NLCs can significantly suppress the LDH release, decrease MDA content, increase in CAT, SOD, GSH-Px activity, increase the expression of Bcl-2/Bax protein and reduce the expression of cleaved caspase-3/caspase-3 protein on UVB induced HaCaT cells. The histopathological lesions were significantly improved and observably decreased MDA level, increase in antioxidant enzymes activity in serum of mice by pretreatment of Corylin-NLCs gel. Overall, this study proposes a promising strategy for improving the therapeutic efficacy of photoaging.