The effect of pH on cell viability, cell migration, cell proliferation, wound closure, and wound reepithelialization: In vitro and in vivo study

Applications of mesenchymal stem cell-exosome components in wound infection healing: new insights

The healing process at a wound is made up of many types of cells, growth factors, the extracellular matrix, nerves and blood vessels all interacting with each other in complex and changing ways. Microbial colonization and proliferation are possible at the place of injury, which makes infection more likely. Because of this, any cut has a chance of getting an infection. Researchers have found that wound infections make patients more upset and cost the healthcare system a lot of money. Surgical site infections happen a lot to people who have recently had surgery. This study shows that such surgical infection is linked to a high rate of illness and death. This is shown by the fact that 25% of patients get serious sepsis and need to be transferred to an intensive care unit. In both animal models and people, mesenchymal stem cells (MSCs) play an active role in all stages of wound healing and have positive effects. Exosomes are one of the main things MSCs release. They have effects that are similar to those of the parent MSCs. Various effector proteins, messenger RNA and microRNAs can be transported by extracellular vesicles to control the activity of target cells. This has a big impact on the healing process. These results suggest that using MSC-exosomes as a new type of cell-free therapy could be a better and safer option than whole cell therapy. This review is mostly about how to use parts of MSC-exosomes to help wound infections heal.

Novel composite fatty acid vesicles-in-Pluronic lecithin organogels for enhanced magnolol delivery in skin cancer treatment

A novel composite carrier composed of Pluronic lecithin organogels and fatty acid vesicles was used to enhance the stability and facilitate the topical delivery of a natural bioactive drug, magnolol (Mag), for treatment of skin cancer. Jojoba oil was incorporated in the organogel (OG) base to provide a synergistic effect in treatment of skin cancer. The organoleptic properties, rheological behavior, morphology, and drug content of the OG formulations were investigated with emphasis on the impact of vesicle loading on the OG characteristics. The effect of OG on Mag release and ex-vivo permeation studies were evaluated and compared to free Mag in OG. The biological anti-tumor activity of the OG formulae was assessed using a skin cancer model in mice. All OG formulations exhibited uniform drug distribution with drug content ranging from 92.22 ± 0.91 to 100.45 ± 0.77 %. Rheological studies confirmed the OG shear-thinning flow behavior. Ex-vivo permeation studies demonstrated that the permeation of Mag from all OG formulations surpassed that obtained with free Mag in the OG. The anti-tumor activity studies revealed the superior efficacy of 10-hydroxy-decanoic acid (HDA)-based vesicles incorporated in OG formulations in mitigating 7,12- dimethylbenz(a)anthracene (DMBA)-induced skin cancer, thereby offering a promising platform for the local delivery of Mag.

Supramolecular interaction in the action of drug delivery systems

Complex diseases and diverse clinical needs necessitate drug delivery systems (DDSs), yet the current performance of DDSs is far from ideal. Supramolecular interactions play a pivotal role in various aspects of drug delivery, encompassing biocompatibility, drug loading, stability, crossing biological barriers, targeting, and controlled release. Nevertheless, despite having some understanding of the role of supramolecular interactions in drug delivery, their incorporation is frequently overlooked in the design and development of DDSs. This perspective provides a brief analysis of the involved supramolecular interactions in the action of drug delivery, with a primary emphasis on the DDSs employed in the clinic, mainly liposomes and polymers, and recognized phenomena in research, such as the protein corona. The supramolecular interactions implicated in various aspects of drug delivery systems, including biocompatibility, drug loading, stability, spatiotemporal distribution, and controlled release, were individually analyzed and discussed. This perspective aims to trigger a comprehensive and systematic consideration of supramolecular interactions in the further development of DDSs. Supramolecular interactions embody the true essence of the interplay between the majority of DDSs and biological systems.

A pro-reparative bioelectronic device for controlled delivery of ions and biomolecules

Wound healing is a complex physiological process that requires precise control and modulation of many parameters. Therapeutic ion and biomolecule delivery has the capability to regulate the wound healing process beneficially. However, achieving controlled delivery through a compact device with the ability to deliver multiple therapeutic species can be a challenge. Bioelectronic devices have emerged as a promising approach for therapeutic delivery. Here, we present a pro-reparative bioelectronic device designed to deliver ions and biomolecules for wound healing applications. The device incorporates ion pumps for the targeted delivery of H+ and zolmitriptan to the wound site. In vivo studies using a mouse model further validated the device's potential for modulating the wound environment via H+ delivery that decreased M1/M2 macrophage ratios. Overall, this bioelectronic ion pump demonstrates potential for accelerating wound healing via targeted and controlled delivery of therapeutic agents to wounds. Continued optimization and development of this device could not only lead to significant advancements in tissue repair and wound healing strategies but also reveal new physiological information about the dynamic wound environment.

Ultrasensitive Nanofiber Biosensor: Rapid In Situ Chromatic Detection of Bacteria for Healthcare Innovation

Rapid detection of bacterial presence in skin wounds is crucial to prevent the transition from acute to chronic wounds and the onset of systemic infections. Current methods for detecting infections, particularly at low concentrations (<1.0 × 105 CFU/cm2), often require complex technologies and direct sampling, which can be invasive and time-consuming. Addressing this gap, we introduce a colorimetric nanofibrous biosensor enabling real-time in situ monitoring of bacterial concentrations in wounds. This biosensor employs a colorimetric hemicyanine dye (HCy) probe, which changes color in response to bacterial lipase, a common secretion in infected wounds. To enhance the biosensor's sensitivity, we incorporated two key materials science strategies: aligning the nanofibers to promote efficient bacterial attachment and localization and integrating Tween 80, a surfactant, within the nanofiber matrix. This combination of physical and chemical cues results in a notable increase in lipase activity. The cross-aligned core-shell nanofibers, embedded with Tween 80 and HCy, demonstrate an immediate and distinct color change when exposed to as low as 3.0 × 104 CFU/cm2 of common pathogens such as Pseudomonas aeruginosa and MRSA. Significantly, the presence of Tween 80 amplifies the colorimetric response, making visual detection more straightforward and four times more pronounced. Our nanobiosensor design facilitates the detection of low-concentration bacterial infections in situ without the need to remove wound dressings. This advancement marks a significant step forward in real-time wound monitoring, offering a practical tool for the early detection of clinical bacterial infections.

CARBON DOTS: Bioimaging and Anticancer Drug Delivery

Cancer, responsible for approximately 10 million lives annually, urgently requires innovative treatments, as well as solutions to mitigate the limitations of traditional chemotherapy, such as long-term adverse side effects and multidrug resistance. This review focuses on Carbon Dots (CDs), an emergent class of nanoparticles (NPs) with remarkable physicochemical and biological properties, and their burgeoning applications in bioimaging and as nanocarriers in drug delivery systems for cancer treatment. The review initiates with an overview of NPs as nanocarriers, followed by an in-depth look into the biological barriers that could affect their distribution, from barriers to administration, to intracellular trafficking. It further explores CDs' synthesis, including both bottom-up and top-down approaches, and their notable biocompatibility, supported by a selection of in vitro, in vivo, and ex vivo studies. Special attention is given to CDs' role in bioimaging, highlighting their optical properties. The discussion extends to their emerging significance as drug carriers, particularly in the delivery of doxorubicin and other anticancer agents, underscoring recent advancements and challenges in this field. Finally, we showcase examples of other promising bioapplications of CDs, emergent owing to the NPs flexible design. As research on CDs evolves, we envisage key challenges, as well as the potential of CD-based systems in bioimaging and cancer therapy.

pH-regulated single cell migration

Over the last two decades, extra- and intracellular pH have emerged as fundamental regulators of cell motility. Fundamental physiological and pathological processes relying on appropriate cell migration, such as embryonic development, wound healing, and a proper immune defense on the one hand, and autoimmune diseases, metastatic cancer, and the progression of certain parasitic diseases on the other, depend on surrounding pH. In addition, migrating single cells create their own localized pH nanodomains at their surface and in the cytosol. By this means, the migrating cells locally modulate their adhesion to, and the re-arrangement and digestion of, the extracellular matrix. At the same time, the cytosolic nanodomains tune cytoskeletal dynamics along the direction of movement resulting in concerted lamellipodia protrusion and rear end retraction. Extracellular pH gradients as found in wounds, inflamed tissues, or the periphery of tumors stimulate directed cell migration, and long-term exposure to acidic conditions can engender a more migratory and invasive phenotype persisting for hours up to several generations of cells after they have left the acidic milieu. In the present review, the different variants of pH-dependent single cell migration are described. The underlying pH-dependent molecular mechanisms such as conformational changes of adhesion molecules, matrix protease activity, actin (de-)polymerization, and signaling events are explained, and molecular pH sensors stimulated by H+ signaling are presented.

Enteromorpha Prolifera Polysaccharide-Derived Injectable Hydrogel for Fast Intraoperative Hemostasis and Accelerated Postsurgical Wound Healing Following Tumor Resection

Intraoperative bleeding and delayed postsurgical wound healing caused by persistent inflammation can increase the risk of tumor recurrence after surgical resection. To address these issues, Enteromorpha prolifera polysaccharide (PEP) with intrinsic potentials for hemostasis and wound healing, is chemically modified into aldehyde-PEP and hydrazine-PEP. Thereby, an injectable double-network hydrogel (OPAB) is developed via forming dual dynamic bonding of acylhydrazone bonds between the decorated aldehyde and hydrazine groups and hydrogen bonds between hydroxyl groups between boric acid and PEP skeletons. The OPAB exhibits controllable shape-adaptive gelation (35.0 s), suitable mechanical properties, nonstimulating self-healing (60 s), good wet tissue adhesion (30.9 kPa), and pH-responsive biodegradability. For in vivo models, owing to these properties, OPAB can achieve rapid hemostasis within 30 s for the liver hemorrhage, and readily loading of curcumin nanoparticles to remarkably accelerate surgical wound closure by alleviating inflammation, re-epithelialization, granulation tissue formation, and collagen deposition. Overall, this multifunctional injectable hydrogel is a promising material that facilitates simultaneous intraoperative hemorrhage and postsurgical wound repair, holding significant potential in the clinical managements of bleeding and surgical wounds for tumor resection.

CO2-Mediated Alkali-Neutralization Curdlan Hydrogels for Potential Wound Healing Application

Physical hydrogels of natural polysaccharides are considered as ideal candidates for wound dressing due to their natural biological activity and no harmful cross-linking agents. However, it remains a challenge to fabricate such hydrogel dressings in a facile and low-cost way. Herein, we reported an easy and cost-effective method to construct CO2-mediated alkali-neutralization Curdlan (CR) hydrogels without using an external cross-linking agent. Two types of hydrogels (denoted as CR-NaOH and CR-Na3PO4, respectively) were fabricated by dissolving CR powders in a NaOH or Na3PO4 aqueous solution, followed by keeping the CR alkaline solutions in air. The obtained pure CR hydrogels possessed a tunable porous structure with walls containing different forms of nanofibrils. These hydrogels exhibited much higher gel strength by comparison with the gels prepared by conventional heating treatment. They were flexible, stretchable, twistable, and conformable to arbitrarily curved skins. Moreover, they exhibited ideal swellability, proper degradability, and water vapor transmission rate, and their physicochemical properties were closely related to CR concentration in the alkaline solution. These two hydrogels also supported the growth of L929 cells. Importantly, studies on wound healing revealed that both 3CR-NaOH and 3CR-Na3PO4 hydrogels were capable of accelerating the wound healing process through recruiting more macrophages/fibroblasts, inducing more collagen deposition and neovascularization (α-SMA and CD31) without carrying any exogenous bioactive components. In conclusion, the present work not only reported promising materials for application in wound therapy but also offered a facile and safe manufacturing procedure for generating pure CR physical hydrogels with better performance.

Paxillin/HDAC6 regulates microtubule acetylation to promote directional migration of keratinocytes driven by electric fields

Endogenous electric fields (EFs) have been demonstrated to facilitate wound healing by directing the migration of epidermal cells. Despite the identification of numerous molecules and signaling pathways that are crucial for the directional migration of keratinocytes under EFs, the underlying molecular mechanisms remain undefined. Previous studies have indicated that microtubule (MT) acetylation is linked to cell migration, while Paxillin exerts a significant influence on cell motility. Therefore, we postulated that Paxillin could enhance EF-induced directional migration of keratinocytes by modulating MT acetylation. In the present study, we observed that EFs (200 mV/mm) induced migration of human immortalized epidermal cells (HaCaT) towards the anode, while upregulating Paxillin, downregulating HDAC6, and increasing the level of microtubule acetylation. Our findings suggested that Paxillin plays a pivotal role in inhibiting HDAC6-mediated microtubule acetylation during directional migration under EF regulation. Conversely, downregulation of Paxillin decreased microtubule acetylation and electrotaxis of epidermal cells by promoting HDAC6 expression, and this effect could be reversed by the addition of tubacin, an HDAC6-specific inhibitor. Furthermore, we observed that EFs also mediated the polarization of Paxillin and acetylated α-tubulin, which is critical for directional migration. In conclusion, our study revealed that MT acetylation in EF-guided keratinocyte migration is regulated by the Paxillin/HDAC6 signaling pathway, providing a novel theoretical foundation for the molecular mechanism of EF-guided directional migration of keratinocytes.

In vitro biocompatibility of ammonia-free silver fluoride products on human dental pulp stem cells

OBJECTIVES

Silver fluoride (SF) is a preventive and therapeutic option for dental pathological processes involving structural alterations of the hard tissues, either during their formation or those caused by caries or other pathological reasons. This study aimed to compare the biological properties of two commercial SF products, one of them with ammonium (Riva Star; SDF) and the other ammonium-free (Riva Star Aqua; AgF), both with or without potassium iodide (KI), by the assessment of the cytotoxicity of the materials' eluates.

METHODS

Human dental pulp stem cells (hDPSCs) were obtained from healthy 18-23-year-old donors. Three dilutions were prepared for the tested materials (0.005%, 0.0005%, and 0.0001%). The following groups were assessed: (AgF, AgF+KI, SDF, SDF+KI, KI, negative control). A series of cytocompatibility assays were performed: MTT assay, IC50 assay, wound healing (migration) assay, cell cytoskeleton staining, analysis of cell apoptosis and necrosis, and reactive oxygen species production. The normality in the distribution of the data was previously confirmed via a Q-Q plot. Statistical significance was tested using one way ANOVA and Tukey's post hoc test.

RESULTS

The incorporation of KI improved the cytocompatibility of both SF products in terms of viability, migration, morphology, apoptosis, and reactive oxygen species production. This difference was higher in the AgF group. The lowest dilutions of SF+KI and AgF+KI showed a similar cytocompatibility to that of the control group (MTT assay (p > 0.05 after 24, 48, and 72 h of culture); migration assay (p > 0.05 after 24, 48, and 72 h of culture); reactive oxygen species production (p > 0.05 after 72 h of culture).

SIGNIFICANCE

Riva Star Aqua shows lower cytotoxicity than Riva Star on hDPSCs. It can be considered as a good alternative in the conservative treatment of dental caries and in the preservation and remineralisation of viable dentine tissue.

Biocompatible Rhamnolipid Self-Assemblies with pH-Responsive Antimicrobial Activity

There is an urgent need for alternative antimicrobial materials due to the growing challenge of bacteria becoming resistant to conventional antibiotics. This study demonstrates the creation of a biocompatible pH-switchable antimicrobial material by combining bacteria-derived rhamnolipids (RL) and food-grade glycerol monooleate (GMO). The integration of RL into dispersed GMO particles, with an inverse-type liquid crystalline cubic structure in the core, leads to colloidally stable supramolecular materials. The composition and pH-triggered structural transformations are studied with small-angle X-ray scattering, cryogenic transmission electron microscopy, and dynamic light scattering. The composition-structure-activity relationship is analyzed and optimized to target bacteria at acidic pH values of acute wounds. The new RL/GMO dispersions reduce Staphylococcus aureus (S. aureus) populations by 7-log after 24 h of treatment with 64 µg mL-1 of RL and prevent biofilm formation at pH = 5.0, but have no activity at pH = 7.0. Additionally, the system is active against methicillin-resistant S. aureus (MRSA) with minimum inhibitory concentration of 128 µg mL-1 at pH 5.0. No activity is found against several Gram-negative bacteria at pH 5.0 and 7.0. The results provide a fundamental understanding of lipid self-assembly and the design of lipid-based biomaterials, which can further guide the development of alternative bio-based solutions to combat bacteria.

Investigating Inflammatory Markers in Wound Healing: Understanding Implications and Identifying Artifacts

Understanding the complex interplay of pro-inflammatory and anti-inflammatory cytokines is crucial in the field of wound healing, as it holds the key to developing effective therapeutics. In the initial stages of wound healing, pro-inflammatory cytokines like IL-1β, IL-6, TNF-α, and various chemokines play vital roles in recruiting cells for debris clearance and the recruitment of growth factors. Careful regulation and timely resolution of this early inflammation are essential for optimal wound repair. As the healing process progresses, anti-inflammatory proteins such as IL-10 and IL-4 become instrumental in facilitating the transition to later stages where pro-inflammatory cytokines promote angiogenesis and wound remodeling. This Perspective underscores the complexity of inflammatory cytokines in wound healing research and emphasizes the need for comprehensive and unbiased methodologies in their evaluation. For robust and reliable results in wound-healing research, a more holistic approach is necessary-one that considers the roles, interactions, and timing of biological molecules, alongside careful sampling and evaluation strategies.

Double Cross-Linked Hydrogel Dressings Based on Triblock Copolymers Bearing Antifreezing, Antidrying, and Inherent Antibacterial Properties

Bacterial infections typically invade the living tissue of wounds, thereby aggravating the inflammatory response, delaying wound healing, or causing further complications. In this paper, the antibacterial hydrogel (PNVBA) with antifreezing and antidrying properties was prepared by a two-step method using N-isopropylacrylamide (NIPAM), 1-butyl-3-vinylimidazolium bromide (VBIMBr), and 3-acrylamidophenylboronic acid (AAPBA). PNVBA hydrogels exhibited a high adsorption capacity of 280 mg·g-1 for bovine serum albumin (BSA) and can adhere to the surface of different materials through ion-dipole or hydrogen-bonding interactions. Meanwhile, the PNVBA hydrogels exhibited high viscoelasticity and good adhesion after freezing at -20 °C or heating at 70 °C for 24 h with a sterilizing rate of up to 98% against multidrug-resistant (MDR) Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA). Moreover, a survival rate of up to 90% after incubation with L929 cells over 24 h was observed. Therefore, this inherent antibacterial hydrogel can be used as an excellent alternative material for wound dressings.

Low-adhesion and low-swelling hydrogel based on alginate and carbonated water to prevent temporary dilation of wound sites

Hydrogel-based wound dressings have been developed for rapid wound healing; however, their adhesive properties have not been adequately investigated. Excessive adhesion to the skin causes wound expansion and pain when hydrogels absorb exudates and swell at wound sites. Herein, we developed a low-adhesion and low-swelling hydrogel dressing using alginate, which is non-adhesive to cells and skin tissue, CaCO3, and carbonated water. The alginate/CaCO3 solution rapidly formed a hydrogel upon the addition of carbonated water, and the CO2 in the hydrogel diffused into the atmosphere, preventing acidification and obtaining a pH value suitable for wound healing. Remarkably, the skin adhesion and swelling of the hydrogel were 11.9- to 16.5-fold and 1.9-fold lower, respectively, than those of clinical low-adhesion hydrogel dressings. In vivo wound-healing tests in mice demonstrated its therapeutic efficacy, and the prepared hydrogel prevented temporary wound dilation during early healing. These results illustrate the importance of controlling skin adhesion and swelling in wound dressings and demonstrate the potential clinical applications of this wound-friendly hydrogel dressing.

Injectable thermogel incorporating reactive oxygen species scavenger and nitric oxide donor to accelerate the healing process of diabetic wounds

The healing of diabetic wounds is challenging due to redox imbalances. Herein, the thermogelling system AR-ACP hydrogel, with encapsulated biosafe nitric oxide (NO) donor L-arginine and resveratrol as an ROS scavenger, is established for sustainable wound therapy in the diabetic state. The innovated AR-ACP hydrogel dressings shows the sol-gel transition at 34 °C, allowing the hydrogel to fully cover wounds. The combination of L-arginine and resveratrol showed a prominent effect on anti-oxidative activity. The elimination of superoxide anions from the activated immune cells/oxidative cells by resveratrol maintained the NO-proangiogenic factors generated from L-arginine. Furthermore, the AR-ACP hydrogel endowed outstanding features such as haemocompatibility, non-skin irradiation as well as antibacterial activity. In the in vivo diabetic mice model, complete epidermal regeneration comparable to undamaged skin was observed with AR-ACP hydrogel. The synergy between L-arginine and resveratrol in the ACP hydrogel facilitated neovascularisation in the early stage, resulting in the higher balance in cellularity growth and collagen deposition in the dermal layer compared to control groups. Taken together, our findings demonstrate that the use of a customised ACP-based hydrogel, with the additional L-arginine and resveratrol, resulted in significant skin regeneration in the diabetic state.

Sprayable ciprofloxacin-loaded poloxamer hydrogels for wound infection treatment

Topical antimicrobial treatments for severe burns and chronic wounds provide effective treatment against infections, but cause pain and discomfort with application. This study aimed to develop an antimicrobial topical formulation comprising thermoreversible poloxamers (Pluronic F127 and F68) and a broad-spectrum antimicrobial agent (ciprofloxacin hydrochloride, CH), that could be sprayed to eliminate application pain while maintaining antimicrobial activity. Formulations were characterized to determine their sprayability under cold conditions, gelation temperature, final storage modulus at skin temperature, drug release profile, ex vivo permeation through impaired porcine skin, and inhibition against common bacterial pathogens that colonize wounds. All cold formulations were sprayable from simple hand-held, pump-action sprayers due to their low viscosity. Upon heating, 17 and 20% Pluronic F127 formulations produced hydrogels eight to ten degrees below skin temperature, independent of ciprofloxacin loading. Increasing concentrations of Pluronic F127 increased the final storage modulus and viscosity of the gels, while inclusion of Pluronic F68 reduced these properties, showing that hydrogel rheological properties at skin temperature can be tuned via choice of formulation. Drug release was directly correlated to the rheological properties, with stiffer gels resulting in a decrease in drug release rate. Overall, gels released about 65-90% of their load within 12 hours. Ex vivo skin permeation demonstrated that drug was well retained in impaired porcine skin, which is desired to continuously treat bacteria localized to the wound. A well-diffusion assay indicated that the hydrogels had greater bacterial inhibition against Pseudomonas aeruginosa, Escherichia coli, and two strains of Staphylococcus aureus when compared to commercial controls. Overall, the results show the potential of CH-loaded poloxamer formulations as suitable sprayable topical dressings to deliver antimicrobials directly to wounds.

Fabrication and evaluation of vitamin doped Zno/AgNPs nanocomposite based wheat gluten films: a promising findings for burn wound treatment

Burn wound treatment remains a significant issue in wound care management especially when multidrug resistant bacterial infection and accumulation are present. Delayed wound healing is mostly due to ineffectiveness of commercially available wound dressings that protects the wound but less efficient in healing perspective. Therefore, nano-based wound dressing might be efficient solution for wound healing management. The present study reports the fabrication and evaluation of zinc oxide (ZnO) or silver nanoparticles (Ag NPs) capped with vitamin A or E nanocomposite that were incorporated in wheat gluten (WG) films. The chemical structure, phase purity, and morphological features confirmed the successful coating of NPs by vitamins A and E and their interaction with WG during film casting. The maximum swelling response was observed by NPs vitamin composite WG films than control films while slow release of vitamins and NPs from films was observed up to 24 h. WG films either carrying ZnO or Ag NPs, and vitamin A or E demonstrated significant antioxidant and antibacterial potential. The NPs-vitamin composite loaded WG films showed wound contraction within 14 days during in vivo burn wound healing experiments on mice model. The rates of wound healing, re-epithelialization, collagen deposition with fibroblast regeneration, adipocytes, and hair follicle development were observed through visual and histopathological examination. The study reveals that vitamin A or E doped ZnO or Ag NPs fabricated in WG can be efficiently used against burn wounds due to their physiochemical and biological properties. Furthermore the biocompatible nature and biodegradable potential make the films more prone to mankind maneuver for initial protection and healing remedy.

pH-responsive scaffolds for tissue regeneration: In vivo performance

A myriad of pH-sensitive scaffolds has been reported in recent decades. Information on their behaviour in vitro under conditions that mimic the pH changes that occur during tissue regeneration is abundant. Differently, the in vivo demonstration of the advantages of pH-responsive systems in comparison with non-responders is more limited. The in vivo scenario is very complex and the intricate relationship between the host response, the overall pathological conditions of the patient, and the risk of colonization by microorganisms is very difficult to imitate in in vitro tests. This review aims to shed light on how the changes in pH between healthy and damaged states and also during the healing process have been exploited so far to develop polymer-based scaffolds that actively contribute in vivo to the healing process avoiding chronification. The main strategies so far tested to prepare pH-responsive scaffolds rely on (i) changes in ionization of natural polymers, ionizable monomers and clays, (ii) reversible cross-linkers, (iii) coatings, and (iv) production of CO2 gas. These strategies are analysed in detail in this review with the description of relevant examples of their performance on specific animal models. The versatility of the techniques used to prepare biocompatible and environment-friendly pH-responsive scaffolds that have been implemented in the last decade may pave the way for a successful translation to the clinic. STATEMENT OF SIGNIFICANCE: We report here on the most recent advances in pH-responsive polymer-based scaffolds that have been demonstrated in vivo to be suitable for wound and bone healing. pH is a critical variable in the tissue regeneration process, and small changes can speed up or completely stop the process. Although there is still a paucity of information on the performance in the complex in vivo environment, recently reported achievements using scaffolds endowed with pH-responsiveness through ionic natural polymers, ionizable monomers and clays, reversible cross-linkers, coatings, or formation of CO2 ensure a promising future towards clinical translation.

Applications of drug delivery systems, organic, and inorganic nanomaterials in wound healing

The skin is known to be the largest organ in the human body, while also being exposed to environmental elements. This indicates that skin is highly susceptible to physical infliction, as well as damage resulting from medical conditions such as obesity and diabetes. The wound management costs in hospitals and clinics are expected to rise globally over the coming years, which provides pressure for more wound healing aids readily available in the market. Recently, nanomaterials have been gaining traction for their potential applications in various fields, including wound healing. Here, we discuss various inorganic nanoparticles such as silver, titanium dioxide, copper oxide, cerium oxide, MXenes, PLGA, PEG, and silica nanoparticles with their respective roles in improving wound healing progression. In addition, organic nanomaterials for wound healing such as collagen, chitosan, curcumin, dendrimers, graphene and its derivative graphene oxide were also further discussed. Various forms of nanoparticle drug delivery systems like nanohydrogels, nanoliposomes, nanofilms, and nanoemulsions were discussed in their function to deliver therapeutic agents to wound sites in a controlled manner.

CD9 negatively regulates collective electrotaxis of the epidermal monolayer by controlling and coordinating the polarization of leader cells

Background

Endogenous electric fields (EFs) play an essential role in guiding the coordinated collective migration of epidermal cells to the wound centre during wound healing. Although polarization of leadercells is essential for collective migration, the signal mechanisms responsible for the EF-induced polarization of leader cells under electrotactic collective migration remain unclear. This study aims to determine how the leader cells are polarized and coordinated during EF-guided collective migration of epidermal cell sheets.

Methods

Collective migration of the human epidermal monolayer (human immortalized keratinocytes HaCaT) under EFs was observed via time-lapse microscopy. The involvement of tetraspanin-29 (CD9) in EF-induced fibrous actin (F-actin) polarization of leader cells as well as electrotactic migration of the epidermal monolayer was evaluated by genetic manipulation. Blocking, rescue and co-culture experiments were conducted to explore the downstream signalling of CD9.

Results

EFs guided the coordinated collective migration of the epithelial monolayer to the anode, with dynamic formation of pseudopodia in leader cells at the front edge of the monolayer along the direction of migration. F-actin polarization, as expected, played an essential role in pseudopod formation in leader cells under EFs. By confocal microscopy, we found that CD9 was colocalized with F-actin on the cell surface and was particularly downregulated in leader cells by EFs. Interestingly, genetic overexpression of CD9 abolished EF-induced F-actin polarization in leader cells as well as collective migration in the epidermal monolayer. Mechanistically, CD9 determined the polarization of F-actin in leader cells by downregulating a disintegrin and metalloprotease 17/heparin-binding epidermal growth factor-like growth factor/epidermal growth factor receptor (ADAM17/HB-EGF/EGFR) signalling. The abolished polarization of leader cells due to CD9 overexpression could be restored in a co-culture monolayer where normal cells and CD9-overexpressing cells were mixed; however, this restoration was eliminated again by the addition of the HB-EGF-neutralizing antibody.

Conclusion

CD9 functions as a key regulator in the EF-guided collective migration of the epidermal monolayer by controlling and coordinating the polarization of leader cells through ADAM17/HB-EGF/EGFR signalling.

Hydroxyapatite/hyperbranched polyitaconic acid/chitosan composite scaffold for bone tissue engineering

In this study, a promising modified composite scaffold (hydroxyapatite/hyperbranched polyitaconic acid/chitosan) was synthesized for bone tissue engineering. Novel hyperbranched polyitaconic acid was prepared through the polymerization of itaconic acid using reversible addition fragmentation chain transfer using a macro‐RAFT agent. The chemical structure of the prepared hyperbranched polyitaconic acid was characterized by FTIR and 1HNMR and was subsequently embedded into hydroxyapatite/chitosan composite. The obtained modified composite scaffold was evaluated by characterizing its porosity, mechanical properties, bioactivity and cytotoxicity. The results showed that the modified composite scaffold had higher mechanical strength (i.e., 0.56 ± 0.03 MPa) in comparison to chitosan/hydroxyapatite scaffold only (i.e., 0.31 ± 0.01 MPa) and also showed higher bioactivity. In addition, the modified composite scaffold (HAP/HBP‐RAFT‐PI/CS) showed anticancer properties and enhanced human skin fibroblasts proliferation.

Advanced Binary Guanosine and Guanosine 5'-Monophosphate Cell-Laden Hydrogels for Soft Tissue Reconstruction by 3D Bioprinting

Soft tissue defects or pathologies frequently necessitate the use of biomaterials that provide the volume required for subsequent vascularization and tissue formation as autrografts are not always a feasible alternative. Supramolecular hydrogels represent promising candidates because of their 3D structure, which resembles the native extracellular matrix, and their capacity to entrap and sustain living cells. Guanosine-based hydrogels have emerged as prime candidates in recent years since the nucleoside self-assembles into well-ordered structures like G-quadruplexes by coordinating K⁺ ions and π-π stacking, ultimately forming an extensive nanofibrillar network. However, such compositions were frequently inappropriate for 3D printing due to material spreading and low shape stability over time. Thus, the present work aimed to develop a binary cell-laden hydrogel capable of ensuring cell survival while providing enough stability to ensure scaffold biointegration during soft tissue reconstruction. For that purpose, a binary hydrogel made of guanosine and guanosine 5'-monophosphate was optimized, rat mesenchymal stem cells were entrapped, and the composition was bioprinted. To further increase stability, the printed structure was coated with hyperbranched polyethylenimine. Scanning electron microscopic studies demonstrated an extensive nanofibrillar network, indicating excellent G-quadruplex formation, and rheological analysis confirmed good printing and thixotropic qualities. Additionally, diffusion tests using fluorescein isothiocyanate labeled-dextran (70, 500, and 2000 kDa) showed that nutrients of various molecular weights may diffuse through the hydrogel scaffold. Finally, cells were evenly distributed throughout the printed scaffold, cell survival was 85% after 21 days, and lipid droplet formation was observed after 7 days under adipogenic conditions, indicating successful differentiation and proper cell functioning. To conclude, such hydrogels may enable the 3D bioprinting of customized scaffolds perfectly matching the respective soft tissue defect, thereby potentially improving the outcome of the tissue reconstruction intervention.

Magnesium (Mg2 +), Strontium (Sr2 +), and Zinc (Zn2 +) Co-substituted Bone Cements Based on Nano-hydroxyapatite/Monetite for Bone Regeneration

New bone cement type that combines Sr2 + /Mg2 + or Sr2 + /Zn2 + co-substituted nano-hydroxyapatite (n-HAs) with calcium phosphate dibasic and chitosan/gelatin polymers was developed to increase adhesion and cellular response. The cements were physicochemically described and tested in vitro using cell cultures. All cements exhibited quite hydrophilic and had high washout resistance. Cement releases Ca2 + , Mg2 + , Sr2 + , and Zn2 + in concentrations that are suitable for osteoblast proliferation and development. All of the cements stimulated cell proliferation in fibroblasts, endothelial cells, and osteoblasts, were non-cytotoxic, and produced apatite. Cements containing co-substituted n-HAs had excellent cytocompatibility, which improved osteoblast adhesion and cell proliferation. These cements had osteoinductive potential, stimulating extracellular matrix (ECM) mineralization and differentiation of MC3T3-E1 cells by increasing ALP and NO production. The ions Ca2 + , Mg2 + , Zn2 + , and Sr2 + appear to cooperate in promoting osteoblast function. The C3 cement (HA-SrMg5%), which was made up of n-HA co-substituted with 5 mol% Sr and 5 mol% Mg, showed exceptional osteoinductive capacity in terms of bone regeneration, indicating that this new bone cement could be a promising material for bone replacement.

Breakthrough treatments for accelerated wound healing

Skin injuries across the body continue to disrupt everyday life for millions of patients and result in prolonged hospital stays, infection, and death. Advances in wound healing devices have improved clinical practice but have mainly focused on treating macroscale healing versus underlying microscale pathophysiology. Consensus is lacking on optimal treatment strategies using a spectrum of wound healing products, which has motivated the design of new therapies. We summarize advances in the development of novel drug, biologic products, and biomaterial therapies for wound healing for marketed therapies and those in clinical trials. We also share perspectives for successful and accelerated translation of novel integrated therapies for wound healing.

Wound pH and temperature as predictors of healing: an observational study

OBJECTIVE

The aim of this study was to measure wound pH, wound temperature and wound size together to gain further understanding of their impact as predictors of wound healing outcomes.

METHOD

This study employed a quantitative non-comparative, prospective, descriptive observational design. Participants with both acute and hard-to-heal (chronic) wounds were observed weekly for four weeks. Wound pH was measured using pH indicator strips, wound temperature was measured using an infrared camera and wound size was measured using the ruler method.

RESULTS

Most of the 97 participants (65%, n=63) were male; participant's ages ranged between 18 and 77 years (mean: 42±17.10. Most of the wounds observed were surgical 60%, (n=58) and 72% (n=70) of the wounds were classified as acute, with 28% (n=27) classified as hard-to-heal wounds. At baseline, there was no significant difference in pH between acute and hard-to-heal wounds; overall the mean pH was 8.34±0.32, mean temperature was 32.86±1.78°C) and mean wound area was 910.50±1132.30mm2. In week 4, mean pH was 7.71±1.11, mean temperature was 31.90±1.76°C and mean wound area was 339.90±511.70mm2. Over the study follow-up period, wound pH ranged from 5-9, from week 1 to week 4, mean pH reduced by 0.63 units from 8.34 to 7.71. Furthermore, there was a mean 3% reduction in wound temperature and a mean 62% reduction in wound size.

CONCLUSION

The study demonstrated that a reduction in pH and temperature was associated with increased wound healing as evidenced by a corresponding reduction in wound size. Thus, measuring pH and temperature in clinical practice may provide clinically meaningful data pertaining to wound status.

Controlling collagen gelation pH to enhance biochemical, structural, and biomechanical properties of tissue-engineered menisci

Collagen-based hydrogels have been widely used in biomedical applications due to their biocompatibility. Enhancing mechanical properties of collagen gels remains challenging while maintaining biocompatibility. Here, we demonstrate that gelation pH has profound effects on cellular activity, collagen fibril structure, and mechanical properties of the fibrochondrocyte-seeded collagen gels in both short- and long-terms. Acidic and basic gelation pH, below pH 7.0 and above 8.5, resulted in dramatic cell death. Gelation pH ranging from 7.0 to 8.5 showed a relatively high cell viability. Furthermore, physiologic gelation (pH 7.5) showed the greatest collagen deposition while glycosaminoglycan deposition appeared independent of gelation pH. Scanning electron microscopy showed that neutral and physiologic gelation pH, 7.0 and 7.5, exhibited well-aligned collagen fibril structure on day 0 and enhanced collagen fibril structure with laterally joined fibrils on day 30. However, basic pH, 8.0 and 8.5, displayed a densely packed collagen fibril structure on day 0, which was also persistent on day 30. Initial equilibrium modulus increased with increasing gelation pH. Notably, after 30 days of culture, gelation pH of 7.5 and 8.0 showed the highest equilibrium modulus, reaching 150 -160 kPa. While controlling gelation pH is simply achieved compared with other strategies to improve mechanical properties, its influences on biochemical and biomechanical properties of the collagen gel are long-lasting. As such, gelation pH is a useful means to modulate both biochemical and biomechanical properties of the collagen-based hydrogels and can be utilized for diverse types of tissue engineering due to its simple application.

An injectable porous bioactive magnesium phosphate bone-cement foamed with calcium carbonate and citric acid for periodontal bone regeneration

Magnesium phosphate cement (MPC) has been evaluated as a novel bone substitute owing to its favorable biocompatibility, plasticity, and osteogenic potential. However, the low porosity of MPC prevents growth factors and osteoblasts from fully growing into the material, thereby limiting its clinical use. In this study, different concentrations (0-5%) of calcium carbonate and citric acid (CA) were used as foaming agents to prepare porous MPC. The MPC containing 3% CaCO₃/CA exhibited the best physicochemical properties, including greater porosity, improved injectability, extended setting time, and decreased hydration temperature. The proliferation and adhesion of cells on 3%CaCO₃/CA-MPC were higher than those on MPC alone. To explore its osteogenesis in vivo, 3% CaCO₃/CA-MPC and Bio-Oss® bone powder were implanted into periodontal bone defects in rats for 4 weeks and 12 weeks, respectively. Micro-CT and histological analysis demonstrated the improved bone regeneration of 3%CaCO₃/CA-MPC compared to the blank group (P < 0.05); it had slightly lower bone regeneration than the Bio-Oss® group but no statistical difference. The results indicated that porous MPC foamed with calcium carbonate and CA improved its physicochemical properties and enhanced its biocompatibility, making it a promising material for bone regeneration.

Nanoparticle protein corona: from structure and function to therapeutic targeting

Nanoparticle (NP)-based therapeutics have ushered in a new era in translational medicine. However, despite the clinical success of NP technology, it is not well-understood how NPs fundamentally change in biological environments. When introduced into physiological fluids, NPs are coated by proteins, forming a protein corona (PC). The PC has the potential to endow NPs with a new identity and alter their bioactivity, stability, and destination. Additionally, the conformation of proteins is sensitive to their physical and chemical surroundings. Therefore, biological factors and protein-NP-interactions can induce changes in the conformation and orientation of proteins in vivo. Since the function of a protein is closely connected to its folded structure, slight differences in the surrounding environment as well as the surface characteristics of the NP materials may cause proteins to lose or gain a function. As a result, this can alter the downstream functionality of the NPs. This review introduces the main biological factors affecting the conformation of proteins associated with the PC. Then, four types of NPs with extensive utility in biomedical applications are described in greater detail, focusing on the conformation and orientation of adsorbed proteins. This is followed by a discussion on the instances in which the conformation of adsorbed proteins can be leveraged for therapeutic purposes, such as controlling protein conformation in assembled matrices in tissue, as well as controlling the PC conformation for modulating immune responses. The review concludes with a perspective on the remaining challenges and unexplored areas at the interface of PC and NP research.

Polydopamine Incorporation Enhances Cell Differentiation and Antibacterial Properties of 3D-Printed Guanosine-Borate Hydrogels for Functional Tissue Regeneration

Tissue engineering focuses on the development of materials as biosubstitutes that can be used to regenerate, repair, or replace damaged tissues. Alongside this, 3D printing has emerged as a promising technique for producing implants tailored to specific defects, which in turn increased the demand for new inks and bioinks. Especially supramolecular hydrogels based on nucleosides such as guanosine have gained increasing attention due to their biocompatibility, good mechanical characteristics, tunable and reversible properties, and intrinsic self-healing capabilities. However, most existing formulations exhibit insufficient stability, biological activity, or printability. To address these limitations, we incorporated polydopamine (PDA) into guanosine-borate (GB) hydrogels and developed a PGB hydrogel with maximal PDA incorporation and good thixotropic and printability qualities. The resulting PGB hydrogels exhibited a well-defined nanofibrillar network, and we found that PDA incorporation increased the hydrogel's osteogenic activity while having no negative effect on mammalian cell survival or migration. In contrast, antimicrobial activity was observed against the Gram-positive bacteria Staphylococcus aureus and Staphylococcus epidermidis. Thus, our findings suggest that our PGB hydrogel represents a significantly improved candidate as a 3D-printed scaffold capable of sustaining living cells, which may be further functionalized by incorporating other bioactive molecules for enhanced tissue integration.

A self-gelling starch-based sponge for hemostasis

Uncontrolled bleeding remains one of the direct causes of high mortality. There is an urgent need for developing emergency hemostats capable of coping with uncontrolled bleeding. The commercial starch-based hemostatic powder (PerClot®) requires compression during application, which limits its application in hemostasis of irregular and non-compressed wounds. Herein, a boronic acid-modified thiol starch sponge (St-SP sponge) with self-gelling properties was developed for hemorrhage control. The results show that the St-SP sponge could quickly absorb blood, self-gel and self-heal to seal the bleeding sites. In addition, the St-SP sponge can rapidly initiate the coagulation cascade and promote the adhesion and aggregation of erythrocytes and platelets. The St-SP sponge exhibited significantly improved in vitro and in vivo hemostatic abilities as compared with PerClot. Notably, the St-SP sponge attained complete hemostasis without any compression in 61.5 s and made a great difference compared to PerClot (169 s) for the irregular wound constructed on the rabbit liver. In addition, the St-SP sponge had good hemocompatibility and cytocompatibility. It turns out that the newly developed St-SP sponge is a promising material for first-aid hemostasis of irregular and non-compressed wounds.

Fabrication and in vitro characterization of zinc oxide nanoparticles and hyaluronic acid-containing carboxymethylcellulose gel for wound healing application

Chronic wounds, such as burns and diabetic ulcers, are complex wounds sustained by the skin that require life-long rehabilitation and have the potential to deteriorate and get infected. The number of patients with this ailment has been steadily increasing. This illness demands the use of new dressings with the best capabilities for managing wound healing. This study created an gel with carboxymethylcellulose (CMC), hyaluronic acid (HA), and zinc oxide nanoparticles (ZnO NPs). According to the findings, the manufacturing technique with a 1:4 ratio of HA and CMC gel had the best viscosity. Additionally, varying concentrations of zinc oxide nanoparticles (ZnO NPs) were added to the formula. Variations included 0.05, 0.125, 0.5, 1.0, 3.0, 5.0, and 10% by weight. In order to find the ideal dose and formulation, physical properties, an anti-bacterial test, and a cell migration assay were carried out. The samples with concentration of 0.5, 1.0, 3.0, 5.0 and 10% w/v showed ability to kill gram-positive and gram-negative bacteria. Wound healing experiments showed that cells proliferated for HA/CMC/ZnO gel with a weight-to-volume ratio of 0.05% and 1.0% w/v. In conclusion, according to all (physical and biological) characterization, the HA/CMC/ZnO gel with a weight-to-volume ratio of 1.0% w/v was found to have a considerable standard for wound-healing materials, demonstrating a promising effect against bacteria.

pH and its applications in targeted drug delivery

Physiologic pH is vital for the normal functioning of tissues and varies in different parts of the body. The varying pH of the body has been exploited to design pH-sensitive smart oral, transdermal and vaginal drug delivery systems (DDS). The DDS demonstrated promising results in hard-to-treat diseases such as cancer and Helicobacter pylori infection. In some cases, a change in pH of tissues or body fluids has also been employed as a useful diagnostic biomarker. This paper aims to comprehensively review the development and applications of pH-sensitive DDS as well as recent advances in the field.

Engineering nano-drug biointerface to overcome biological barriers toward precision drug delivery

The rapid advancement of nanomedicine and nanoparticle (NP) materials presents novel solutions potentially capable of revolutionizing health care by improving efficacy, bioavailability, drug targeting, and safety. NPs are intriguing when considering medical applications because of their essential and unique qualities, including a significantly higher surface to mass ratio, quantum properties, and the potential to adsorb and transport drugs and other compounds. However, NPs must overcome or navigate several biological barriers of the human body to successfully deliver drugs at precise locations. Engineering the drug carrier biointerface can help overcome the main biological barriers and optimize the drug delivery in a more personalized manner. This review discusses the significant heterogeneous biological delivery barriers and how biointerface engineering can promote drug carriers to prevail over hurdles and navigate in a more personalized manner, thus ushering in the era of Precision Medicine. We also summarize the nanomedicines' current advantages and disadvantages in drug administration, from natural/synthetic sources to clinical applications. Additionally, we explore the innovative NP designs used in both non-personalized and customized applications as well as how they can attain a precise therapeutic strategy.

Simple Preparation of Injectable Hydrogels with Phase-Separated Structures That Can Encapsulate Live Cells

Injectable hydrogels are biomaterials that can be administered minimally invasively in liquid form and are considered promising artificial extracellular matrix (ECM) materials. However, ordinary injectable hydrogels are synthesized from water-soluble molecules to ensure injectability, resulting in non-phase-separated structures, making them structurally different from natural ECMs with phase-separated insoluble structural proteins, such as collagen and elastin. Here, we propose a simple material design approach to impart phase-separated structures to injectable hydrogels by adding inorganic salts. Injecting a gelling solution of mutually cross-linkable tetra-arm poly(ethylene glycol)s with potassium sulfate at optimal concentrations results in the formation of a hydrogel with phase-separated structures in situ. These phase-separated structures provide up to an 8-fold increase in fracture toughness while allowing the encapsulation of live mouse chondrogenic cells without compromising their proliferative activity. Our findings highlight that the concentration of inorganic salts is an important design parameter in injectable hydrogels for artificial ECMs.

Honey: An Advanced Antimicrobial and Wound Healing Biomaterial for Tissue Engineering Applications

Honey was used in traditional medicine to treat wounds until the advent of modern medicine. The rising global antibiotic resistance has forced the development of novel therapies as alternatives to combat infections. Consequently, honey is experiencing a resurgence in evaluation for antimicrobial and wound healing applications. A range of both Gram-positive and Gram-negative bacteria, including antibiotic-resistant strains and biofilms, are inhibited by honey. Furthermore, susceptibility to antibiotics can be restored when used synergistically with honey. Honey’s antimicrobial activity also includes antifungal and antiviral properties, and in most varieties of honey, its activity is attributed to the enzymatic generation of hydrogen peroxide, a reactive oxygen species. Non-peroxide factors include low water activity, acidity, phenolic content, defensin-1, and methylglyoxal (Leptospermum honeys). Honey has also been widely explored as a tissue-regenerative agent. It can contribute to all stages of wound healing, and thus has been used in direct application and in dressings. The difficulty of the sustained delivery of honey’s active ingredients to the wound site has driven the development of tissue engineering approaches (e.g., electrospinning and hydrogels). This review presents the most in-depth and up-to-date comprehensive overview of honey’s antimicrobial and wound healing properties, commercial and medical uses, and its growing experimental use in tissue-engineered scaffolds.

Micro-Gel Ensembles for Accelerated Healing of Chronic Wound via pH Regulation

The pH value in the wound milieu plays a key role in cellular processes and cell cycle processes involved in the process of wound healing. Here, a microfluidic assembly technique is employed to fabricate micro-gel ensembles that can precisely tune the pH value of wound surface and accelerate wound healing. The micro-gel ensembles consist of poly (hydroxypropyl acrylate-co-acrylic acid)-magnesium ions (poly-(HPA-co-AA)-Mg²⁺ ) gel and carboxymethyl chitosan (CMCS) gel, which can release and absorb hydrogen ion (H⁺ ) separately at different stages of healing in response to the evolution of wound microenvironment. By regulating the wound pH to affect the proliferation and migration of cell on the wound and the activity of various biological factors in the wound, the physiological processes are greatly facilitated which results in much accelerated healing of chronic wound. This work presents an effective strategy in designing wound healing materials with vast potentials for chronic wound management.

Characterization of silver diamine fluoride cytotoxicity using microfluidic tooth-on-a-chip and gingival equivalents

OBJECTIVE

This study aims to characterize the cytotoxicity potential of silver diamine fluoride (SDF) on dental pulp stem cells (DPSC) and gingival equivalents.

METHODS

DPSC cultured on 96-well plates was exposed directly to SDF (0.0001-0.01%) and cell viability (IC₅₀) quantified. Effect of SDF on DPSC viability under flow (with dentin barrier) conditions was evaluated using a custom-designed microfluidic "tooth-on-a-chip". Permeability of dentin discs (0.5-1.5 mm thickness) was evaluated using lucifer yellow permeation assay. Dentin discs were treated with 38% SDF (up to 3 h), and cell viability (live/dead assay) of the DPSC cultured in the inlet (unexposed) and outlet (exposed) regions of the pulp channel was evaluated. To assess the mucosal corrosion potential, gingival equivalents were treated with 38% SDF for 3 or 60 min (OECD test guideline 431) and characterized by MTT assay and histomorphometric analysis.

RESULTS

DPSC exposed directly to SDF showed a dose-dependent reduction in cell viability (IC₅₀: 0.001%). Inlet channels (internal control) of the tooth-on-a-chip exposed to PBS and SDF-exposed dentin discs showed> 85% DPSC viability. In contrast, the outlet channels of SDF-exposed dentin discs showed a decreased viability of< 31% and 0% (1.5 and ≤1.0 mm thick dentin disc, respectively) (p < 0.01). The gingiva equivalents treated with SDF for 3 and 60 min demonstrated decreased epithelial integrity, loss of intercellular cohesion and corneal layer detachment with significant reduction in intact epithelial thickness (p < 0.05).

SIGNIFICANCE

SDF penetrated the dentin (≤1 mm thick) inducing significant death of the pulp cells. SDF also disrupted gingival epithelial integrity resulting in mucosal corrosion.

Biopolymeric composite hydrogel loaded with silver NPs and epigallocatechin gallate (EGCG) effectively manages ROS for rapid wound healing in type II diabetic wounds

Delayed wound healing in patients having type-II diabetes mellitus (T2DM) often results in a high rate of amputation. We report an innovative Guar Gum-based macroporous hydrogel (HG) infused with an antibacterial agent (Ag NPs), and antioxidant, epigallocatechin gallate (EGCG) to address rapid wound healing and interestingly could inhibit the associated pathophysical bone infection in a high-fat-diet-induced T2DM C57BL/6 mice model. The HG-Ag-EGCG elicits scar-free wound healing in subcutaneous wounds and histopathological evidence confirmed HG-Ag-EGCG hydrogel patch elicits better wound healing through enhanced cell proliferation, mature connecting tissue fiber formation, minimum void spaces formation, and better re-epithelialization when compared with a market available hydrogel patch material (Luofucon®). Supportive of the in vivo outcomes, in vitro experiments delineated better-wound closure due to improved management of ROS by the HG-Ag-EGCG. Additionally, a favorable non-toxicity outcome assessed through both in vitro and in vivo conditions confirmed its potential applicability in clinical wound care management.

Calcium Phosphate/Hyaluronic Acid Composite Hydrogels for Local Antiosteoporotic Drug Delivery

Despite the bone ability of self-regeneration, large bone defects require surgical intervention. Likewise, when it comes to osteoporotic bone fractures, new approaches should be considered a supportive mechanism for the surgery. In recent years, more and more attention has been attracted to advanced drug delivery systems for local osteoporosis treatment, combining appropriate biomaterials with antiosteoporotic drugs, allowing simultaneously to regenerate the bone and locally treat the osteoporosis. Within the current research, hyaluronic acid/strontium ranelate (HA/SrRan), HA/calcium phosphate nanoparticles (HA/CaP NPs), and HA/CaP NPs/SrRan hydrogels were prepared. The effect of CaP and SrRan presence in the composites on the swelling behavior, gel fraction, molecular structure, microstructure, and SrRan and Sr2+ release, as well as in vitro cell viability was evaluated. Obtained results revealed that the route of CaP nanoparticle incorporation into the HA matrix had a significant effect on the hydrogel gel fraction, rheological properties, swelling behavior, and microstructure. Nevertheless, it had a negligible effect on the release kinetics of SrRan and Sr2+. The highest cell (3T3) viability (&gt;80%) was observed for HA hydrogels, with and without SrRan. Moreover, the positive effect of SrRan on 3T3 cells was also demonstrated, showing a significant increase (up to 50%) in cell viability if the used concentrations of SrRan were in the range of 0.05–0.2 μg/ml.

Keratin-based wound dressings: From waste to wealth

Keratin is a natural protein with a high content of cysteine residues (7-13%) and is widely found in hair, wool, horns, hooves, and nails. Keratin possesses abundant cell-binding motifs such as leucine-aspartate-valine (LDV), glutamate-aspartate-serine (EDS), and arginine-glycine-aspartate (RGD), which benefit cell attachment and proliferation. It has been confirmed that keratin plays important roles in every stage of wound healing, including hemostasis, inflammation, proliferation, and remodeling, making keratin-based materials good candidates for wound dressings. In combination with synthetic and natural polymers, keratin-based wound dressings in the forms of films, hydrogels, and nanofibers can be achieved with improved mechanical properties. This review focuses on the recent development of keratin-based wound dressings. Firstly, the physicochemical and biological properties of keratin, are systematically discussed. Secondly, the role of keratin in wound healing is proposed. Thirdly, the applications of keratin-based wound dressings are summarized, in terms of the forms and functionalization. Finally, the current challenges and future development of keratin-based wound dressings are presented.

In Vitro Wound Healing Properties of Novel Acidic Treatment Regimen in Enhancing Metabolic Activity and Migration of Skin Cells

Strategies that alter the pH of wounds to improve healing outcomes are an emerging area of interest. Currently, there is limited understanding of the effect of hydrogen (H⁺) on the functionality of skin cells during proliferation and migration, highlighting the need for research to determine the effect of pH during wound healing. This study aimed to determine the effect of acidification on the metabolic activity and migration of human immortalized keratinocytes (HaCaT) and human foreskin fibroblasts (HFF). In vitro models were used with phosphoric and citric acid buffers at a pH range between 3 and 7. Our results showed that cells were more viable in buffers with low rather than high ionic strength. A time-dependent effect of the acidification treatment was also observed with cell metabolic activity varying with treatment duration and frequency. Our results showed that a 24 h treatment and subsequent resting phase significantly improved cell proliferation and migration. This in vitro study is the first to establish a correlation between the role of acidic pH, molarity and treatment regimen in cellular activity. Our data demonstrated a positive effect of acidic pH on cell metabolic activity and migration rate, suggesting a clinical potential in indications such as wound healing.

Synthesis and characterization of stimuli-responsive hydrogels: evaluation of external stimuli influence on L929 fibroblast viability

In this study, poly(2-hydroxyethyl methacrylate) [p(HEMA)] based hydrogels responsive to the pH, temperature and magnetic field were synthesized. The surface properties of p(HEMA) were improved by designing the stimuli-responsive hydrogels made of MAGA, NIPAAm and methacrylate-decorated magnetite nanoparticles as a function of pH-, thermo- and magnetic responsive cell culture surfaces. These materials were then modified an abundant extracellular matrix component, type I collagen, which has been considered as a biorecognition element to increase the applicability of hydrogels to cell viability. Based on results from scanning electron microscopy (SEM) and thermal gravimetric analysis (TGA), stimuli-responsive hydrogel demonstrated improved non-porous structures and thermal stability with a high degree of cross-linking. Mechanical analyses of the hydrogels also showed that stimuli-responsive hydrogels are more elastomeric due to the polymeric chains and heterogeneous amorphous segments compared to plain hydrogels. Furthermore, surface modification of hydrogels with collagen provided better biocompatibility, which was confirmed with L929 fibroblast cell adhesion. Produced stimuli-responsive hydrogels modulated cellular viability by changing pH and magnetic field.

WPI Hydrogels with a Prolonged Drug-Release Profile for Antimicrobial Therapy

Infectious sequelae caused by surgery are a significant problem in modern medicine due to their reduction of therapeutic effectiveness and the patients’ quality of life.Recently, new methods of local antimicrobial prophylaxis of postoperative sequelae have been actively developed. They allow high local concentrations of drugs to be achieved, increasing the antibiotic therapy’s effectiveness while reducing its side effects. We have developed and characterized antimicrobial hydrogels based on an inexpensive and biocompatible natural substance from the dairy industry—whey protein isolate—as matrices for drug delivery. The release of cefazolin from the pores of hydrogel structures directly depends on the amount of the loaded drug and occurs in a prolonged manner for three days. Simultaneously with the antibiotic release, hydrogel swelling and partial degradation occurs. The WPI hydrogels absorb solvent, doubling in size in three days and retaining cefazolin throughout the duration of the experiment. The antimicrobial activity of cefazolin-loaded WPI hydrogels against Staphylococcus aureus growth is prolonged in comparison to that of the free cefazolin. The overall cytotoxic effect of cefazolin-containing WPI hydrogels is lower than that of free antibiotics. Thus, our work shows that antimicrobial WPI hydrogels are suitable candidates for local antibiotic therapy of infectious surgical sequelae.

Cellulose-Based Nanomaterials Advance Biomedicine: A Review

There are various biomaterials, but none fulfills all requirements. Cellulose biopolymers have advanced biomedicine to satisfy high market demand and circumvent many ecological concerns. This review aims to present an overview of cellulose knowledge and technical biomedical applications such as antibacterial agents, antifouling, wound healing, drug delivery, tissue engineering, and bone regeneration. It includes an extensive bibliography of recent research findings from fundamental and applied investigations. Cellulose-based materials are tailorable to obtain suitable chemical, mechanical, and physical properties required for biomedical applications. The chemical structure of cellulose allows modifications and simple conjugation with several materials, including nanoparticles, without tedious efforts. They render the applications cheap, biocompatible, biodegradable, and easy to shape and process.

The Promise of Nanotechnology in Personalized Medicine

Both personalized medicine and nanomedicine are new to medical practice. Nanomedicine is an application of the advances of nanotechnology in medicine and is being integrated into diagnostic and therapeutic tools to manage an array of medical conditions. On the other hand, personalized medicine, which is also referred to as precision medicine, is a novel concept that aims to individualize/customize therapeutic management based on the personal attributes of the patient to overcome blanket treatment that is only efficient in a subset of patients, leaving others with either ineffective treatment or treatment that results in significant toxicity. Novel nanomedicines have been employed in the treatment of several diseases, which can be adapted to each patient-specific case according to their genetic profiles. In this review, we discuss both areas and the intersection between the two emerging scientific domains. The review focuses on the current situation in personalized medicine, the advantages that can be offered by nanomedicine to personalized medicine, and the application of nanoconstructs in the diagnosis of genetic variability that can identify the right drug for the right patient. Finally, we touch upon the challenges in both fields towards the translation of nano-personalized medicine.

Injectable Self-Crosslinkable Thiolated Hyaluronic Acid for Stem Cell Therapy of Atopic Dermatitis

Stem cell therapies offer great promise in regenerative medicine to reinstate the normal function of diseased tissue, thereby avoiding the need for replacement. In stem cell therapies, damaged cells are replaced or restored by regulating inflammation and the immune system. However, the low survival rate and local retention of transplanted cells pose a significant challenge. In this study, injectable self-crosslinkable hydrogels using thiol-functionalized hyaluronic acid (HA-SH) were developed to improve the efficacy of mesenchymal stem cells (MSCs) for treating atopic dermatitis (AD)-related inflammatory lesions. The gelation kinetics and mechanical properties of HA-SH hydrogels were easily tuned by varying the concentration of the polymer in the precursor solution before injection. The MSC-laden HA-SH hydrogels exhibited high cell viability (>80%) for 1 week and good in vivo biocompatibility after implantation beneath the mouse skin. Moreover, the MSC-laden HA-SH hydrogel showed increased expression of anti-inflammatory cytokines, which can alleviate the immune response. In an AD animal model, a reduction in epidermal thickness and mast cell infiltration was achieved by applying a self-crosslinkable HA-SH solution including MSCs. This HA-based injectable hydrogel represents a potential carrier of stem cells, and its strong immunomodulation capabilities can be utilized for treating inflammation-related diseases.

Ag-Contained Superabsorbent Curdlan–Chitosan Foams for Healing Wounds in a Type-2 Diabetic Mice Model

This study focused on the synthesis and characterization of pure curdlan–chitosan foams (CUR/CS), as well as foams containing Ag nanoparticles (CUR/CS/Ag), and their effect on the skin repair of diabetic mice (II type). The layer of antibacterial superabsorbent foam provides good oxygenation, prevents bacterial infection, and absorbs exudate, forming a soft gel (moist environment). These foams were prepared from a mixture of hydrolyzed curdlan and chitosan by lyophilization. To enhance the antibacterial properties, an AgNO₃ solution was added to the curdlan/chitosan mixture during the polymerization and was then reduced by UV irradiation. The membranes were further investigated for their structure and composition using optical microscopy, scanning electron microscopy, energy-dispersive spectroscopy, FT-IR spectroscopy, and XPS analysis and modeling. In vivo tests demonstrated that CUR/CS/Ag significantly boosted the regeneration process compared with pure CUR/CS and the untreated control.