Polyvinylpyrrolidone/hyaluronic acid-based bilayer constructs for sequential delivery of cutaneous antiseptic and antibiotic

Recent advances in the development of chitosan/hyaluronic acid-based hybrid materials for skin protection, regeneration, and healing: A review

Biomaterials play vital roles in regenerative medicine, specifically in tissue engineering applications. They promote angiogenesis and facilitate tissue creation and repair. The most difficult aspect of this field is acquiring smart biomaterials that possess qualities and functions that either surpass or are on par with those of synthetic products. The biocompatibility, biodegradability, film-forming capacity, and hydrophilic nature of the non-sulfated glycosaminoglycans (GAGs) (hyaluronic acid (HA) and chitosan (CS)) have attracted significant attention. In addition, CS and HA possess remarkable inherent biological capabilities, such as antimicrobial, antioxidant, and anti-inflammatory properties. This review provides a comprehensive overview of the recent progress made in designing and fabricating CS/HA-based hybrid materials for dermatology applications. Various formulations utilizing CS/HA have been developed, including hydrogels, microspheres, films, foams, membranes, and nanoparticles, based on the fabrication protocol (physical or chemical). Each formulation aims to enhance the materials' remarkable biological properties while also addressing their limited stability in water and mechanical strength. Additionally, this review gave a thorough outline of future suggestions for enhancing the mechanical strength of CS/HA wound dressings, along with methods to include biomolecules to make them more useful in skin biomedicine applications.

Exploring Cationic Guar Gum: Innovative Hydrogels and Films for Enhanced Wound Healing

Background/Objectives: This study developed and characterized hydrogels (HG-CGG) and films (F-CGG) based on cationic guar gum (CGG) for application in wound healing. Methods: HG-CGG (2% w/v) was prepared by gum thickening and evaluated for pH, stability, spreadability, and viscosity. F-CGG was obtained using an aqueous dispersion of CGG (6% w/v) and the solvent casting method. F-CGG was characterized for thickness, weight uniformity, morphology, mechanical properties, hydrophilicity, and swelling potential. Both formulations were evaluated for bioadhesive potential on intact and injured porcine skin, as well as antioxidant activity. F-CGG was further studied for biocompatibility using hemolysis and cell viability assays (L929 fibroblasts), and its wound-healing potential by the scratch assay. Results: HG-CGG showed adequate viscosity and spreadability profiles for wound coverage, but its bioadhesive strength was reduced on injured skin. In contrast, F-CGG maintained consistent bioadhesive strength regardless of skin condition (6554.14 ± 540.57 dyne/cm2 on injured skin), presenting appropriate mechanical properties (flexible, transparent, thin, and resistant) and a high swelling capacity (2032 ± 211% after 6 h). F-CGG demonstrated superior antioxidant potential compared to HG-CGG (20.50 mg/mL ABTS+ radical scavenging activity), in addition to exhibiting low hemolytic potential and no cytotoxicity to fibroblasts. F-CGG promoted the proliferation of L929 cells in vitro, supporting wound healing. Conclusions: Therefore, CGG proved to be a promising material for developing formulations with properties suitable for cutaneous use. F-CGG combines bioadhesion, antioxidant activity, biocompatibility, cell proliferation, and potential wound healing, making it promising for advanced wound treatment.

Quercetin encapsulated polycaprolactone-polyvinylpyrrolidone electrospun membranes as a delivery system for wound healing applications

The present work focuses on the production of electrospun membranes based on Poly(ε-caprolactone) (PCL) and Polyvinylpyrrolidone (PVP) for the topical release of Quercetin (Q). Membranes were prepared at 0.5, 1.0, 3.0, 7.0 and 15 % wt of Quercetin and studied from a morphological, physical, and biological point of view. The scanning electron microscopy (SEM) evidences micrometric dimensions of the fibres with a good dispersion of the functional molecule. The retention degree of liquids was evaluated by testing four different liquid media while the radical scavenging activity of Quercetin-loaded membranes was evaluated through DPPH analysis. The release kinetics of Quercetin highlights the presence of an initial burst followed by slower release up to attaining an equilibrium state, after roughly 50 h, showing the possibility of a fine-tuning of drug release. Diffusion coefficients were then evaluated by using Fick's law. Finally, to verify the actual biocompatibility of the systems produced and the possible application in the repair of tissue injury, the biological activity of Quercetin released from drug-loaded membranes was analysed in an immortalized human keratinocyte cell line HaCaT by a wound healing assay. So, the reported preliminary data confirm the possibility of applying the electrospun Quercetin-loaded PCL-PVP membranes for wound healing applications.

Rapid formed temperature-sensitive hydrogel for the multi-effective wound healing of deep second-degree burn with shikonin based scar prevention

Burns are a significant public health issue worldwide, resulting in prolonged hospitalization, disfigurement, disability and, in severe cases, death. Among them, deep second-degree burns are often accompanied by bacterial infections, insufficient blood flow, excessive skin fibroblasts proliferation and collagen deposition, all of which contribute to poor wound healing and scarring following recovery. In this study, SNP/MCNs-SKN-chitosan-β-glycerophosphate hydrogel (MSSH), a hydrogel composed of a temperature-sensitive chitosan-β-glycerophosphate hydrogel matrix (CGH), mesoporous carbon nanospheres (MCNs), nitric oxide (NO) donor sodium nitroprusside (SNP) and anti-scarring substance shikonin (SKN), is intended for use as a biomedical material. In vitro tests have revealed that MSSH has broad-spectrum antibacterial abilities and releases NO in response to near-infrared (NIR) laser to promote angiogenesis. Notably, MSSH can inhibit excessive proliferation of fibroblasts and effectively reduce scarring caused by deep second-degree burns, as demonstrated by in vitro and in vivo tests.

Cell Migration Assays and Their Application to Wound Healing Assays-A Critical Review

In recent years, cell migration assays (CMAs) have emerged as a tool to study the migration of cells along with their physiological responses under various stimuli, including both mechanical and bio-chemical properties. CMAs are a generic system in that they support various biological applications, such as wound healing assays. In this paper, we review the development of the CMA in the context of its application to wound healing assays. As such, the wound healing assay will be used to derive the requirements on CMAs. This paper will provide a comprehensive and critical review of the development of CMAs along with their application to wound healing assays. One salient feature of our methodology in this paper is the application of the so-called design thinking; namely we define the requirements of CMAs first and then take them as a benchmark for various developments of CMAs in the literature. The state-of-the-art CMAs are compared with this benchmark to derive the knowledge and technological gap with CMAs in the literature. We will also discuss future research directions for the CMA together with its application to wound healing assays.

Highly biocidal poly(vinyl alcohol)-hydantoin/starch hybrid gels: A "Trojan Horse" for Bacillus subtilis

HYPOTHESIS

Poly (vinyl alcohol) (PVA) cryogels can be functionalized with n-Halamines to confer biocidal features useful for their application as wound-dressing tools. Their efficacy can be boosted by stably embedding a polymeric bacterial food source (e.g., starch) in the gel matrix. The bioavailability of the food source lures bacteria inside the gel network via chemotactic mechanisms, promoting their contact with the biocidal functionalities and their consequent inactivation.

EXPERIMENTS

The synthesis of a novel hydantoin-functionalized PVA (H-PVA-hyd) is proposed. The newly synthesized H-PVA-hyd polymer was introduced in the formulation of H-PVA-based cryogels. To promote the cryogelation of the systems we exploited phase-separation mechanisms employing either a PVA carrying residual acetate groups (L-PVA) or starch as phase-segregating components. The permanence of the biocidal functionality after swelling was investigated via proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared (FT-IR) microscopy. The activated H-PVA-hyd cryogels have been tested against bacteria with amylolytic activity (Bacillus subtilis) and the outcomes were analyzed by direct observation via confocal laser scanning microscopy (CLSM).

FINDINGS

The cryogels containing starch resulted in being the most effective (up to 90% bacterial killing), despite carrying a lower amount of hydantoin groups than their starch-free counterparts, suggesting that their improved efficacy relies on a "Trojan Horse" type of mechanism.

Combining Alginate/PVPI-Based Film with Frequency Rhythmic Electrical Modulation System (FREMS) Technology as an Advanced Strategy for Diabetic Wounds

Diabetes is rising as one of the most diffused diseases of the century with the related urgent necessity to face its systemic and local effects on the patients, such as cardiovascular problems, degeneration of limbs, and dysfunction of the wound healing process. The diffusion of leg ulcers has been estimated to be 1.51 for 1000 population, and these non-resolved wounds can produce several social, economic, and mental health issues in diabetic patients. At the same time, these people experience neuropathic pain that causes morbidity and a further decrease in their quality of life. Here, a new study is presented where asodium alginate/Polyvinylpyrrolidone-Iodine complex (PVPI)-based wound dressing is combined with the Frequency Rhythmic Electrical Modulation System (FREMS) technology, an established medical device for the treatment of neuropathic pain and diabetic ulcers. The produced Alginate/PVPI-based films are characterized in terms of morphology, chemistry, wettability, bio-/hemo-compatibility, and clotting capacity. Next, the Alginate/PVPI-based films are used together with FREMS technology in diabetic mice models, and synergism of their action in the wound closure rate and anti-inflammatory properties is found. Hence, how the combination of electrical neurostimulation devices and advanced wound dressings can be a new approach to improve chronic wound treatment is demonstrated.

The effect of κ-carrageenan and ursolic acid on the physicochemical properties of the electrospun nanofibrous mat for biomedical application

Wound dressing materials such as nanofiber (NF) mats have gained a lot of attention in recent years owing to their wonderful effect on accelerating the healing process and protection of wounds. In this regard, three different types of NF mats were fabricated using pure polyvinylpyrrolidone (PVP), PVP/κ-carrageenan (KG), and ursolic acid (UA) in the optimal PVP/KG ratio by electrospinning method to apply them as wound dressings. The morphology, chemical structure, degradation, porosity, mechanical properties and antioxidant activity of the produced NFs were investigated. Moreover, cell studies (e.g., cell proliferation, adhesion, and migration) and their antibacterial properties were evaluated. Adding KG and UA reduced the mean diameter size of the PVP-based NFs to ∼98 nm in the optimal sample, with defect-free morphology. The PVP/KG/UA 0.25 % exhibited the highest porosity, hydrophilicity, and degradation rate and a wound closure rate of 60 %, 2.5 times higher than that of the control group. Furthermore, this sample's proliferation and antibacterial ability were significantly higher than the other groups. These findings confirmed that the produced UA-loaded NFs have excellent properties as wound dressing.

Karaya/Gellan-Gum-Based Bilayer Films Containing 3,3'-Diindolylmethane-Loaded Nanocapsules: A Promising Alternative to Melanoma Topical Treatment

This study aimed to incorporate nanocapsules containing 3,3'-diindolylmethane (DIM) with antitumor activity into a bilayer film of karaya and gellan gums for use in topical melanoma therapy. Nanocarriers and films were prepared by interfacial deposition of the preformed polymer and solvent casting methods, respectively. Incorporating DIM into nanocapsules increased its antitumor potential against human melanoma cells (A-375) (IC50 > 24.00 µg/mL free DIM × 2.89 µg/mL nanocapsules). The films were transparent, hydrophilic (θ < 90°), had homogeneous thickness and weight, and had a DIM content of 106 µg/cm2. Radical ABTS+ scavenger assay showed that the DIM films presented promising antioxidant action. Remarkably, the films showed selective bioadhesive potential on the karaya gum side. Considering the mechanical analyses, the nanotechnology-based films presented appropriate behavior for cutaneous application and controlled DIM release profile, which could increase the residence time on the application site. Furthermore, the nanofilms were found to increase the permeation of DIM into the epidermis, where melanoma develops. Lastly, the films were non-hemolytic (hemolysis test) and non-irritant (HET-CAM assay). In summary, the combination of karaya and gellan gum in bilayer films that contain nanoencapsulated DIM has demonstrated potential in the topical treatment of melanoma and could serve as a viable option for administering DIM for cutaneous melanoma therapy.

Ciprofloxacin-Loaded Polyvinylpyrrolidone Foils for the Topical Treatment of Wound Infections with Methicillin-Resistant Staphylococcus aureus (MRSA)

Bacterial infections are a constant challenge in the management of acute and chronic wounds. Chronic wounds, such as diabetic foot ulcers, have increased significantly in the last few years due to the rise of an aging population. A better understanding of the infectious pathophysiological mechanisms is urgently needed along with new options for the treatment of wound infections and wound-healing disorders. New advances in the preparation of biocompatible dressing materials that can be loaded with antimicrobial drugs may improve the topical treatment of infected wounds. In this study, we investigated the antimicrobial activity of polyvinylpyrrolidone (PVP) foils loaded with ciprofloxacin (Cipro-foils) in the presence of acetic acid as a co-solvent. We used ex vivo human wounds that were infected with two bacterial strains: methicillin-resistant Staphylococcus aureus (MRSA) or Pseudomonas aeruginosa (PAO1). The effectiveness of the treatment was demonstrated by the quantification of the living bacteria extracted from the wound and the detection of released immunological mediators in skin extracts and in the skin culture media. We found that Cipro-foils effectively treated the infection with both PAO1 and MRSA. Other than PAO1, MRSA had no lytic activity toward skin proteins. MRSA infections increased cytokines' expression and release. Interestingly, treatment with Cipro-foils could partially counteract these effects.

Innovative Functional Biomaterials as Therapeutic Wound Dressings for Chronic Diabetic Foot Ulcers

The imbalance of local and systemic factors in individuals with diabetes mellitus (DM) delays, or even interrupts, the highly complex and dynamic process of wound healing, leading to diabetic foot ulceration (DFU) in 15 to 25% of cases. DFU is the leading cause of non-traumatic amputations worldwide, posing a huge threat to the well-being of individuals with DM and the healthcare system. Moreover, despite all the latest efforts, the efficient management of DFUs still remains a clinical challenge, with limited success rates in treating severe infections. Biomaterial-based wound dressings have emerged as a therapeutic strategy with rising potential to handle the tricky macro and micro wound environments of individuals with DM. Indeed, biomaterials have long been related to unique versatility, biocompatibility, biodegradability, hydrophilicity, and wound healing properties, features that make them ideal candidates for therapeutic applications. Furthermore, biomaterials may be used as a local depot of biomolecules with anti-inflammatory, pro-angiogenic, and antimicrobial properties, further promoting adequate wound healing. Accordingly, this review aims to unravel the multiple functional properties of biomaterials as promising wound dressings for chronic wound healing, and to examine how these are currently being evaluated in research and clinical settings as cutting-edge wound dressings for DFU management.

Engineering of clarithromycin loaded stimulus responsive dissolving microneedle patches for the treatment of biofilms

This study aimed to fabricate clarithromycin laden Eudragit S-100-based microfibers (MF), microfibers coated film (MB), clarithromycin loaded polyvinyl pyrollidone, hyaluronic acid and sorbitol-based dissolving microneedle patches (CP) and microfibers coated microneedle patches (MP). Morphological and phase analysis of formulations were carried out by scanning electron microscopy and differential scanning calorimetry, X-ray diffraction, respectively. Substrate liquefaction test, in vitro drug release, antimicrobial assay and in vivo antibiofilm studies were performed. MF exhibited a uniform surface and interconnected network. Morphological analysis of CP revealed sharp-tipped and uniform-surfaced microstructures. Clarithromycin was incorporated within MF and CP as amorphous solid. Liquefaction test indicated hyaluronate lyase enzyme responsiveness of hyaluronic acid. Fibers-based formulations (MF, MB and MP) provided an alkaline pH (7.4) responsive drug release; ∼79 %, ∼78 % and ∼81 %, respectively within 2 hours. CP showed a drug release of ∼82 % within 2 hours. MP showed ∼13 % larger inhibitory zone against Staphylococcus aureus (S. aureus) as compared to MB and CP. A relatively rapid eradication of S. aureus in infected wounds and subsequent skin regeneration was observed following MP application as compared to MB and CP indicating its usefulness for the management of microbial biofilms.

Quercetin-Loaded Polycaprolactone-Polyvinylpyrrolidone Electrospun Membranes for Health Application: Design, Characterization, Modeling and Cytotoxicity Studies

Fibrous membranes of polycaprolactone (PCL)-polyvinylpyrrolidone (PVP) encapsulating 15% wt of quercetin are fabricated by a uniaxial electrospinning technique. Morphological analysis of the electrospun systems proved the fabrication of micrometric fibers (1.58 µm for PCL/PVP and 2.34 µm for quercetin-loaded membrane). The liquid retention degree of the electrospun membranes is evaluated by testing four different liquid media. The contact angle estimation is performed by testing three liquids: phosphate buffer solution, basic solution (pH = 13) and acidic solution (pH = 3), showing high hydrophobicity degree (contact angles > 90°) in all cases. The release of quercetin from the nanofibers in PBS (phosphate buffer solution) and pH = 3 medium, modeled through different models, shows the possibility of a fine tuning of drug release (up to 7 days) for the produced materials. The release profiles attained a plateau regime after roughly 50 h up to 82% and 71% for PBS and pH = 3 media, respectively. Then, since quercetin is known to undergo photooxidation upon UV radiation, release tests after different UV treatment times are carried out and compared with the untreated membrane, demonstrating that the release of the active drug changes from 82% for no-irradiated sample up to 57% after 10 h of UV exposure. The biology activity of released quercetin is evaluated on two human cell lines. The reported results demonstrate the ability of the quercetin-loaded membranes to reduce cell viability of human cell lines in two different conditions: direct contact between cells and quercetin-loaded membranes and cells treatment with culture medium previously conditioned with quercetin-loaded membranes. Therefore, the reported preliminary data confirm the possibility of applying the electrospun quercetin-loaded PCL-PVP membranes for health applications.

Hyaluronic acid association with bacterial, fungal and viral infections: Can hyaluronic acid be used as an antimicrobial polymer for biomedical and pharmaceutical applications?

The relationships between hyaluronic acid (HA) and pathological microorganisms incite new understandings on microbial infection, tissue penetration, disease progression and lastly, potential treatments. These understandings are important for the advancement of next generation antimicrobial therapeutical strategies for the control of healthcare-associated infections. Herein, this review will focus on the interplay between HA, bacteria, fungi, and viruses. This review will also comprehensively detail and discuss the antimicrobial activity displayed by various HA molecular weights for a variety of biomedical and pharmaceutical applications, including microbiology, pharmaceutics, and tissue engineering.

Development of a photosynthetic hydrogel as potential wound dressing for the local delivery of oxygen and bioactive molecules

The development of biomaterials to improve wound healing is a critical clinical challenge and an active field of research. As it is well described that oxygen plays a critical role in almost each step of the wound healing process, in this work, an oxygen producing photosynthetic biomaterial was generated, characterized, and further modified to additionally release other bioactive molecules. Here, alginate hydrogels were loaded with the photosynthetic microalgae Chlamydomonas reinhardtii, showing high integration as well as immediate oxygen release upon illumination. Moreover, the photosynthetic hydrogel showed high biocompatibility in vitro and in vivo, and the capacity to sustain the metabolic oxygen requirements of zebrafish larvae and skin explants. In addition, the photosynthetic dressings were evaluated in 20 healthy human volunteers following the ISO-10993-10-2010 showing no skin irritation, mechanical stability of the dressings, and survival of the photosynthetic microalgae. Finally, hydrogels were also loaded with genetically engineered microalgae to release human VEGF, or pre-loaded with antibiotics, showing sustained release of both bioactive molecules. Overall, this work shows that photosynthetic hydrogels represent a feasible approach for the local delivery of oxygen and other bioactive molecules to promote wound healing. STATEMENT OF SIGNIFICANCE: As oxygen plays a key role in almost every step of the tissue regeneration process, the development of oxygen delivering therapies represents an active field of research, where photosynthetic biomaterials have risen as a promising approach for wound healing. Therefore, in this work a photosynthetic alginate hydrogel-based wound dressing containing C. reinhardtii microalgae was developed and validated in healthy skin of human volunteers. Moreover, hydrogels were modified to additionally release other bioactive molecules such as recombinant VEGF or antibiotics. The present study provides key scientific data to support the use of photosynthetic hydrogels as customizable dressings to promote wound healing.

Recent advancements and perspective of ciprofloxacin-based antimicrobial polymers

In recent years, microbial pathogens, which are major sources of infections, have become a widespread concern across the world. The number of deaths caused by infectious diseases is continually rising, according to World Health Organization records. Antimicrobial resistance, particularly resistance to several drugs, is steadily growing in percentages of organisms. Ciprofloxacin is a second-generation fluoroquinolone with significant antimicrobial activity and pharmacokinetic characteristics. According to studies, many bacteria are resistant to the antibiotic ciprofloxacin. In this article, we look into polymers as ciprofloxacin macromolecular carriers with a wide range of antibacterial activity. We also discuss the latter form of coupling, in which ciprofloxacin and polymers are covalently bonded. This article also discusses the use of antimicrobial polymers in combination with ciprofloxacin in a various sectors. The current review article provides an overview of publications in the last five years on polymer loaded or modified with ciprofloxacin having applications in numerous sectors.

Novel Pullulan/Gellan Gum Bilayer Film as a Vehicle for Silibinin-Loaded Nanocapsules in the Topical Treatment of Atopic Dermatitis

In this study a novel gellan gum/pullulan bilayer film containing silibinin-loaded nanocapsules was developed for topical treatment of atopic dermatitis (AD). The bilayer films were produced by applying a pullulan layer on a gellan gum layer incorporated with silibinin nanocapsules by two-step solvent casting method. The bilayer formation was confirmed by microscopic analysis. In vitro studies showed that pullulan imparts bioadhesitvity for the films and the presence of nanocapsules increased their occlusion factor almost 2-fold. Besides, the nano-based film presented a slow silibinin release and high affinity for cutaneous tissue. Moreover, this film presented high scavenger capacity and non-hemolytic property. In the in vivo study, interestingly, the treatments with vehicle film attenuated the scratching behavior and the ear edema in mice induced by 2,4-dinitrochlorobenzene (DNCB). However, the nano-based film containing silibinin modulated the inflammatory and oxidative parameters in a similar or more pronounced way than silibinin solution and vehicle film, as well as than hydrocortisone, a classical treatment of AD. In conclusion, these data suggest that itself gellan gum/pullulan bilayer film might attenuate the effects induced by DNCB, acting together with silibinin-loaded nanocapsules, which protected the skin from oxidative damage, improving the therapeutic effect in this AD-model.

Recent Progress on Hyaluronan-Based Products for Wound Healing Applications

Hyaluronic acid (HA) based nanocomposites are considered excellent for improving wound healing. HA is biocompatible, biodegradable, non-toxic, biologically active, has hemostatic ability, and resists bacterial adhesion. HA-based nanocomposites promote wound healing in four different sequential phases hemostasis, inflammation, proliferation, and maturation. The unique biological characteristics of HA enable it to serve as a drug, an antibacterial agent, and a growth factor, which combine to accelerate the healing process. In this review, we focus on the use of HA-based nanocomposites for wound healing applications and we describe the importance of HA for the wound healing process in each sequential phase, such as hemostasis, inflammation, proliferation, and maturation. Metal nanoparticles (MNPs) or metal oxide nanoparticles (MO-NPs) loaded with HA nanocomposite are used for wound healing applications. Insights into important antibacterial mechanisms are described in HA nanocomposites. Furthermore, we explain antibiotics loaded with HA nanocomposite and its combination with the MNPs/MO-NPs used for wound healing applications. In addition, HA derivatives are discussed and used in combination with the other polymers of the composite for the wound healing process, as is the role of the polymer in wound healing applications. Finally, HA-based nanocomposites used for clinical trials in animal models are presented for wound healing applications.

Colorimetric Indicators Based on Anthocyanin Polymer Composites: A Review

This review explores the colorimetric indicators based on anthocyanin polymer composites fabricated in the last decade, in order to provide a comprehensive overview of their morphological and compositional characteristics and their efficacy in their various application fields. Notably, the structural properties of the developed materials and the effect on their performance will be thoroughly and critically discussed in order to highlight their important role. Finally, yet importantly, the current challenges and the future perspectives of the use of anthocyanins as components of colorimetric indicator platforms will be highlighted, in order to stimulate the exploration of new anthocyanin sources and the in-depth investigation of all the possibilities that they can offer. This can pave the way for the development of high-end materials and the expansion of their use to new application fields.

Enhanced In Vivo Wound Healing Efficacy of a Novel Hydrogel Loaded with Copper (II) Schiff Base Quinoline Complex (CuSQ) Solid Lipid Nanoparticles

Wound dressings created using nanotechnology are known as suitable substrates to speed up the healing of both acute and chronic wounds. Therapeutic substances can be delivered using these materials. In this study, a hydrogel loaded with Cu (II) Schiff base 8-hydroxy quinoline complex (CuSQ) solid lipid nanoparticles (SLN) was formulated to investigate its wound healing potential in an excision wound healing model in rats. The CuSQ SLN were spherical shaped with sizes ranging from 111 to 202 nm and a polydispersity index (PDI) ranging from 0.43 to 0.76, encapsulation efficiency (EE) % between 85 and 88, and zeta potential (ZP) of −11.8 to −40 mV. The formulated hydrogel showed good homogeneity, good stability, and a pH of 6.4 which indicates no skin irritation and had no cytotoxicity on the human skin fibroblast (HSF) cell line. In the in vivo study, animals were placed in five groups: control, standard, plain hydrogel, low dose, and high dose of CuSQ hydrogel. Both doses of CuSQ showed significantly faster healing rates compared to standard and control rats. In addition, the histopathology study showed more collagen, improved angiogenesis, and intact re-epithelization with less inflammation. A significant increase in transforming growth factor-beta1 (TGF-β1) level and increased immune expression of vascular endothelial growth factor (VEGF) by CuSQ treatment validates its role in collagen synthesis, proliferation of fibroblasts and enhancement of angiogenesis. Matrix metalloproteinase-9 (MMP-9) was found to be significantly reduced after CuSQ treatment. Immunohistochemistry of tumor necrosis factor alpha (TNF-α) revealed a marked decrease in inflammation. Thus, we concluded that CuSQ would be a beneficial drug for cutaneous wound healing since it effectively accelerated wound healing through regulation of various cytokines and growth factors.

Bilayer Hydrogels for Wound Dressing and Tissue Engineering

A large number of different skin diseases such as hits, acute, and chronic wounds dictate the search for alternative and effective treatment options. The wound healing process requires a complex approach, the key step of which is the choice of a dressing with controlled properties. Hydrogel-based scaffolds can serve as a unique class of wound dressings. Presented on the commercial market, hydrogel wound dressings are not found among proposals for specific cases and have a number of disadvantages—toxicity, allergenicity, and mechanical instability. Bilayer dressings are attracting great attention, which can be combined with multifunctional properties, high criteria for an ideal wound dressing (antimicrobial properties, adhesion and hemostasis, anti-inflammatory and antioxidant effects), drug delivery, self-healing, stimulus manifestation, and conductivity, depending on the preparation and purpose. In addition, advances in stem cell biology and biomaterials have enabled the design of hydrogel materials for skin tissue engineering. To improve the heterogeneity of the cell environment, it is possible to use two-layer functional gradient hydrogels. This review summarizes the methods and application advantages of bilayer dressings in wound treatment and skin tissue regeneration. Bilayered hydrogels based on natural as well as synthetic polymers are presented. The results of the in vitro and in vivo experiments and drug release are also discussed.

Self-Adhesive and Antioxidant Poly(vinylpyrrolidone)/Alginate-Based Bilayer Films Loaded with Malva sylvestris Extracts as Potential Skin Dressings

Malva sylvestris (MS) is a medicinal herb known worldwide for its beneficial effects due to the several active molecules present in its leaves and flowers. These compounds have shown antioxidant and anti-inflammatory properties and thus can be helpful in treatments of burns and chronic wounds, characterized mainly by high levels of free radicals and impairments of the inflammatory response. In this work, we propose bilayer films as wound dressings, based on poly(vinylpyrrolidone) (PVP) and sodium alginate loaded with M. sylvestris extracts from leaves and flowers and fabricated by combining solvent-casting and rod-coating methods. The top layer is produced in two different PVP/alginate ratios and loaded with the MS flowers' extract, while the bottom layer is composed of PVP and MS leaves' extract. The bilayers were characterized morphologically, chemically, and mechanically, while they showed superior self-adhesive properties on human skin compared to a commercial skin patch. The materials showed antioxidant activity, release of the bioactive compounds, and water uptake property. Moreover, the anthocyanin content of the flower extract provided the films with the ability to change color when immersed in buffers of different pH levels. In vitro tests using primary keratinocytes demonstrated the biocompatibility of the MS bilayer materials and their capacity to enhance the proliferation of the cells in a wound scratch model. Finally, the best performing MS bilayer sample with a PVP/alginate ratio of 70:30 was evaluated in mice models, showing suitable resorption properties and the capacity to reduce the level of inflammatory mediators in UVB-induced burns when applied to an open wound. These outcomes suggest that the fabricated bilayer films loaded with M. sylvestris extracts are promising formulations as active and multifunctional dressings for treating skin disorders.

Antibacterial biomaterials for skin wound dressing

Bacterial infection and the ever-increasing bacterial resistance have imposed severe threat to human health. And bacterial contamination could significantly menace the wound healing process. Considering the sophisticated wound healing process, novel strategies for skin tissue engineering are focused on the integration of bioactive ingredients, antibacterial agents included, into biomaterials with different morphologies to improve cell behaviors and promote wound healing. However, a comprehensive review on anti-bacterial wound dressing to enhance wound healing has not been reported. In this review, various antibacterial biomaterials as wound dressings will be discussed. Different kinds of antibacterial agents, including antibiotics, nanoparticles (metal and metallic oxides, light-induced antibacterial agents), cationic organic agents, and others, and their recent advances are summarized. Biomaterial selection and fabrication of biomaterials with different structures and forms, including films, hydrogel, electrospun nanofibers, sponge, foam and three-dimension (3D) printed scaffold for skin regeneration, are elaborated discussed. Current challenges and the future perspectives are presented in this multidisciplinary field. We envision that this review will provide a general insight to the elegant design and further refinement of wound dressing.

Evaluation of a Multifunctional Polyvinylpyrrolidone/Hyaluronic Acid-Based Bilayer Film Patch with Anti-Inflammatory Properties as an Enhancer of the Wound Healing Process

The management of acute and chronic wounds is still a socioeconomic burden for society due to the lack of suitable tools capable of supporting all the healing phases. The exponential spread of diabetes worldwide and the consequent increase of complicated diabetic ulcers require further efforts to develop scalable, low-cost, and easy-to-use treatments for tackling this emergency. Recently, we explored the fabrication of a polyvinylpyrrolidone/hyaluronic acid-based bilayer wound dressing, characterizing its physicochemical features and detailing its excellent antimicrobial activity. Here, we further demonstrate its biocompatibility on fibroblasts, keratinocytes, and red blood cells. The bilayer shows anti-inflammatory properties, statistically reducing the level of IL-6, IL-1β, and TNF-α, and a capacity to accelerate wound healing in vitro and in healthy and diabetic mice models compared to untreated mice. The outcomes suggest that this bilayer material can be an effective tool for managing different skin injuries.

Improving Water-Absorption and Mechanical Strength: Lyotropic Liquid Crystalline-Based Spray Dressings as a Candidate Wound Management System

A spray dressing based on lyotropic liquid crystalline (LLC) with adjustable crystalline lattices was investigated in this study. It possesses water-triggering phase transition property and ease of spraying on wound, as well as stable drug encapsulation and controllable drug release. When it comes to wound with exudate, adequate water absorption and sustainable mechanical strength after water absorption was important for a good dressing, while most of the normal LLC dressings were still unable to meet such standards. Herein, a type of hyaluronic acid (HA)-incorporated LLC-based spray dressing (HLCSD) was developed to overcome the above limitations. After comparing HAs with different molecular weights (MWs) and concentrations, 3% HA with MW of 800~1000 kD was chosen as an ideal amount of excipients to add into the HLCSD. The water absorption of HLCSD precursor increased by 150% with the appearance of enlarged water channels. The complex modulus of HLCSD gel also increased from 1 to 100 kPa, which suggested lasting wound coverage and good patient compliance when used clinically. The spraying and phase transition properties of HLCSD was studied and showed acceptable changes. Moreover, good safety comparable with the commercial product Purilon® was also demonstrated in an in vivo acute skin irritation test. Thus, the improved HLCSD was a promising dressing for exudation wound treatment.

Hyaluronic Acid and Graphene Oxide-incorporated Hyaluronic Acid Hydrogels for Electrically Stimulated Release of Anticancer Tamoxifen Citrate

Transdermal drug delivery is the transport of drug across the skin and into the systemic circulation. Patch is a one of transdermal device that is used to attach on skin and contains drug. The drug matrices from hyaluronic acid (HA) and graphene oxide (GO) incorporated HA hydrogel were fabricated for the release of tamoxifen citrate (TMX) as the anticancer drug under applied electrical field. The pristine HA hydrogels as the matrix and GO as the drug encapsulation host were fabricated for transdermal patch by the solution casting using citric acid as the chemical crosslinker. In vitro drug release experiment was investigated by utilizing the modified Franz-diffusion cell under the effects of crosslinking ratio, electric potential, and GO. The TMX release behaviors from the hydrogels were found to be from the three mechanisms: the pure Fickian diffusion; the anomalous or non-Fickian diffusion; and Super case II transport depending on the crosslinking conditions. The TMX diffusion and release amount from the pristine HA hydrogels were increased with smaller crosslinking ratios. With applied electrical potential, the enhanced TMX diffusion and release amount were observed when compared to that without due to the electro-repulsive force. Furthermore, the TMX diffusion from the HA hydrogel with GO as the drug encapsulation host was higher by two orders of magnitude than without GO.

Hydrogel Preparation Methods and Biomaterials for Wound Dressing

Wounds have become one of the causes of death worldwide. The metabolic disorder of the wound microenvironment can lead to a series of serious symptoms, especially chronic wounds that bring great pain to patients, and there is currently no effective and widely used wound dressing. Therefore, it is important to develop new multifunctional wound dressings. Hydrogel is an ideal dressing candidate because of its 3D structure, good permeability, excellent biocompatibility, and ability to provide a moist environment for wound repair, which overcomes the shortcomings of traditional dressings. This article first briefly introduces the skin wound healing process, then the preparation methods of hydrogel dressings and the characteristics of hydrogel wound dressings made of natural biomaterials and synthetic materials are introduced. Finally, the development prospects and challenges of hydrogel wound dressings are discussed.

Antibacterial photodynamic activity of hydrophobic carbon quantum dots and polycaprolactone based nanocomposite processed via both electrospinning and solvent casting method

Inhabitation of various types of bacteria on different surfaces causes vital health problems worldwide. In this work, a wound dressing defeating bacterial infection had been fabricated. The antibacterial effect of polycaprolactone and hydrophobic carbon quantum dots (hCQDs) based nanocomposite has been presented. The nanocomposite was fabricated both via solvent casting and electrospinning method. Nanocomposites with and without hCQDs had been investigated. A detailed study on their morphology and surface properties were performed by scanning electron microscopy, atomic force microscopy and Raman spectroscopy. Prepared nanocomposites had been evaluated by the contact angle, UV-Vis spectroscopy, electron paramagnetic resonance spectroscopy, and antibacterial activity. It was found that nanocomposites were able to produce singlet oxygen upon blue light irradiation at 470 nm, and they were effective in the eradication of Gram positive (Staphylococcus aureus, Listeria monocytogenes) and Gram negative (Escherichia coli, Klebsiella pneumoniae) bacteria.

Hydroxycinnamic Acids and Derivatives Formulations for Skin Damages and Disorders: A Review

Alterations of skin homeostasis are widely diffused in our everyday life both due to accidental injuries, such as wounds and burns, and physiological conditions, such as late-stage diabetes, dermatitis, or psoriasis. These events are locally characterized by an intense inflammatory response, a high generation of harmful free radicals, or an impairment in the immune response regulation, which can profoundly change the skin tissue' repair process, vulnerability, and functionality. Moreover, diabetes diffusion, antibiotic resistance, and abuse of aggressive soaps and disinfectants following the COVID-19 emergency could be causes for the future spreading of skin disorders. In the last years, hydroxycinnamic acids and derivatives have been investigated and applied in several research fields for their anti-oxidant, anti-inflammatory, and anti-bacterial activities. First, in this study, we give an overview of these natural molecules' current source and applications. Afterwards, we review their potential role as valid alternatives to the current therapies, supporting the management and rebalancing of skin disorders and diseases at different levels. Also, we will introduce the recent advances in the design of biomaterials loaded with these phenolic compounds, specifically suitable for skin disorders treatments. Lastly, we will suggest future perspectives for introducing hydroxycinnamic acids and derivatives in treating skin disorders.

Hyaluronic Acid-Based Scaffolds as Potential Bioactive Wound Dressings

The negative factors that result in delayed and prolonged wound healing process include microbial pathogens, excess wound exudates, underlying conditions, smoking, obesity, etc. Most of the currently used wound dressings demonstrate an inadequate capacity to treat wounds resulting from the factors mentioned above. The commonly used wound dressings include hydrogels, films, hydrocolloids, foams, fibers, sponges, dermal patches, bandages, etc. These wound dressings can be loaded with various types of bioactive agents (e.g., antibiotics, nanoparticles, anti-inflammatory drugs, etc.) to improve their therapeutic outcomes. Biopolymers offer interesting properties suitable for the design of wound dressings. This review article will be based on hyaluronic-acid-based scaffolds loaded with therapeutic agents for the treatment of wounds.

Enhanced antimicrobial and full-thickness wound healing efficiency of hydrogels loaded with heparinized ZnO nanoparticles: In vitro and in vivo evaluation

Nanotechnology-based fabricated wound dressings are known as appropriate substrates to enhance healing in both acute and chronic wounds. These types of materials have the ability to deliver therapeutic agents. In this study, a wound dressing including heparinized zinc oxide nanoparticles in combination with chitosan and poly(vinyl alcohol) was developed to investigate its antibacterial and regenerative properties in a rat model of full thickness skin wounds. By adding nanoparticles, the mechanical strength increased up to twice as compared to the sample without nanoparticles. In addition, heparin release profile follows the Hixson-Crowell release kinetic. Protein adsorption enhanced by adding nanoparticles in hydrogels and the prepared wound dressings were completely biocompatible. In terms of antibacterial activity, the minimum inhibitory concentration decreased by conjugation of heparin on the surface of zinc oxide nanoparticles compared to the non-functionalized nanoparticles, and, this shows the increased antibacterial synergistic effect by adding heparin to nanoparticles. Furthermore, it was found that the heparinized zinc oxide nanoparticles effectively accelerate wound closure, re-epithelialization and decrease collagen deposition compared to other groups after implantation. Hence, the prepared wound dressings have the capacity to significantly enhance healing of acute wounds.

Healing of dermal wounds property of Caryocar brasiliense oil loaded polymeric lipid-core nanocapsules: formulation and in vivo evaluation

Cutaneous lesions lead to complications in patients, since they may be recurrent and also represent risk of progression to infection and/or amputation. Therefore, effective, protective, and topical treatments of easy application and removal need to be developed to provide effective alternatives to patients. The Caryocar brasiliense Cambess (CBC) presents important pharmacological activities and proved in the healing process. This paper reports the improvement of the CBC nanostructured (LNC_CBC and LNC_CBC+) activity in dermal wounds in vivo. The oil was physico-chemically characterized and used in the development of lipid-core nanocapsules (LNCs), coated (LNC_CBC+) or without chitosan (LNC_CBC), in concentration of 1.0 mg mL^-1. Hydrogel (HG) was tested in vivo on lesions in the back of male Wistar rats for 14 days. The oil presented appropriate physico-chemical characteristics for its use, such as moisture 0.76 %, acidity 0.85 % and oleic acid 25.90 %. The LNCs showed nanometric size (around 200 nm), monomodal distribution, slight acid pH and zeta potential of + 22.1 mV in accordance with the composition. The nanostructured oil induced dermal healing in vivo showing significantly better improvement than free oil. LNC_CBC+ showed best results showing the higher increase of the production of type 1 collagen, an important protein to the healing repair. These results suggest that development of formulations LNC_CBC and LNC_CBC+ are promising and important alternative for the treatment of dermal wounds, avoiding complications related to cutaneous lesions.

Hyaluronic Acid and Controlled Release: A Review

Hyaluronic acid (HA) also known as hyaluronan, is a natural polysaccharide—an anionic, non-sulfated glycosaminoglycan—commonly found in our bodies. It occurs in the highest concentrations in the eyes and joints. Today HA is used during certain eye surgeries and in the treatment of dry eye disease. It is a remarkable natural lubricant that can be injected into the knee for patients with knee osteoarthritis. HA has also excellent gelling properties due to its capability to bind water very quickly. As such, it is one the most attractive controlled drug release matrices and as such, it is frequently used in various biomedical applications. Due to its reactivity, HA can be cross-linked or conjugated with assorted bio-macromolecules and it can effectively encapsulate several different types of drugs, even at nanoscale. Moreover, the physiological significance of the interactions between HA and its main membrane receptor, CD44 (a cell-surface glycoprotein that modulates cell–cell interactions, cell adhesion and migration), in pathological processes, e.g., cancer, is well recognized and this has resulted in an extensive amount of studies on cancer drug delivery and tumor targeting. HA acts as a therapeutic but also as a tunable matrix for drug release. Thus, this review focuses on controlled or sustained drug release systems assembled from HA and its derivatives. More specifically, recent advances in controlled release of proteins, antiseptics, antibiotics and cancer targeting drugs from HA and its derivatives were reviewed. It was shown that controlled release from HA has many benefits such as optimum drug concentration maintenance, enhanced therapeutic effects, improved efficiency of treatment with less drug, very low or insignificant toxicity and prolonged in vivo release rates.

From fabric to tissue: Recovered wool keratin/polyvinylpyrrolidone biocomposite fibers as artificial scaffold platform

Keratin extracted from wool fibers has recently gained attention as an abundant source of renewable, biocompatible material for tissue engineering and drug delivery applications. However, keratin extraction and processing generally require a copious use of chemicals, not only bearing consequences for the environment but also possibly compromising the envisioned biological outcome. In this study, we present, for the first time, keratin-PVP biocomposite fibers obtained via an all-water co-electrospinning process and explored their properties modulation as a result of different thermal crosslinking treatments. The protein-based fibers featured homogenous morphologies and average diameters in the range of 170-290 nm. The thermomechanical stability and response to a wet environment can be tuned by acting on the curing time; this can be achieved without affecting the 3D fibrous network nor the intrinsic hydrophilic behavior of the material. More interestingly, our protein-based membranes treated at 170 °C for 18 h successfully sustained the attachment and growth of primary human dermal fibroblasts, a cellular model which can recapitulate more faithfully the physiological human tissue conditions. Our proposed approach can be viewed as pivotal in designing tunable protein-based scaffolds for the next generation of skin tissue growth devices.

Antibiotic Delivery Strategies to Treat Skin Infections When Innate Antimicrobial Defense Fails

The epidermal skin barrier protects the body from a host of daily challenges, providing protection against mechanical insults and the absorption of chemicals and xenobiotics. In addition to the physical barrier, the epidermis also presents an innate defense against microbial overgrowth. This is achieved through the presence of a diverse collection of microorganisms on the skin (the "microbiota") that maintain a delicate balance with the host and play a significant role in overall human health. When the skin is wounded, the local tissue with a compromised barrier can become colonized and ultimately infected if bacterial growth overcomes the host response. Wound infections present an immense burden in healthcare costs and decreased quality of life for patients, and treatment becomes increasingly important because of the negative impact that infection has on slowing the rate of wound healing. In this review, we discuss specific challenges of treating wound infections and the advances in drug delivery platforms and formulations that are under development to improve topical delivery of antimicrobial treatments.

Treatment of Coral Wounds by Combining an Antiseptic Bilayer Film and an Injectable Antioxidant Biopolymer

Coral reefs are vital for the marine ecosystem and their potential disappearance can have unequivocal consequences on our environment. Aside from pollution-related threats (changes in water temperature, plastics, and acidity), corals can be injured by diseases, predators, humans and other invasive species. Diseases play an important role in this decline, but so far very few mitigation strategies have been proposed and developed to control this threat. In this work, we demonstrate that recently developed bi-layer human skin wound treatment patches containing antiseptics and natural antioxidants with controlled-release capacity can be adapted to treat scleractinian coral wounds effectively. A hydrophilic bilayer film based on polyvinylpyrrolidone (PVP) and hyaluronic acid was used to cover the open wounds while delivering the antiseptics for rapid action. Afterwards, the hydrophilic bi-layer covered wound was sealed with an antioxidant and hydrophobic ε-caprolactone-p-coumaric acid copolymer by melt injection at low temperatures. Treated coral injuries were monitored both in aquaria system and in natural environment in Maldives for over 4 months to reduce the number of entry points for organisms that could lead to diseases. The corals well-tolerated both biomaterials as well as the antiseptics incorporated in these materials. The treatments displayed self-adhering properties, tuneable dissolution time, and biocompatibility and stimulated regeneration properties within the coral wound. As such, this work demonstrates that certain human skin wound treatment materials can be successfully adapted to the curing of coral wounds and delivery of specific drugs to slow down, reduce or even stop the spread of diseases in scleractinian corals as well as in all other benthic organisms affected by uncontrolled pathologies.

Evaluation of Drug Delivery and Efficacy of Ciprofloxacin-Loaded Povidone Foils and Nanofiber Mats in a Wound-Infection Model Based on Ex Vivo Human Skin

Topical treatment of wound infections is often a challenge due to limited drug availability at the site of infection. Topical drug delivery is an attractive option for reducing systemic side effects, provided that a more selective and sustained local drug delivery is achieved. In this study, a poorly water-soluble antibiotic, ciprofloxacin, was loaded on polyvinylpyrrolidone (PVP)-based foils and nanofiber mats using acetic acid as a solubilizer. Drug delivery kinetics, local toxicity, and antimicrobial activity were tested on an ex vivo wound model based on full-thickness human skin. Wounds of 5 mm in diameter were created on 1.5 × 1.5 cm skin blocks and treated with the investigated materials. While nanofiber mats reached the highest amount of delivered drug after 6 h, foils rapidly achieved a maximum drug concentration and maintained it over 24 h. The treatment had no effect on the overall skin metabolic activity but influenced the wound healing process, as observed using histological analysis. Both delivery systems were efficient in preventing the growth of Pseudomonas aeruginosa biofilms in ex vivo human skin. Interestingly, foils loaded with 500 µg of ciprofloxacin accomplished the complete eradication of biofilm infections with 1 × 109 bacteria/wound. We conclude that antimicrobial-loaded resorbable PVP foils and nanofiber mats are promising delivery systems for the prevention or topical treatment of infected wounds.

Low molecular weight ε-caprolactone-p-coumaric acid copolymers as potential biomaterials for skin regeneration applications

ε-caprolactone-p-coumaric acid copolymers at different mole ratios (ε-caprolactone:p-coumaric acid 1:0, 10:1, 8:1, 6:1, 4:1, and 2:1) were synthesized by melt-polycondensation and using 4-dodecylbenzene sulfonic acid as catalyst. Chemical analysis by NMR and GPC showed that copolyesters were formed with decreasing molecular weight as p-coumaric acid content was increased. Physical characteristics, such as thermal and mechanical properties, as well as water uptake and water permeability, depended on the mole fraction of p-coumaric acid. The p-coumarate repetitive units increased the antioxidant capacity of the copolymers, showing antibacterial activity against the common pathogen Escherichia coli. In addition, all the synthesized copolyesters, except the one with the highest concentration of the phenolic acid, were cytocompatible and hemocompatible, thus becoming potentially useful for skin regeneration applications.

Combining dietary phenolic antioxidants with polyvinylpyrrolidone: transparent biopolymer films based on p-coumaric acid for controlled release

Polyvinylpyrrolidone (PVP) has probably been one of the most utilized pharmaceutical polymers with applications ranging from a blood plasma substitute to nanoparticle drug delivery, since its synthesis in 1939. It is a highly biocompatible, non-toxic and transparent film forming polymer. Although high solubility of PVP in aqueous environment is advantageous, it still poses several problems for some applications in which sustained targeting and release are needed or hydrophobic drug inclusion and delivery systems are to be designed. In this study, we demonstrate that a common dietary phenolic antioxidant, p-coumaric acid (PCA), can be combined with PVP covering a wide range of molar ratios by solution blending in ethanol, forming new transparent biomaterial films with antiseptic and antioxidant properties. PCA not only acts as an effective natural plasticizer but also establishes H-bonds with PVP increasing its resistance to water dissolution. PCA could be released in a sustained manner up to a period of 3 days depending on the PVP/PCA molar ratio. Sustained drug delivery potential of the films was studied using methylene blue and carminic acid as model drugs, indicating that the release can be controlled. Antioxidant and remodeling properties of the films were evaluated in vitro by free radical cation scavenging assay and in vivo on a murine model, respectively. Furthermore, the material resorption of films was slower as PCA concentration increased, as observed from the in vivo full-thickness excision model. Finally, the antibacterial activity of the films against common pathogens such as Escherichia coli and Staphylococcus aureus and the effective reduction of inflammatory agents such as matrix metallopeptidases were demonstrated. All these properties suggest that these new transparent PVP/PCA films can find a plethora of applications in pharmaceutical sciences including skin and wound care.