Synergistic transdermal delivery of nanoethosomes embedded in hyaluronic acid nanogels for enhancing photodynamic therapy

Advances in photodynamic therapy of pathologic scar

Pathologic scars include keloids and hypertrophic scars due to abnormal wound healing. Both cause symptoms of itching and pain; they also affect one's appearance and may even constrain movement. Such scars place a heavy burden on the individual's physical and mental health; moreover, treatment with surgery alone is highly likely to leave more scarring. Therefore, there is an urgent need for a treatment that is both minimally invasive and convenient. Photodynamic therapy (PDT) is an emerging safe and noninvasive technology wherein photosensitizers and specific light sources are used to treat malignant tumors and skin diseases. Research on PDT from both the laboratory and clinic has been reported. These findings on the treatment of pathologic scars using photosensitizers, light sources, and other mechanisms are reviewed in the present article.

Transdermal Transfersome Nanogels Control Hypertrophic Scar Formation via Synergy of Macrophage Phenotype-Switching and Anti-Fibrosis Effect

Hypertrophic scar (HS), which results from prolonged inflammation and excessive fibrosis in re-epithelialized wounds, is one of the most common clinical challenges. Consequently, sophisticated transdermal transfersome nanogels (TA/Fu-TS) are prepared to control HS formation by synergistically inhibiting inflammation and suppressing fibrosis. TA/Fu-TSs have unique structures comprising hydrophobic triamcinolone acetonide (TA) in lipid multilayers and hydrophilic 5-fluorouracil in aqueous cores, and perform satisfactorily with regard to transdermal co-delivery to macrophages and HS fibroblasts in emerging HS tissues. According to the in vitro/vivo results, TA/Fu-TSs not only promote macrophage phenotype-switching to inhibit inflammation by interleukin-related pathways, but also suppress fibrosis to remodel extracellular matrix by collagen-related pathways. Therefore, TA/Fu-TSs overcome prolonged inflammation and excessive fibrosis in emerging HS tissues, and provide an effective therapeutic strategy for controlling HS formation via their synergy of macrophage phenotype-switching and anti-fibrosis effect.

Hyaluronic acid-modified and verteporfin-loaded polylactic acid nanogels promote scarless wound healing by accelerating wound re-epithelialization and controlling scar formation

Wound healing is a common occurrence. However, delayed healing and aberrant scarring result in pathological wound healing. Accordingly, a scarless wound healing remains a significant clinical challenge. In this study, we constructed hyaluronic acid (HA)-modified and verteporfin (VP)-loaded polylactic acid (PLA) nanogels (HA/VP-PLA) to promote scarless wound healing by accelerating wound re-epithelialization and controlling scar formation. Owing to the unique structure of HA incorporating and coating in VP-loaded PLA nanoparticles, HA/VP-PLA could be topically applied on wound to achieve targeted delivery to fibroblasts. Then, HA/VP-PLA released HA and lactic acid (LA) to stimulate the proliferation and migration of fibroblasts, as well as VP to inhibit Yes-associated protein (YAP) expression and nuclear localization to suppress fibrosis. In vitro (skin fibroblasts) and in vivo (rat and rabbit models) experiments strongly suggested that HA/VP-PLA promoted scarless wound healing by accelerating wound re-epithelialization and controlling scar formation. Therefore, our work provides a feasible strategy for scarless wound healing, and the sophisticated HA/VP-PLA exhibit a great potential for clinical applications.

Visible light-driven photodynamic therapy for hypertrophic scars with MOF armored microneedles patch

Photodynamic therapy (PDT) is widely used for the treatment of hypertrophic scars in clinical practice. However, the low transdermal delivery of photosensitizers in scar tissue and protective autophagy induced by Photodynamic therapy greatly reduces the therapeutic efficiency. Therefore, it is necessary to deal with these difficulties for overcoming obstacles in Photodynamic therapy treatment. In this study, a photosensitizer with photocatalytic performance was designed and synthesized using innovative MOFs (metal-organic frameworks). Additionally, the MOFs, together with an autophagy inhibitor chloroquine (CQ), was loaded in a high mechanical strength microneedle patch (MNP) for transdermal delivery. With these functionalized MNP, photosensitizers and chloroquine were delivered deep inside hypertrophic scars. Inhibition of autophagy increases the levels of reactive oxygen species (ROS) under high-intensity visible-light irradiation. Multiprong approaches have been used to remove obstacles in Photodynamic therapy and successfully enhance its anti-scarring effect. In vitro experiments indicated that the combined treatment increased the toxicity of hypertrophic scar fibroblasts (HSFs), downregulated the level of collagen type I expression as well as transforming growth factor-β1 (TGF-β1)expression, decreased the autophagy marker protein LC3II/I ratio, increased the expression of P62. In vivo experiments showed that the MNP had good puncture performance, and significant therapeutic effects were observed in the rabbit ear scar model. These results indicate that functionalized MNP has high potential clinical value.

Silk peptide-hyaluronic acid based nanogels for the enhancement of the topical administration of curcumin

The present study focused on the development of Cur-loaded SOHA nanogels (Cur-SHNGs) to enhance the topical administration of Cur. The physiochemical properties of Cur-SHNGs were characterized. Results showed that the morphology of the Cur-SHNGs was spherical, the average size was 171.37 nm with a zeta potential of −13.23 mV. Skin permeation experiments were carried out using the diffusion cell systems. It was found that the skin retention of Cur-SHNGs was significantly improved since it showed the best retention value (0.66 ± 0.17 μg/cm²). In addition, the hematoxylin and eosin staining showed that the Cur-SHNGs improved transdermal drug delivery by altering the skin microstructure. Fluorescence imaging indicated that Cur-SHNGs could effectively deliver the drug to the deeper layers of the skin. Additionally, Cur-SHNGs showed significant analgesic and anti-inflammatory activity with no skin irritation. Taken together, Cur-SHNGs could be effectively used for the topical delivery of therapeutic drugs.

Polysaccharide-Based Transdermal Drug Delivery

Materials derived from natural plants and animals have great potential for transdermal drug delivery. Polysaccharides are widely derived from marine, herbal, and microbial sources. Compared with synthetic polymers, polysaccharides have the advantages of non-toxicity and biodegradability, ease of modification, biocompatibility, targeting, and antibacterial properties. Currently, polysaccharide-based transdermal drug delivery vehicles, such as hydrogel, film, microneedle (MN), and tissue scaffolds are being developed. The addition of polysaccharides allows these vehicles to exhibit better-swelling properties, mechanical strength, tensile strength, etc. Due to the stratum corneum’s resistance, the transdermal drug delivery system cannot deliver drugs as efficiently as desired. The charge and hydration of polysaccharides allow them to react with the skin and promote drug penetration. In addition, polysaccharide-based nanotechnology enhances drug utilization efficiency. Various diseases are currently treated by polysaccharide-based transdermal drug delivery devices and exhibit promising futures. The most current knowledge on these excellent materials will be thoroughly discussed by reviewing polysaccharide-based transdermal drug delivery strategies.

Microneedle-Mediated Biomimetic Cyclodextrin Metal Organic Frameworks for Active Targeting and Treatment of Hypertrophic Scars

Due to the lack of a delivery system that actively targets hypertrophic scar fibroblasts (HSFs), it is difficult to concentrate the effects of drugs on hypertrophic scars (HSs). We recently discovered that the HSF membrane has a homologous targeting effect and developed an active targeted drug delivery system for the local treatment of HSs. A diphenyl carbonate cross-linked cyclodextrin metal organic framework (CDF) containing more than 26% (w/w) quercetin (QUE) was coated with a HSF membrane (QUE@HSF/CDF) and then dispersed in Bletilla striata polysaccharide (BSP)-fabricated dissolvable microneedles (BSP-MNs-QUE@HSF/CDF) for local administration. This biomimetic nanodrug delivery system improved efficacy on HSs by regulating Wnt/β-catenin and JAK2/STAT3 pathways and reducing the expression of collagens I and III in HS, and this performance was superior to those of systems without HSF functionalization or the assistance of microneedles. Additionally, we found that BSP has synergistic effects and the microneedles have higher mechanical strength and better physical stability than microneedles made of hyaluronic acid. This currently designed drug delivery strategy integrating biomimetic nanoparticles and dissolvable microneedles is promising for applications in the fields of skin disease treatment and cosmetics.

IR-808 loaded nanoethosomes for aggregation-enhanced synergistic transdermal photodynamic/photothermal treatment of hypertrophic scars

Synergistic transdermal photodynamic therapy (PDT)/photothermal therapy (PTT) has emerged as a novel strategy for improving hypertrophic scar (HS) therapeutic outcomes. Herein, a near-infrared heptamethine cyanine dye, named IR-808, has been selected as the desirable photosensitizer owing to its PDT and PTT properties. Benefitting from the transdermal delivery ability of ethosomes (ESs), IR-808 loaded nanoethosomes (IR-808-ES) have been prepared as a novel nanophotosensitizer for the transdermal PDT/PTT of HSs. The special structure of IR-808 aggregate distribution in the ES lipid membrane enhances ROS generation and hyperthermia. The in vitro experiments indicate that the IR-808-ES enhances the PDT/PTT efficacy for inducing the HS fibroblast (HSF) apoptosis via the intrinsic mitochondrial pathway. Furthermore, the in vivo transdermal delivery studies reveal that the IR-808-ES efficiently delivers IR-808 into HSFs in the HS tissue. Systematic assessments in the rabbit ear HS models demonstrate that the enhanced PDT/PTT performance of the IR-808-ES has remarkable therapeutic effects on improving the HS appearance, promoting HSF apoptosis and remodeling collagen fibers. Therefore, the IR-808-ES integrates both the transdermal delivery ability and the aggregation-enhanced PDT/PTT effect, and these features endow the IR-808-ES with significant potential as a novel nanophotosensitizer for the transdermal phototherapy of HSs in the clinical field.

Targeting delivery and minimizing epidermal diffusion of tranexamic acid by hyaluronic acid-coated liposome nanogels for topical hyperpigmentation treatment

Hyperpigmentation is a common complaint and distressing problem in dermatology, and tranexamic acid (TA) is an effective treatment agent but limited by the delivery to melanocytes in the epidermis. Herein, a novel TA naogels (named HA/TA-LP), combining the advantages of liposomes and hyaluronic acid (HA), are prepared and assessed for topical hyperpigmentation treatment with targeting delivery and minimizing epidermal diffusion. Morphological characteristics indicate numerous TA-loaded liposomes packed in HA gels. In vitro cell studies using human A375 melanoma cells show that HA/TA-LP can promote the uptake of TA by targeting delivery with resulting inhibition of tyrosinase activity and melanin production. Guinea pigs are used to construct hyperpigmentation models and investigate the topical delivery and treatment efficacy of HA/TA-LP. In vivo topical delivery studies indicate HA/TA-LP realize the effective delivery into melanocytes with an ideal balance of effective permeability and minimizing epidermal diffusion. Subsequently, hyperpigmentation treatment assessments reveal that HA/TA-LP inhibit tyrosinase activity and melanin production under the radiation of UVB. Our study identifies favorable properties of HA/TA-LP for treating hyperpigmentation, and provides an experimental basis for further clinical application.

Photosensitizer-Functionalized Nanocomposites for Light-Activated Cancer Theranostics

Photosensitizers (PSs) have received significant attention recently in cancer treatment due to its theranostic capability for imaging and phototherapy. These PSs are highly responsive to light source of a suitable wavelength for image-guided cancer therapy from generated singlet oxygen and/or thermal heat. Various organic dye PSs show tremendous attenuation of tumor cells during cancer treatment. Among them, porphyrin and chlorophyll-based ultraviolet-visible (UV-Vis) dyes are employed for photodynamic therapy (PDT) by reactive oxygen species (ROS) and free radicals generated with 400-700 nm laser lights, which have poor tissue penetration depth. To enhance the efficacy of PDT, other light sources such as red light laser and X-ray have been suggested; nonetheless, it is still a challenging task to improve the light penetration depth for deep tumor treatment. To overcome this deficiency, near infrared (NIR) (700-900 nm) PSs, indocyanine green (ICG), and its derivatives like IR780, IR806 and IR820, have been introduced for imaging and phototherapy. These NIR PSs have been used in various cancer treatment modality by combining photothermal therapy (PTT) and/or PDT with chemotherapy or immunotherapy. In this review, we will focus on the use of different PSs showing photothermal/photodynamic response to UV-Vis or NIR-Vis light. The emphasis is a comprehensive review of recent smart design of PS-loaded nanocomposites for targeted delivery of PSs in light-activated combination cancer therapy.

Functional Transdermal Nanoethosomes Enhance Photodynamic Therapy of Hypertrophic Scars via Self-Generating Oxygen

Photodynamic therapy (PDT) is a new therapeutic strategy for hypertrophic scars (HSs), and nanoethosomes (ES) have attracted considerable attention as an efficient transdermal delivery system for PDT of HSs (HS-PDT). However, the delivery of photosensitizers and the hypoxic microenvironment of HSs limit HS-PDT efficacy. Consequently, functional transdermal ES (A/A-ES) that are loaded with the photosensitizer, 5-aminolevulinic acid (ALA), and immobilized nanoenzyme Au nanoclusters (ANCs) within the ES surface have been developed that exhibit superior co-delivery characteristics and produce catalase that enhances HS-PDT efficacy. The unique structure of A/A-ES enables them to co-deliver ALA and ANCs into the HS tissue and to efficiently decompose the endogenous hydrogen peroxide in the HS to generate oxygen. The findings from in vitro and in vivo experiments demonstrated that A/A-ES efficiently co-delivered ALA and ANCs into the HS tissue and that they improved the hypoxic microenvironment of the HS. Systematic assessments reveal that A/A-ES enhance HS-PDT efficacy and that they are highly effective at improving the morphology and promoting HS fibroblast apoptosis and the rearrangement of collagen. These works give rise to an effective treatment option for HSs that integrates the transdermal co-delivery of ALA and nanoenzymes, thereby enabling them to exert their respective beneficial effects, and they highlight the enhancement of HS-PDT efficacy via self-generating oxygen.

Rational Design of Smart Hydrogels for Biomedical Applications

Hydrogels are polymeric three-dimensional network structures with high water content. Due to their superior biocompatibility and low toxicity, hydrogels play a significant role in the biomedical fields. Hydrogels are categorized by the composition from natural polymers to synthetic polymers. To meet the complicated situation in the biomedical applications, suitable host–guest supramolecular interactions are rationally selected. This review will have an introduction of hydrogel classification based on the formulation molecules, and then a discussion over the rational design of the intelligent hydrogel to the environmental stimuli such as temperature, irradiation, pH, and targeted biomolecules. Further, the applications of rationally designed smart hydrogels in the biomedical field will be presented, such as tissue repair, drug delivery, and cancer therapy. Finally, the perspectives and the challenges of smart hydrogels will be outlined.