Bioresponsive Nanoarchitectonics-Integrated Microneedles for Amplified Chemo-Photodynamic Therapy against Acne Vulgaris

Nanocarrier-Integrated Microneedles: Divulging the Potential of Novel Frontiers for Fostering the Management of Skin Ailments

The various kinds of nanocarriers (NCs) have been explored for the delivery of therapeutics designed for the management of skin manifestations. The NCs are considered as one of the promising approaches for the skin delivery of therapeutics attributable to sustained release and enhanced skin penetration. Despite the extensive applications of the NCs, the challenges in their delivery via skin barrier (majorly stratum corneum) have persisted. To overcome all the challenges associated with the delivery of NCs, the microneedle (MN) technology has emerged as a beacon of hope. Programmable drug release, being painless, and its minimally invasive nature make it an intriguing strategy to circumvent the multiple challenges associated with the various drug delivery systems. The integration of positive traits of NCs and MNs boosts therapeutic effectiveness by evading stratum corneum, facilitating the delivery of NCs through the skin and enhancing their targeted delivery. This review discusses the barrier function of skin, the importance of MNs, the types of MNs, and the superiority of NC-loaded MNs. We highlighted the applications of NC-integrated MNs for the management of various skin ailments, combinational drug delivery, active targeting, in vivo imaging, and as theranostics. The clinical trials, patent portfolio, and marketed products of drug/NC-integrated MNs are covered. Finally, regulatory hurdles toward benchtop-to-bedside translation, along with promising prospects needed to scale up NC-integrated MN technology, have been deliberated. The current review is anticipated to deliver thoughtful visions to researchers, clinicians, and formulation scientists for the successful development of the MN-technology-based product by carefully optimizing all the formulation variables.

Epsilon-poly-l-lysine microneedle patch loaded with amorphous doxycycline nanoparticles for synergistic treatment of skin infection

The development of antibiotic-loaded microneedles has been hindered for years by limited excipient options, restricted drug-loading space, poor microneedle formability, and short-term drug retention. Therefore, this study proposes a dissolving microneedle fabricated from the host-defense peptide ε-poly-l-lysine (EPL) as an antibacterial adjuvant system for delivering antibiotics. EPL serves not only as a major matrix material for the microneedle tips, but also as a broad-spectrum antibacterial agent that facilitates the intracellular accumulation of the antibiotic doxycycline (DOX) by increasing bacterial cell membrane permeability. Furthermore, the formation of physically crosslinked networks of EPL affords microneedle tips with improved formability, good mechanical properties, and amorphous nanoparticles (approximately 7.2 nm) of encapsulated DOX. As a result, a high total loading content of both antimicrobials up to 2319.1 μg/patch is achieved for efficient transdermal drug delivery. In a Pseudomonas aeruginosa-induced deep cutaneous infection model, the EPL microneedles demonstrates potent and long-term effects by synergistically enhancing antibiotic activities and prolonging drug retention in infected lesions, resulting in remarkable therapeutic efficacy with 99.91 % (3.04 log) reduction in skin bacterial burden after a single administration. Overall, our study highlights the distinct advantages of EPL microneedles and their potential in clinical antibacterial practice when loaded with amorphous DOX nanoparticles.

Dissolving Hyaluronic Acid-Based Microneedles to Transdermally Deliver Eugenol Combined with Photothermal Therapy for Acne Vulgaris Treatment

A microneedle transdermal drug delivery system simultaneously avoids systemic toxicity of oral administration and low efficiency of traditional transdermal administration, which is of great significance for acne vulgaris therapy. Herein, eugenol-loaded hyaluronic acid-based dissolving microneedles (E@P-EO-HA MNs) with antibacterial and anti-inflammatory activities are developed for acne vulgaris therapy via eugenol transdermal delivery integrated with photothermal therapy. E@P-EO-HA MNs are pyramid-shaped with a sharp tip and a hollow cavity structure, which possess sufficient mechanical strength to penetrate the stratum corneum of the skin and achieve transdermal delivery, in addition to excellent in vivo biocompatibility. Significantly, E@P-EO-HA MNs show effective photothermal therapy to destroy sebaceous glands and achieve antibacterial activity against deep-seated Propionibacterium acnes (P. acnes) under near-infrared-light irradiation. Moreover, cavity-loaded eugenol is released from rapidly dissolved microneedle bodies to play a sustained antibacterial and anti-inflammatory therapy on the P. acnes infectious wound. E@P-EO-HA MNs based on a synergistic therapeutic strategy combining photothermal therapy and eugenol transdermal administration can significantly alleviate inflammatory response and ultimately facilitate the repair of acne vulgaris. Overall, E@P-EO-HA MNs are expected to be clinically applied as a functional minimally invasive transdermal delivery strategy for superficial skin diseases therapy in skin tissue engineering.

Enhancing Tranexamic Acid Penetration through AQP-3 Protein Triggering via ZIF-8 Encapsulation for Melasma and Rosacea Therapy

The systemic use of tranexamic acid (TA) as an oral drug can bring adverse reactions, while intradermal injection leads to pain and a risk of infection. Moreover, it is difficult for highly hydrophilic TA to penetrate the skin barrier that contains lots of hydrophobic lipid compounds, which poses enormous restrictions on its topical application. Current transdermal TA delivery strategies are suffering from low drug load rates, plus their synthesis complexity, time-consumption, etc. adding to the difficulty of TA topical application in clinical therapeutics. To increase the penetration of TA, a novel approach using TA-loaded ZIF-8 (TA@ZIF-8) is developed. The encapsulation efficiency of TA@ZIF-8 reaches ≈25% through physical adsorption and chemical bonding of TA indicates by theoretical simulation and the improved TA penetration is elevated through activating the aquaporin-3 (AQP-3) protein. Additionally, in vivo and in vitro experiments demonstrate the preponderance of TA@ZIF-8 for penetration ability and the advantages in intracellular uptake, minor cytotoxicity, and inhibition of melanogenesis and inflammatory factors. Moreover, clinical trials demonstrate the safety and efficacy of TA@ZIF-8 in the treatment of melasma and rosacea. This work presents a potential topical application of TA, free from the safety concerns associated with systemic drug administration.

Smart Physical-Based Transdermal Drug Delivery System:Towards Intelligence and Controlled Release

Transdermal drug delivery systems based on physical principles have provided a stable, efficient, and safe strategy for disease therapy. However, the intelligent device with real-time control and precise drug release is required to enhance treatment efficacy and improve patient compliance. This review summarizes the recent developments, application scenarios, and drug release characteristics of smart transdermal drug delivery systems fabricated with physical principle. Special attention is paid to the progress of intelligent design and concepts in of physical-based transdermal drug delivery technologies for real-time monitoring and precise drug release. In addition, facing with the needs of clinical treatment and personalized medicine, the recent progress and trend of physical enhancement are further highlighted for transdermal drug delivery systems in combination with pharmaceutical dosage forms to achieve better transdermal effects and facilitate the development of smart medical devices. Finally, the next generation and future application scenarios of smart physical-based transdermal drug delivery systems are discussed, a particular focus in vaccine delivery and tumor treatment.

Nanoparticle-integrated dissolving microneedles for the co-delivery of R848/aPD-1 to synergistically reverse the immunosuppressive microenvironment of triple-negative breast cancer

Nowadays, effective immunotherapy against triple-negative breast cancer (TNBC) remains challenging due to the immunosuppressive tumor microenvironment. Immune checkpoint inhibitor is mostly employed to restore the activity of tumor-specific immune cells, which however brings little therapeutic outcome owing to the limited number of tumor-infiltrating CD8+ T cells and the inefficient delivery of immune drugs to the tumor tissue. Aiming to solve these problems, we herein constructed a tailor-made dissolving microneedle co-encapsulating the TLR7/8 agonist R848 and the immune checkpoint inhibitor aPD-1, termed αNP-RNP@DMN, and fabricated it as a transdermal drug delivery system. This well-designed microneedle patch, endowed with efficient tumor drug delivery ability, was able to mature tumor-infiltrating dendritic cells (TIDCs) and further promote the infiltration of CD8+ T cells into the tumor tissue with the aid of R848. Moreover, the introduction of aPD-1 blocked the programmed cell death protein 1/programmed cell death ligand 1(PD-1/PD-L1) immune checkpoints, synergistically reversing the immunosuppressive microenvironment of TNBC. In vivo therapeutic results demonstrated that αNP-RNP@DMN not only significantly prolonged the survival time of 4T1 tumor-bearing mice, but also inhibited tumor recurrence and lung metastasis after surgery, implying the great potential of this effective drug delivery system for enhanced immunotherapy of superficial tumors. STATEMENT OF SIGNIFICANCE: The limited number of tumor-infiltrating CD8+ T cells and the inefficient delivery of immune drugs to the tumor tissue hinder the effective immunotherapy of triple-negative breast cancer (TNBC). Herein, a dissolving microneedle co-encapsulating TLR7/8 agonist R848 and immune checkpoint inhibitor aPD-1 was developed and fabricated as a transdermal drug delivery system. This tailor-made microneedle patch not only promoted drug accumulation in tumor sites in a safe and painless manner, but also lifted the immune-suppressive state of tumor-infiltrating dendritic cells (TIDCs). The activated TIDCs further enhanced T-cell infiltration into the tumor tissue, thus successfully boosting the therapeutic efficacy of aPD-1. This study demonstrated that this well-designed microneedle patch could be served as an effective drug delivery system for enhanced immunotherapy of TNBC.

Solution blow spun bilayer chitosan/polylactic acid nanofibrous patch with antibacterial and anti-inflammatory properties for accelerating acne healing

The quercetin (QC) loaded chitosan (CS) nanofibrous patch (CSQC) was designed and fabricated successfully by solution blow spinning (SBS). And it was employed to explore a functional double-layer nanofibrous patch (CSQC/PLA) with polylactic acid (PLA) for overcoming the resistance of acne-causing bacteria to antibiotics and local cutaneous irritation. The nanofibrous patch possessed a fluffy bilayer structure with good air permeability, which may be befitted from the SBS method. The 10 % QC loaded CSQC0.10/PLA had sustained release ability of QC for 24 h. A high free radical clearance rate (91.18 ± 2.26 %) and robust antibacterial activity against P. acnes (94.4 %) were achieved for CSQC0.10/PLA with excellent biocompatibility. Meanwhile, E. coli and S. aureus were also suppressed with 99.4 % and 99.2 %, respectively. Moreover, the expression of pro-inflammatory cytokines (IL-6 and TNF-α) was significantly reduced, conducive to acne healing. Therefore, the CSQC0.10/PLA bilayer nanofibrous patch designed here may shed some light on developing multifunctional materials for treating acne infectious wounds.

In-situ-sprayed therapeutic hydrogel for oxygen-actuated Janus regulation of postsurgical tumor recurrence/metastasis and wound healing

Surgery is the mainstay of treatment modality for malignant melanoma. However, the deteriorative hypoxic microenvironment after surgery is recognized as a stemming cause for tumor recurrence/metastasis and delayed wound healing. Here we design and construct a sprayable therapeutic hydrogel (HIL@Z/P/H) encapsulating tumor-targeted nanodrug and photosynthetic cyanobacteria (PCC 7942) to prevent tumor recurrence/metastasis while promote wound healing. In a postsurgical B16F10 melanoma model in female mice, the nanodrug can disrupt cellular redox homeostasis via the photodynamic therapy-induced cascade reactions within tumor cells. Besides, the photosynthetically generated O2 by PCC 7942 can not only potentiate the oxidative stress-triggered cell death to prevent local recurrence of residual tumor cells, but also block the signaling pathway of hypoxia-inducible factor 1α to inhibit their distant metastasis. Furthermore, the long-lasting O2 supply and PCC 7942-secreted extracellular vesicles can jointly promote angiogenesis and accelerate the wound healing process. Taken together, the developed HIL@Z/P/H capable of preventing tumor recurrence/metastasis while promoting wound healing shows great application potential for postsurgical cancer therapy.

Porphyrin and doxorubicin mediated nanoarchitectonics of copper clusters: a bimodal theranostics for cancer diagnosis and treatment in vitro

Nanoarchitectonics, an emerging strategy, presents a promising alternative for developing highly efficient next-generation functional materials. Multifunctional materials developed using nanoarchitectonics help to mimic biological molecules. Porphyrin-based molecules can be effectively utilized to design such assemblies. Metal nanocluster is one of the functional materials that can shed more insight into developing nanoarchitectonic materials. Herein, an inherently near-infrared (NIR) fluorescing copper nanocluster (CuC)-mediated structural assembly via protoporphyrin IX (PPIX) and doxorubicin (Dox) is demonstrated as the functional material. Dox-loaded porphyrin-mediated CuC assembly shows singlet oxygen generation and 66% drug release at 15 min. Furthermore, the efficacy of this material is tested for cancer diagnosis and bimodal therapeutic strategy due to the fluorescing ability of the cluster and loading of PPIX as well as the drug, respectively. The nanoarchitecture exhibits targeted imaging and 83% cell death in HeLa cells upon laser irradiation with 10 nmoles and 20 nmoles of PPIX and Dox, respectively.

Metal-Organic Frameworks and Their Composites for Chronic Wound Healing: From Bench to Bedside

Chronic wounds are characterized by delayed and dysregulated healing processes. As such, they have emerged as an increasingly significant threat. The associated morbidity and socioeconomic toll are clinically and financially challenging, necessitating novel approaches in the management of chronic wounds. Metal-organic frameworks (MOFs) are an innovative type of porous coordination polymers, with low toxicity and high eco-friendliness. Documented anti-bacterial effects and pro-angiogenic activity predestine these nanomaterials as promising systems for the treatment of chronic wounds. In this context, the therapeutic applicability and efficacy of MOFs remain to be elucidated. It is, therefore, reviewed the structural-functional properties of MOFs and their composite materials and discusses how their multifunctionality and customizability can be leveraged as a clinical therapy for chronic wounds.

Advances of Smart Stimulus-Responsive Microneedles in Cancer Treatment

Microneedles (MNs) have emerged as a highly promising technology for delivering drugs via the skin. They provide several benefits, including high drug bioavailability, non-invasiveness, painlessness, and high safety. Traditional strategies for intravenous delivery of anti-tumor drugs have risks of systemic toxicity and easy development of drug resistance, while MN technology facilitates precise delivery and on-demand release of drugs in local tissues. In addition, by further combining with stimulus-responsive materials, the construction of smart stimulus-responsive MNs can be achieved, which can respond to specific physical/chemical stimuli from the internal or external environment, thereby further improving the accuracy of tumor treatment and reducing toxicity to surrounding tissues/cells. This review systematically summarizes the classification, materials, and reaction mechanisms of stimulus-responsive MNs, outlines the benefits and challenges of various types of MNs, and details their application and latest progress in cancer treatment. Finally, the development prospects of smart MNs in tumor treatment are also discussed, bringing inspiration for future precision treatment of tumors.

An Integrated Therapeutic and Preventive Nanozyme-Based Microneedle for Biofilm-Infected Diabetic Wound Healing

The healing of biofilm-infected diabetic wounds characterized by a deteriorative tissue microenvironment represents a substantial clinical challenge. Current treatments remain unsatisfactory due to the limited antibiofilm efficacy caused by weak tissue and biofilm permeability of drugs and the risk of reinfection during the healing process. To address these issues, an integrated therapeutic and preventive nanozyme-based microneedle (denoted as Fe2 C/GOx@MNs) is engineered. The dissolvable tips with enough mechanical strength can deliver and rapidly release Fe2 C nanoparticles (NPs)/glucose oxidase (GOx) in the biofilm active regions, enhancing tissue and biofilm permeability of Fe2 C NPs/GOx, ultimately achieving highly efficient biofilm elimination. Meanwhile, the chitosan backing layer can not only act as an excellent physical barrier between the wound bed and the external environment, but also prevent the bacterial reinvasion during wound healing with its superior antibacterial property. Significantly, the biofilm elimination and reinfection prevention abilities of Fe2 C/GOx@MNs on wound healing are proved on methicillin-resistant Staphylococcus aureus-biofilm-infected diabetic mouse model with full-thickness wound. Together, these results demonstrate the promising clinical application of Fe2 C/GOx@MNs in biofilm-infected wound healing.

Flexible Monitoring, Diagnosis, and Therapy by Microneedles with Versatile Materials and Devices toward Multifunction Scope

Microneedles (MNs) have drawn rising attention owing to their merits of convenience, noninvasiveness, flexible applicability, painless microchannels with boosted metabolism, and precisely tailored multifunction control. MNs can be modified to serve as novel transdermal drug delivery, which conventionally confront with the penetration barrier caused by skin stratum corneum. The micrometer-sized needles create channels through stratum corneum, enabling efficient drug delivery to the dermis for gratifying efficacy. Then, incorporating photosensitizer or photothermal agents into MNs can conduct photodynamic or photothermal therapy, respectively. Besides, health monitoring and medical detection by MN sensors can extract information from skin interstitial fluid and other biochemical/electronic signals. Here, this review discloses a novel monitoring, diagnostic, and therapeutic pattern by MNs, with elaborate discussion about the classified formation of MNs together with various applications and inherent mechanism. Hereby, multifunction development and outlook from biomedical/nanotechnology/photoelectric/devices/informatics to multidisciplinary applications are provided. Programmable intelligent MNs enable logic encoding of diverse monitoring and treatment pathways to extract signals, optimize the therapy efficacy, real-time monitoring, remote control, and drug screening, and take instant treatment.

Novel Double-Layer Dissolving Microneedles for Transmucosal Sequential Delivery of Multiple Drugs in the Treatment of Oral Mucosa Diseases

The development of transmucosal drug delivery systems is a practical requirement in oral clinical practice, and controlled sequential delivery of multiple drugs is usually required. On the basis of the previous successful construction of monolayer microneedles (MNs) for transmucosal drug delivery, we designed transmucosal double-layer sequential dissolving MNs using hyaluronic acid methacryloyl (HAMA), hyaluronic acid (HA), and polyvinyl pyrrolidone (PVP). MNs have the advantages of small size, easy operation, good strength, rapid dissolution, and one-time delivery of two drugs. Morphological test results showed that the HAMA-HA-PVP MNs were small and intact in structure. The mechanical strength and mucosal insertion test results indicated the HAMA-HA-PVP MNs had appropriate strength and could penetrate the mucosal cuticle quickly to achieve transmucosal drug delivery. The in vitro and in vivo experiment results of the double-layer fluorescent dyes simulating drug release revealed that MNs had good solubility and achieved stratified release of the model drugs. The results of the in vivo and in vitro biosafety tests also indicated that the HAMA-HA-PVP MNs were biosafe materials. The therapeutic effect of drug-loaded HAMA-HA-PVP MNs in the rat oral mucosal ulcer model demonstrated that these novel HAMA-HA-PVP MNs quickly penetrated the mucosa, dissolved and effectively released the drug, and achieved sequential drug delivery. Compared to monolayer MNs, these HAMA-HA-PVP MNs can be used as double-layer drug reservoirs for controlled release, effectively releasing the drug in the MN stratification by dissolution in the presence of moisture. The need for secondary or multiple injections can be avoided, thus improving patient compliance. This drug delivery system can serve as an efficient, multipermeable, mucosal, and needle-free alternative for biomedical applications.

ZIF-8 integrated with polydopamine coating as a novel nano-platform for skin-specific drug delivery

Metal-organic frameworks (MOFs) are highly promising as a novel class of drug delivery carriers; however, there are few reports about their application in nanoparticle-based formulations for dermal administration. In this work, we developed a novel kind of nanoparticular system based on zeolitic imidazolate framework-8 (ZIF-8) and polydopamine (PDA) modification for improving the dermal delivery of 5-fluorouracil (5-FU). The structures and properties of the prepared nanoparticles were characterized using a variety of analytical methods. Their ex vivo delivery performance in the skin was investigated using Franz cells, and the underlying mechanisms were studied via confocal laser scanning microscopy (CLSM) and hematoxylin-eosin (HE) experiments which were employed to probe the penetration pathway and the interaction between nanoparticles and the skin. The results revealed that both 5-FU@ZIF-8 and ZIF-8@5-FU@PDA had an enhancement effect on the deposition of 5-FU in the skin, and the surface coating of PDA could further reduce drug permeation across the skin, especially in the case of impaired skin, in comparison with the drug solution. The CLSM study using rhodamine 6G as the fluorescent probe to mimic 5-FU indicated that ZIF-8 and ZIF-8@PDA could deliver their payloads into the skin via two pathways, i.e., intercellular and follicular ones, and the follicular route was shown to be particularly important for ZIF-8@PDA, in which the drug and carrier were co-delivered into the skin as an intact particle. This study provides evidence for using ZIF-8 and PDA modification for skin-specific drug delivery and offers an effective avenue to develop novel nanoplatforms for dermal application to treat skin diseases.

Debridement of contaminated implants using air-polishing coupled with pH-responsive maximin H5-embedded metal-organic frameworks

The primary goal of peri-implantitis treatments remains the decontamination of implant surfaces exposed to polymicrobial biofilms and renders biocompatibility. In this study, we reported a synergistic strategy for the debridement and re-osteogenesis of contaminated titanium by using erythritol air abrasion (AA) coupled with an as-synthesized pH-responsive antimicrobial agent. Here, the anionic antibacterial peptide Maximin H5 C-terminally deaminated isoform (MH5C) was introduced into the Zeolitic Imidazolate Frameworks (ZIF-8) via a one-pot synthesis process. The formed MH5C@ZIF-8 nanoparticles (NPs) not only possessed suitable stability, but also guarantee the slow-release effect of MH5C. Antibacterial experiments revealed that MH5C@ZIF-8 NPs exhibited excellent antimicrobial abilities toward pathogenic bacteria of peri-implantitis, confirming ZIF-8 NPs as efficient nanoplatforms for delivering antibacterial peptide. To evaluate the comprehensive debridement efficiency, single-species as well as mixed-species biofilms were successively established on commercially used titanium surfaces and decontaminated with different methods: removed only by erythritol air abrasion, treated merely with MH5C@ZIF-8 NPs, or received both managements. The results demonstrated that only erythritol air abrasion accompanied with MH5C@ZIF-8 NPs at high concentrations eliminated almost all retained bacteria and impeded biofilm rehabilitation, while neither erythritol air abrasion nor MH5C@ZIF-8 NPs alone could achieve this. Subsequently, we evaluated the re-osteogenesis on previously contaminated surfaces which were treated with different debridement methods afterwards. We found that cell growth and osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) in the group received both treatments (AA + MH5C@ZIF-8) were higher than those in other groups. Our work emphasized the great potential of the synergistic therapy as a credible alternative for removing microorganisms and rendering re-osseointegration on contaminated implant surfaces, boding well for the comprehensive applications in peri-implantitis treatments.

Composite Separable Microneedles for Transdermal Delivery and Controlled Release of Salmon Calcitonin for Osteoporosis Therapy

A composite separable microneedles (MNs) system consisting of silk fibroin (SF) needle tips and hyaluronic acid (HA) base is developed for transdermal delivery of salmon calcitonin (sCT) for therapy of osteoporosis. Poly(ethylene glycol) (PEG) is used to modulate the conformation structure of SF to achieve controllable sustained release of sCT. The prepared MNs can effectively penetrate the skin stratum corneum. After application to the skin, the HA base is dissolved within 2 min, allowing these SF drug depots to be implanted into the skin for controllable sustained release of sCT. The release kinetics of sCT can be controlled by regulating the conformation of SF with PEG and the interaction between sCT peptide and SF proteins. Compared with traditional needle injection, delivery of sCT using optimized HA-PEG/SF MNs shows better trabecular bone repair for ovariectomized-induced osteoporosis in mice. The proposed MNs system provides a new noninjection strategy for therapy of osteoporosis.

Demonstrating Biological Fate of Nanoparticle-Loaded Dissolving Microneedles with Aggregation-Caused Quenching Probes: Influence of Application Sites

Integrating dissolving microneedles (DMNs) and nanocarriers (NC) holds great potential in transdermal drug delivery because it can simultaneously overcome the stratum corneum barrier and achieve efficient and controlled drug delivery. However, different skin sites with different thicknesses and compositions can affect the transdermal diffusion of NC-loaded DMNs. There are few reports on the biological fate (especially transdermal diffusion) of NC-loaded DMNs, and inaccurate bioimaging information of intact NC limits the accurate understanding of the in vivo fate of NC-loaded DMNs. The aggregation-caused quenching (ACQ) probes P4 emitted intense fluorescence signals in intact NC while quenched after the degradation of NC, had been demonstrated the feasibility of label intact NC. In this study, P4 was loaded in solid lipid nanoparticles (SLNs), and further encapsulated into DMNs, to track the transdermal diffusion of SLNs delivered at different skin sites. The results showed that SLNs had excellent stability after being loaded into DMNs with no significant changes in morphology and fluorescence properties. The in vivo live and ex vivo imaging showed that the transdermal diffusion rate of NC-loaded DMNs was positively correlated with skin thickness, with the order ear > abdomen > back. In conclusion, this study confirmed the site-dependency of transdermal diffusion in NC-loaded DMNs.

Photoresponsive polymeric microneedles: An innovative way to monitor and treat diseases

Microneedles (MN) technology is an emerging technology for the transdermal delivery of therapeutics. When combined with photoresponsive (PR) materials, MNs can deliver therapeutics precisely and effectively with enhanced efficacy or synergistic effects. This review systematically summarizes the therapeutic applications of PRMNs in cancer therapy, wound healing, diabetes treatment, and diagnostics. Different PR approaches to activate and control the release of therapeutic agents from MNs are also discussed. Overall, PRMNs are a powerful tool for stimuli-responsive controlled-release therapeutic delivery to treat various diseases.

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.

Tacrolimus nanocrystals microneedle patch for plaque psoriasis

Plaque psoriasis is characterized by an abnormal thickening of the epidermis, which causes great difficulties for traditional topical drug delivery. Microneedles can pierce the thickened epidermis and deliver drugs to the skin for psoriasis treatment. Tacrolimus is a poorly water-soluble immunosuppressant used for the treatment of psoriasis. In this study, tacrolimus (TAC) nanocrystals (NCs) were produced using a bottom-up technique that dispersed TAC into a sodium hyaluronate-based microneedle patch (MNP), and its therapeutic efficacy was evaluated. The average particle size of the TAC NCs was 259.6 ± 2.3 nm. The mechanical strength of the microneedles was 0.41 ± 0.06 N/needle, which was sufficient to penetrate psoriatic skin. Microneedles were detached from the substrate 10 min after insertion into the psoriasis skin with an insertion depth of 258.8 ± 14.4 μm. The intradermal retention of the MNP (8.40 ± 0.33 μg/cm²) was six times that of the commercial ointment (1.40 ± 0.12 μg/cm²). In pharmacodynamic experiments, results indicated improvement in the phenotypic and histopathological features and reduction in the level of TNF-α, IL-17A, and IL-23 of psoriatic skin treated with TAC NCs MNP. Therefore, MNP loaded with TAC NCs may be a promising approach for psoriasis treatment.

Nanomaterial-Based Zinc Ion Interference Therapy to Combat Bacterial Infections

Pathogenic bacterial infections are the second highest cause of death worldwide and bring severe challenges to public healthcare. Antibiotic resistance makes it urgent to explore new antibacterial therapy. As an essential metal element in both humans and bacteria, zinc ions have various physiological and biochemical functions. They can stabilize the folded conformation of metalloproteins and participate in critical biochemical reactions, including DNA replication, transcription, translation, and signal transduction. Therefore, zinc deficiency would impair bacterial activity and inhibit the growth of bacteria. Interestingly, excess zinc ions also could cause oxidative stress to damage DNA, proteins, and lipids by inhibiting the function of respiratory enzymes to promote the formation of free radicals. Such dual characteristics endow zinc ions with unparalleled advantages in the direction of antibacterial therapy. Based on the fascinating features of zinc ions, nanomaterial-based zinc ion interference therapy emerges relying on the outstanding benefits of nanomaterials. Zinc ion interference therapy is divided into two classes: zinc overloading and zinc deprivation. In this review, we summarized the recent innovative zinc ion interference strategy for the treatment of bacterial infections and focused on analyzing the antibacterial mechanism of zinc overloading and zinc deprivation. Finally, we discuss the current limitations of zinc ion interference antibacterial therapy and put forward problems of clinical translation for zinc ion interference antibacterial therapy.

Hair follicle-targeting drug delivery strategies for the management of hair follicle-associated disorders

The hair follicle is not only a critical penetration route in percutaneous absorption but also has been recognized to be a target for hair follicle-associated disorders, such as androgenetic alopecia (AGA) and acne vulgaris. Hair follicle-targeting drug delivery systems allow for controlled drug release and enhance therapeutic efficacy with minimal side effects, exerting a promising method for the management of hair follicle-associated dysfunctions. Therefore, they have obtained much attention in several fields of research in recent years. This review gives an overview of potential follicle-targeting drug delivery formulations currently applied based on the particularities of the hair follicles, including a comprehensive assessment of their preclinical and clinical performance.