Dissolving Microneedles with Spatiotemporally controlled pulsatile release Nanosystem for Synergistic Chemo-photothermal Therapy of Melanoma

Cyclosporin A-loaded dissolving microneedles for dermatitis therapy: Development, characterisation and efficacy in a delayed-type hypersensitivity in vivo model

Several drugs can be used for treating inflammatory skin pathologies like dermatitis and psoriasis. However, for the management of chronic and long-term cases, topical administration is preferred over oral delivery since it prevents certain issues due to systemic side effects from occurring. Cyclosporin A (CsA) has been used for this purpose; however, its high molecular weight (1202 Da) restricts the diffusion through the skin structure. Here, we developed a nano-in-micro device combining lipid vesicles (LVs) and dissolving microneedle array patches (DMAPs) for targeted skin delivery. CsA-LVs allowed the effective incorporation of CsA in the hydrophilic DMAP matrix despite the hydrophobicity of the drug. Polymeric matrix composed of poly (vinyl alcohol) (5% w/v), poly (vinyl pyrrolidine) (15% w/v) and CsA-LV dispersion (10% v/v) led to the formation of CsA-LVs@DMAPs with adequate mechanical properties to penetrate the stratum corneum barrier. The safety and biocompatibility were ensured in an in vitro viability test using HaCaT keratinocytes and L929 fibroblast cell lines. Ex vivo permeability studies in a Franz-diffusion cell setup showed effective drug retention in the skin structure. Finally, CsA-LVs@DMAPs were challenged in an in vivo murine model of delayed-type hypersensitivity to corroborate their potential to ameliorate skin inflammatory conditions. Different findings like photon emission reduction in bioluminescence study, normalisation of histological damage and decrease of inflammatory cytokines point out the effectivity of CsA-LVs@DMAPs to treat these conditions. Overall, our study demonstrates that CsA-LVs@DMAPs can downregulate the skin inflammatory environment which paves the way for their clinical translation and their use as an alternative to corticosteroid-based therapies.

Reconnoitring signaling pathways and exploiting innovative approaches tailoring multifaceted therapies for skin cancer

Nowadays, skin cancer is widespread just like a varied malignant cancer which can cause serious health issues. Skin cancer, which encompasses malignant melanoma, basal cell carcinoma, and squamous cell carcinoma, is a prevalent form of cancer among humans. Due to its broad prevalence, financial burden, mortality rates, and cosmetic effects, it is a major public health issue. Skin cancer treatment involves surgery, chemotherapy, and radiation. Recently, personalized treatment in the fields of targeted therapies and precision medicine has been shown to diagnose early detection of every individual tumor by knowing their genetic and molecular characteristics. To target the molecular pathways responsible for tumor growth and reduce the damage to healthy tissue, new targeted therapies have emerged for melanoma, basal cell carcinoma, and squamous cell carcinoma. B-raf serine/threonine kinase (BRAF) and mitogen-activated protein kinase (MEK) inhibitors, immune checkpoint inhibitors, and precision medications have strong response rates to improve patient survival. Targeted therapeutics like nanocarriers have shown promising results by reducing skin irritation and protecting encapsulated therapeutics. These formulations have been shown to improve the transdermal permeability of anticancer drugs. The consideration of employing physical techniques to enhance the permeation of nanocarriers warrants attention to augment the dermal permeation of anticancer agents and facilitate targeted drug delivery within neoplastic cells. Targeted therapies face obstacles like resistance mechanisms and treatment strategy monitoring. Taken together, this review delves into the basic mechanisms of skin cancer, current treatment methods, drug resistance processes, and nano-based targeted techniques for cancer treatment. It will also delineate the challenges and perspectives in pre-clinical and clinical contexts.

Microneedles as an Emerging Platform for Transdermal Delivery of Phytochemicals

Phytochemicals, which are predominantly found in plants, hold substantial medicinal value. Despite their potential, challenges such as poor oral bioavailability and instability in the gastrointestinal tract have limited their therapeutic use. Traditional intra/transdermal drug delivery systems offer some advantages over oral administration but still suffer from issues such as limited penetration depth, slow drug release rates, and inconsistent drug absorption. In contrast, microneedles (MNs) represent a significant advancement in intra/transdermal drug delivery by providing precise control over phytochemical delivery and enhanced penetration capabilities. By circumventing skin barriers, MNs directly access dermal layers rich in blood vessels and lymphatics, thus facilitating efficient phytochemical delivery. This review extensively discusses the obstacles of traditional oral delivery and the benefits of intra/transdermal delivery routes with a particular focus on the transformative potential of MNs for phytochemical delivery. This review explores the complexities of delivering phytochemicals through intra/transdermal routes, the development and types of MNs as innovative delivery tools, and the optimal design and properties of MNs for effective phytochemical delivery. Additionally, this review examines the versatile applications of MN-mediated phytochemical delivery, including its role in administering phytophotosensitizers for photodynamic therapy, and concludes with insights into relevant patents and future perspectives.

Dissolving microneedles: standing out in melanoma treatment

Melanoma is one of the most significant and dangerous superficial skin tumors with a high fatality rate, thanks to its high invasion rate, drug resistance and frequent metastasis properties. Unfortunately, researchers for decades have demonstrated that the outcome of using conventional therapies like chemotherapy and immunotherapy with normal drug delivery routes, such as an oral route to treat melanoma was not satisfactory. The severe adverse effects, slow drug delivery efficiency and low drug accumulation at targeted malignancy sites all lead to poor anti-cancer efficacy and terrible treatment experience. As a novel transdermal drug delivery system, microneedles (MNs) have emerged as an effective solution to help improve the low cure rate of melanoma. The excellent characteristics of MNs make it easy to penetrate the stratum corneum (SC) and then locally deliver the drug towards the lesion without drug leakage to mitigate the occurrence of side effects and increase the drug accumulation. Therefore, loading chemotherapeutic drugs or immunotherapy drugs in MNs can address the problems mentioned above, and MNs play a crucial role in improving the curative effect of conventional treatment methods. Notably, novel tumor therapies like photothermal therapy (PTT), photodynamic therapy (PDT) and chemodynamic therapy (CDT) have shown good application prospects in the treatment of melanoma, and MNs provide a valid platform for the combination of conventional therapies and novel therapies by encompassing different therapeutic materials in the matrix of MNs. The synergistic effect of multiple therapies can enhance the therapeutic efficacy compared to single therapies, showing great potential in melanoma treatment. Dissolving MNs have been the most commonly used microneedles in the treatment of melanoma in recent years, mainly because of their simple fabrication procedure and enough drug loading. So, considering the increasing use of dissolving MNs, this review collects research studies published in the last four years (2020-2024) that have rarely been included in other reviews to update the progress of applications of dissolving MNs in anti-melanoma treatment, especially in synergistic therapies. This review also presents current design and fabrication methods of dissolving MNs; the limitations of microneedle technology in the treatment of melanoma are comprehensively discussed. This review can provide valuable guidance for their future development.

Nanotechnology-Based Drug Delivery Systems for Treating Acute Kidney Injury

Acute kidney injury (AKI) is a disease that is characterized by a rapid decline in renal function and has a relatively high incidence in hospitalized patients. Sepsis, renal hypoperfusion, and nephrotoxic drug exposure are the main causes of AKI. The major therapy measures currently include supportive treatment, symptomatic treatment, and kidney transplantation. These methods are supportive treatments, and their results are not satisfactory. Fortunately, many new treatments that markedly improve the AKI therapy efficiency are emerging. These include antioxidant therapy, ferroptosis therapy, anti-inflammatory therapy, autophagy therapy, and antiapoptotic therapy. In addition, the development of nanotechnology has further promoted therapeutic effects on AKI. In this review, we highlight recent advances in the development of nanocarriers for AKI drug delivery. Emphasis has been placed on the latest developments in nanocarrier modification and design. We also summarize the applications of different nanocarriers in AKI treatment. Finally, the advantages and challenges of nanocarrier applications in AKI are summarized, and several nanomedicines that have been approved for clinical trials to treat diverse kidney diseases are listed.

Microneedles with Implantable Tip-Accumulated Therapeutics for the Long-Term Management of Psoriasis

Methotrexate is successfully used as the gold standard for managing moderate-to-severe psoriasis. However, the low bioavailability and short half-life of the oral pills and the invasiveness of the parenteral injections make these suboptimal therapeutic options. Microneedles, bridging the advantages of the former forms, are successfully used to deliver methotrexate for different therapeutic purposes. However, the utilized dissolving microneedles demand frequent administration, potentially compromising patients' compliance. Additionally, the high toxicity of methotrexate prompts a quest for safer alternatives. Phloretin, a natural compound with confirmed antipsoriatic potential, emerges as a promising candidate. Herein, microneedle patches with separable, slow-degrading tips are developed for the sustained delivery of methotrexate and phloretin, as a comprehensive solution for long-term psoriasis management. Both compounds are individually loaded at varying doses and display sustained-release profiles. The developed microneedle patches demonstrate high mechanical strength, favorable drug delivery efficiency, and remarkable antipsoriatic potential both in vitro in keratinocytes and in vivo in a psoriasis mouse model. Comparative analysis with two subcutaneous injections reveals a similar antipsoriatic efficacy with a single patch of either compound, with prominent phloretin safety. Therefore, the developed patches present a superior alternative to methotrexate's current marketed forms and provide a viable alternative (phloretin) with comparable antipsoriatic efficacy and higher safety.

Biomineralized in situ catalytic nanoreactor integrated microneedle patch for on demand immunomodulator supply to combat psoriasis

The endogenous immunomodulator adenosine (ADO) was expected to be potentialized as an efficacious mediator to combat psoriasis. However, its efficacy is severely hindered by its poor metabolic stability and insufficient accumulation at the dermatological lesions. Methods: In this study, a biomineralized in situ catalytic nanoreactor was delicately customized by encapsulating ADO precursor (adenosine monophosphate, AMP) within the internal porous skeleton of zeolitic imidazolate framework-90, followed by the biomineralization of the AMP catabolic enzyme on the outer layer. The nanocrystals were then incorporated into a dissolving microneedles patch, which was designed to deliver drugs with precision into the cutaneous lesion and enhance the efficacy of psoriasis treatment. Results: Upon penetration into the skin, the nanoreactors were released and underwent a gradual collapse of their structure, releasing AMP when exposed to the acidic microenvironment. Meanwhile, the acidic pH could trigger an in situ catalytic reaction to continuously produce ADO. This system yielded remarkable results in a psoriasis-like mouse model. The mechanism study demonstrated that this system could substantially reshape the inflammatory ecosystem by inhibiting the keratinocyte hyperplasia, reducing inflammatory cytokine expression, and regulating the infiltration of immune cells. Conclusion: The in situ catalytic nanoreactor integrated microneedle patch is a promising modular platform for co-delivery of prodrugs and their catabolic enzymes, offering a potential solution for various diseases.

Development of Quercetin Solid Dispersion-Loaded Dissolving Microneedles and In Vitro Investigation of Their Anti-Melanoma Activities

Background: Melanoma is a skin cancer that requires early treatment to prevent metastasis. In particular, the superficial spreading melanoma, excisional surgery with local administration of anti-cancer drugs via microneedles is currently considered a potential combination therapy. Quercetin is a natural flavonoid having activities against melanoma cells. Unfortunately, the therapeutic effect is limited by its poor water solubility. Objectives: This study aimed to develop formulations of solid dispersion-loaded dissolving microneedles (SD-DMNs) of quercetin and to investigate their in vitro activities against melanoma cells. Methods: Quercetin solid dispersions (Q-SDs) were prepared using polyvinylpyrrolidone K30 (PVP) via a solvent technique. The optimized Q-SD was selected for preparing Q-SD-loaded dissolving microneedles (Q-SD-DMNs) using a mold casting method. Results: Q-SDs had higher water solubility than that of quercetin by 5-10 times depending on the ratio of quercetin-to-PVP. The presence of quercetin in the Q-SD and Q-SD-DMN were in an amorphous form. The obtained Q-SD-DMNs had pyramid-shaped microneedles. Their strength depended on the compositions, i.e., ratios of hyaluronic acid-to-sodium carboxymethylcellulose and the content of Q-SD. An optimized Q-SD-DMN increased the in vitro skin permeation of quercetin compared to that of microneedles containing quercetin (without being processed). From the molecular investigations, the optimized Q-SD-DMN reduced the viability of the A375 cells (melanoma cells) through the induction of cell apoptosis. It suppressed Bcl-2 gene expression and led to a lower content of Bcl-2 in the cells. Conclusions: The optimized Q-SD-DMN has a potential for use in further in vivo studies as a synergistic method of melanoma treatment.

Biological Fate Tracking of Nitric Oxide-Propelled Microneedle Delivery System Using an Aggregation-Caused Quenching Probe

Nanoparticle-loaded dissolving microneedles (DMNs) have attracted increasing attention due to their ability to provide high drug loading, adjustable drug release behavior, and enhanced therapeutic efficiency. However, such delivery systems still face unsatisfied drug delivery efficiency due to insufficient driving force to promote nanoparticle penetration and the lack of in vivo fate studies to guide formulation design. Herein, an aggregation-caused quenching (ACQ) probe (P4) was encapsulated in l-arginine (l-Arg)-based nanomicelles, which was further formulated into nitric oxide (NO)-propelled nanomicelle-integrated DMNs (P4/l-Arg NMs@DMNs) to investigate their biological fate. The P4 probe could emit intense fluorescence signals in intact nanomicelles, while quenching with the dissociation of nanomicelles, providing a "distinguishable" method for tracking the fate of nanomicelles at a different status. l-Arg was demonstrated to self-generate NO under the tumor microenvironment with excessive reactive oxygen species (ROS), providing a pneumatic force to promote the penetration of nanomicelles in both three-dimensional (3D)-cultured tumor cells and melanoma-bearing mice. Compared with passive microneedles (P4 NMs@DMNs) without a NO propellant, the P4/l-Arg NMs@DMNs possessed a good NO production performance and higher nanoparticle penetration capacity. In conclusion, this study offered an ACQ probe-based biological fate tracking approach to demonstrate the potential of NO-propelled nanoparticle-loaded DMNs in penetration enhancement for topical tumor therapy.

Evodiamine encapsulated by hyaluronic acid modified zeolitic imidazolate framework-8 for tumor targeted therapy

Evodiamine (EVO), a natural bioactive compound extracted from Evodia rutaecarpa, shows therapeutic ability against malignant melanoma. However, the poor solubility and bioavailability of EVO limit its clinical application. Metal-organic frameworks (MOFs) have shown excellent physical and chemical properties and are widely used as drug delivery systems. Among them, zeolitic imidazolate framework-8 (ZIF-8) is a research popular material because of its unique properties, such as hydrothermal stability, non-toxicity, biocompatibility, and pH sensitivity. In this study, in order to load EVO, a drug carrier that hyaluronic acid (HA) modified zeolitic imidazolate framework-8 (ZIF-8) is synthesized. This drug carrier has shown drug loading with 6.2 ± 0.6%, and the nano drugs (EVO@ZIF-8/HA) have good dispersibility. Owing to the decoration HA of EVO@ZIF-8, the potential of the nano drugs is reversed from the positive charge to the negative charge, which is beneficial to blood circulation in vivo. Furthermore, because the CD44-expressing in tumor cells is excessed, the endocytosis and accumulation of nano drugs in tumor cells are beneficial to improvement. Compared with free EVO, EVO@ZIF-8/HA has shown a significantly improved anti-tumor efficacy in vitro and in vivo. In summary, the drug carrier effectively addresses the challenges that are caused by the strong hydrophobicity and low bioavailability of EVO, thereby targeted tumor therapy of EVO can be achieved.

A Novel Multi-Effect Photosensitizer for Tumor Destruction via Multimodal Imaging Guided Synergistic Cancer Phototherapy

Background

How to ingeniously design multi-effect photosensitizers (PSs), including multimodal imaging and multi-channel therapy, is of great significance for highly spatiotemporal controllable precise phototherapy of malignant tumors.

Methods

Herein, a novel multifunctional zinc(II) phthalocyanine-based planar micromolecule amphiphile (ZnPc 1) was successfully designed and synthesized, in which N atom with photoinduced electron transfer effect was introduced to enhance the near-infrared absorbance and nonradiative heat generation. After simple self-assembling into nanoparticles (NPs), ZnPc 1 NPs would exhibit enhanced multimodal imaging properties including fluorescence (FL) imaging (FLI) /photoacoustic (PA) imaging (PAI) /infrared (IR) thermal imaging, which was further used to guide the combined photodynamic therapy (PDT) and photothermal therapy (PTT).

Results

It was that under the self-guidance of the multimodal imaging, ZnPc 1 NPs could precisely pinpoint the tumor from the vertical and horizontal boundaries achieving highly efficient and accurate treatment of cancer.

Conclusion

Accordingly, the integration of FL/PA/IR multimodal imaging and PDT/PTT synergistic therapy pathway into one ZnPc 1 could provide a blueprint for the next generation of phototherapy, which offered a new paradigm for the integration of diagnosis and treatment in tumor and a promising prospect for precise cancer therapy.

Development of Intratumoral Drug Delivery Based Strategies for Antitumor Therapy

Research for tumor treatment with significant therapy effects and minimal side-effects has been widely carried over the past few decades. Different drug forms have received a lot of attention. However, systemic biodistribution induces efficacy and safety issues. Intratumoral delivery of agents might overcome these problems because of its abundant tumor accumulation and retention, thereby reducing side effects. Delivering hydrogels, nanoparticles, microneedles, and microspheres drug carriers directly to tumors can realize not only targeted tumor therapy but also low side-effects. Furthermore, intratumoral administration has been integrated with treatment strategies such as chemotherapy, enhancing radiotherapy, immunotherapy, phototherapy, magnetic fluid hyperthermia, and multimodal therapy. Some of these strategies are ongoing clinical trials or applied clinically. However, many barriers hinder it from being an ideal and widely used option, such as decreased drug penetration impeded by collagen fibers of a tumor, drug squeezed out by high density and high pressure, mature intratumoral injection technique. In this review, we systematically discuss intratumoral delivery of different drug carriers and current development of intratumoral therapy strategies.

Boosting Checkpoint Immunotherapy with Biomimetic Nanodrug Delivery Systems

Immune checkpoint blockade (ICB) has achieved unprecedented progress in tumor immunotherapy by blocking specific immune checkpoint molecules. However, the high biodistribution of the drug prevents it from specifically targeting tumor tissues, leading to immune-related adverse events. Biomimetic nanodrug delivery systems (BNDSs) readily applicable to ICB therapy have been widely developed at the preclinical stage to avoid immune-related adverse events. By exploiting or mimicking complex biological structures, the constructed BNDS as a novel drug delivery system has good biocompatibility and certain tumor-targeting properties. Herein, the latest findings regarding the aforementioned therapies associated with ICB therapy are highlighted. Simultaneously, prospective bioinspired engineering strategies can be designed to overcome the four-level barriers to drug entry into lesion sites. In future clinical translation, BNDS-based ICB combination therapy represents a promising avenue for cancer treatment.

Spatiotemporal fate of nanocarriers-embedded dissolving microneedles: the impact of needle dissolving rate

OBJECTIVE

Dissolving microneedles (DMNs) have shown great potential for transdermal drug delivery due to their excellent skin-penetrating ability and combination with nanocarriers (NCs) can realize targeted drug delivery. The objective of this study was to investigate the impact of microneedle dissolving rate on the in vivo fate of NC-loaded DMNs, which would facilitate the clinical translation of such systems.

METHODS

Solid lipid nanoparticles (SLNs) were selected as the model NC for loading in DMNs, which were labeled by P4 probes with aggregation-quenching properties. Sodium hyaluronate acid (HA) and chitosan (CS), with different aqueous dissolving rates, were chosen as model tip materials. The effects of needle dissolving rate on the in vivo fate of NC-loaded DMNs was investigated by tracking the distribution of fluorescence signals after transdermal exposure.

RESULTS

P4 SLNs achieved a deeper diffusion depth of 180 μm in DMN-HA with a faster dissolution rate, while the diffusion depth in DMN-CS with a slower dissolution rate was lower (140 μm). The in vivo experiments demonstrated that P4 SLNs had a T1/2 value of 12.14 h in DMN-HA, whilst a longer retention time was found in DMN-CS, with a T1/2 of 13.12 h.

CONCLUSIONS

This study confirmed that the in vivo diffusion rate of NC-loaded DMNs was determined by the dissolving rate of DMNs materials and provided valuable guidance for the design and development of NC-loaded DMNs in the future.

ATP-adenosine axis regulation combined with microneedle assisted photoimmunotherapy to boost the immunotherapy efficiency

Immunogenic cell death (ICD) is associated with the release of damage-associated molecular patterns, including ATP, to promote an effective immune cycle against tumors. However, tumors have evolved an effective strategy for degrading extracellular immunostimulatory ATP via the ATP-adenosine axis, allowing the sequential action of the ectonucleotidases CD39 to degrade accumulated immunostimulatory ATP into pleiotropic immunosuppressive adenosine. Here, an ingenious dissolving microneedle patch (DMNs) is designed for the intralesional delivery of CD39 inhibitor (sodium polyoxotungstate, POM-1) and ICD inducer (IR780) co-encapsulated solid lipid nanoparticles (P/I SLNs) for antitumor therapy. Upon insertion into the tumor site, IR780 induces ICD modalities with the release of damage-associated molecular patterns from endogenous tissues, which activates the antitumor immune cycle. Simultaneously, POM-1 promotes the liberation of immunostimulatory ATP and lowers the level of immunosuppressive extracellular adenosine, which supported immune control of tumors via recruiting CD39-expressing immune cells. In vivo antitumor studies prove that this platform can effectively eliminate mice melanoma (tumor growth inhibitory rate of 96.5%) and colorectal adenocarcinoma (tumor growth inhibitory rate of 93.5%). Our results shed light on the immunological aspects of combinatorial phototherapy and ATP-adenosine regulation, which will broaden the scope of synergistic antitumor immunotherapy.

The Necessity to Investigate In Vivo Fate of Nanoparticle-Loaded Dissolving Microneedles

Transdermal drug delivery systems are rapidly gaining prominence and have found widespread application in the treatment of numerous diseases. However, they encounter the challenge of a low transdermal absorption rate. Microneedles can overcome the stratum corneum barrier to enhance the transdermal absorption rate. Among various types of microneedles, nanoparticle-loaded dissolving microneedles (DMNs) present a unique combination of advantages, leveraging the strengths of DMNs (high payload, good mechanical properties, and easy fabrication) and nanocarriers (satisfactory solubilization capacity and a controlled release profile). Consequently, they hold considerable clinical application potential in the precision medicine era. Despite this promise, no nanoparticle-loaded DMN products have been approved thus far. The lack of understanding regarding their in vivo fate represents a critical bottleneck impeding the clinical translation of relevant products. This review aims to elucidate the current research status of the in vivo fate of nanoparticle-loaded DMNs and elaborate the necessity to investigate the in vivo fate of nanoparticle-loaded DMNs from diverse aspects. Furthermore, it offers insights into potential entry points for research into the in vivo fate of nanoparticle-loaded DMNs, aiming to foster further advancements in this field.

Drug Delivery Systems based on Microneedles for Dermatological Diseases and Aesthetic Enhancement

Microneedle (MN) devices comprise of micron-sized structures that circumvent biological barriers in a minimally invasive manner. MN research continues to grow and evolve; the technology was recently identified as one of the top ten overall emerging technologies of 2020. There is a growing interest in using such devices in cosmetology and dermatological conditions where the MNs mechanically disrupt the outer skin barrier layer, creating transient pathways that allow the passage of materials to underlying skin layers. This review aims to appraise the application of microneedle technologies in skin science, provide information on potential clinical benefits, as well as indicate possible dermatological conditions that can benefit from this technology, including autoimmunemediated inflammatory skin diseases, skin aging, hyperpigmentation, and skin tumors. A literature review was carried out to select studies that evaluated the use of microneedles to enhance drug delivery for dermatologic purposes. MN patches create temporary pathways that allow the passage of therapeutic material to deeper layers of the skin. Given their demonstrable promise in therapeutic applications it will be essential for healthcare professionals to engage with these new delivery systems as they transition to the clinic.

Cubosomes-assisted transdermal delivery of doxorubicin and indocyanine green for chemo-photothermal combination therapy of melanoma

Melanoma is a highly aggressive form of skin cancer with limited therapeutic options. Chemo-photothermal combination therapy has demonstrated potential for effectively treating melanoma, and transdermal administration is considered the optimal route for treating skin diseases due to its ability to bypass first-pass metabolism and enhance drug concentration. However, the stratum corneum presents a formidable challenge as a significant barrier to drug penetration in transdermal drug delivery. Lipid-nanocarriers, particularly cubosomes, have been demonstrated to possess significant potential in augmenting drug permeation across the stratum corneum. Herein, cubosomes co-loaded with doxorubicin (DOX, a chemotherapeutic drug) and indocyanine green (ICG, a photothermal agent) (DOX-ICG-cubo) transdermal drug delivery system was developed to enhance the therapeutic efficiency of melanoma by improving drug permeation. The DOX-ICG-cubo showed high encapsulation efficiency of both DOX and ICG, and exhibited good stability under physiological conditions. In addition, the unique cubic structure of the DOX-ICG-cubo was confirmed through transmission electron microscopy (TEM) images, polarizing microscopy, and small angle X-ray scattering (SAXS). The DOX-ICG-cubo presented high photothermal conversion efficiency, as well as pH and thermo-responsive DOX release. Notably, the DOX-ICG-cubo exhibited enhanced drug permeation efficiency, good biocompatibility, and improved in vivo anti-melanoma efficacy through the synergistic effects of chemo-photothermal therapy. In conclusion, DOX-ICG-cubo presented a promising strategy for melanoma treatment.

Steerable Microneedles Enabling Deep Delivery of Photosensitizers and CRISPR/Cas9 Systems for Effective Combination Cancer Therapy

Although gene therapy has shown prospects in treating triple-negative breast cancer, it is insufficient to treat such a malignant tumor. Herein, nanoparticles (NPs)-embedded dissolving microneedles (IR780-PL/pFBXO44@MNs) with steerable and flectional property were developed to achieve the codelivery of FBXO44-targeted CRISPR/Cas9 plasmids (pFBXO44) and hydrophobic photosensitizers. For improved NP penetration in tumor tissue, collagenase@MNs were preapplied to degrade the tumor matrix. Under light irradiation, IR780 exhibited remarkable phototherapy, while the escape efficiency of NPs from lysosomes was improved. pFBXO44 was subsequently released in tumor cell cytoplasm via reducing the disulfide bonds of NPs, which could specifically knock out the FBXO44 gene to inhibit the migration and invasion of tumor cells. As a result, tumor cells were eradicated, and lung metastasis was effectively suppressed. This micelle-incorporated microneedle platform broadens the potential of combining gene editing and photo synergistic cancer therapy.

Microneedle-Mediated Transcutaneous Immunization: Potential in Nucleic Acid Vaccination

Efforts aimed at exploring economical and efficient vaccination have taken center stage to combat frequent epidemics worldwide. Various vaccines have been developed for infectious diseases, among which nucleic acid vaccines have attracted much attention from researchers due to their design flexibility and wide application. However, the lack of an efficient delivery system considerably limits the clinical translation of nucleic acid vaccines. As mass vaccinations via syringes are limited by low patient compliance and high costs, microneedles (MNs), which can achieve painless, cost-effective, and efficient drug delivery, can provide an ideal vaccination strategy. The MNs can break through the stratum corneum barrier in the skin and deliver vaccines to the immune cell-rich epidermis and dermis. In addition, the feasibility of MN-mediated vaccination is demonstrated in both preclinical and clinical studies and has tremendous potential for the delivery of nucleic acid vaccines. In this work, the current status of research on MN vaccines is reviewed. Moreover, the improvements of MN-mediated nucleic acid vaccination are summarized and the challenges of its clinical translation in the future are discussed.

A self-monitoring microneedle patch for light-controlled synergistic treatment of melanoma

Melanoma is the most aggressive and malignant form of skin cancer. Current melanoma treatment methods generally suffer from frequent drug administration as well as difficulty in direct monitoring of drug release. Here, a self-monitoring microneedle (MN)-based drug delivery system, which integrates a dissolving MN patch with aggregation-induced emission (AIE)-active PATC microparticles, is designed to achieve light-controlled pulsatile chemo-photothermal synergistic therapy of melanoma. The PATC polymeric particles, termed D/I@PATC, encapsulate both of chemotherapeutic drug doxorubicin (DOX) and the photothermal agent indocyanine green (ICG). Upon light illumination, PATC gradually dissociates into smaller particles, causing the release of encapsulated DOX and subsequent fluorescence intensity change of PATC particles, thereby not only enabling direct observation of the drug release process under light stimuli, but also facilitating verification of drug release by fluorescence recovery after light trigger. Moreover, encapsulation of ICG in PATC particles displays significant improvement of its photothermal stability both in vitro and in vivo. In a tumor-bearing mouse, the application of one D/I@PATC MN patch combining with two cycles of light irradiation showed excellent controllable chemo-photothermal efficacy and exhibited ∼97% melanoma inhibition rate without inducing any evident systemic toxicity, suggesting a great potential for skin cancer treatment in clinics.

Combinational photodynamic and photothermal - based therapies for melanoma in mouse models

BACKGROUND

Melanoma is a highly metastatic skin cancer with limited response to current therapies in advanced patients. To overcome resistance, novel treatments based on photodynamic and photothermal therapies (PDT and PTT, respectively) have been developed to treat melanoma in preclinical murine models. Despite success inhibiting implanted tumors' growth, there has been limited evaluation of their long-term effectiveness in preventing metastasis, recurrence, or improving survival rates.

METHODS

Combined and multidrug therapies based on PDT and/or PTT to treat cutaneous malignant melanoma in the preclinical mouse model were reviewed from 2016 onwards. PubMed® was the database in which the search was performed using mesh search algorithms resulting in fifty-one studies that comply with strict inclusion rules of screening.

RESULTS

B16 melanoma-bearing C57BLACK6 mice model was the most used to evaluate immunotherapies, chemotherapies, and targeted therapies in combination with PDT and/or PTT. Combined therapies demonstrated a synergistic effect, resulting in intense antitumor activity. The most extensively studied protocol for developing metastatic models involved the intravenous administration of malignant cells, with some combined therapies being tested. Furthermore, the review presents the composition of the nanostructures utilized for delivering the drugs and light-responsive agents and the treatment plans for each combined approach.

CONCLUSIONS

The identified mechanisms to simulate metastatic melanoma models and the therapeutic combinations may aid in evaluating the systemic protection of combined PDT and PTT-based therapies, particularly in conducting short-term preclinical experiments. Such simulations could have relevance to clinical studies.

Microneedle-mediated treatment for superficial tumors by combining multiple strategies

Superficial tumors are still challenging to overcome due to the high risk and toxicity of surgery and conventional chemotherapy. Microneedles (MNs) are widely used in the treatment of superficial skin tumors (SST) due to the high penetration rate of the stratum corneum (SC), excellent biocompatibility, simple preparation process, high patient compliance, and minimal invasion. Most importantly, MNs can provide not only efficient and rarely painful delivery carriers, but also combine multi-model strategies with photothermal therapy (PTT), immunotherapy, and gene therapy for synergistic efficacy. To promote an in-depth understanding of their superiorities, this paper systematically summarized the latest application progress of MNs in the treatment of SST by delivering various types of photosensitizers, immune signal molecules, genes, and chemotherapy drugs. Just as important, the advantages, limitations, and drug release mechanisms of MNs based on different materials are introduced in the paper. In addition, the application of MN technology to clinical practice is the ultimate goal of all the work. The obstacles and possible difficulties in expanding the production of MNs and achieving clinical transformation are briefly discussed in this paper. To be anticipated, our work will provide new insights into the precise and rarely painful treatment of SST in the future.

A Scalable Platform for Fabricating Biodegradable Microparticles with Pulsatile Drug Release

Pulsatile drug delivery systems have the potential to improve patient adherence and therapeutic efficacy by providing a sequence of doses in a single injection. Herein, a novel platform, termed Particles Uniformly Liquified and Sealed to Encapsulate Drugs (PULSED) is developed, which enables the high-throughput fabrication of microparticles exhibiting pulsatile release. In PULSED, biodegradable polymeric microstructures with an open cavity are formed using high-resolution 3D printing and soft lithography, filled with drug, and sealed using a contactless heating step in which the polymer flows over the orifice to form a complete shell around a drug-loaded core. Poly(lactic-co-glycolic acid) particles with this structure can rapidly release encapsulated material after delays of 10 ± 1, 15 ± 1, 17 ± 2, or 36 ± 1 days in vivo, depending on polymer molecular weight and end group. The system is even compatible with biologics, releasing over 90% of bevacizumab in its bioactive form after a two-week delay in vitro. The PULSED system is highly versatile, offering compatibility with crystalline and amorphous polymers, easily injectable particle sizes, and compatibility with several newly developed drug loading methods. Together, these results suggest that PULSED is a promising platform for creating long-acting drug formulations that improve patient outcomes due to its simplicity, low cost, and scalability.

Microneedle patches containing mesoporous polydopamine nanoparticles loaded with triamcinolone acetonide for the treatment of oral mucositis

Oral mucositis (OM) is the most common disease of the oral mucosa, which affects people's daily production and life. Triamcinolone ointment is the common clinical drug for OM treatment. However, the hydrophobic properties of triamcinolone acetonide (TA) and the complex microenvironment of the oral cavity led to its low bioavailability and unstable therapeutic effects on ulcer wounds. Herein, dissolving microneedle patches (MNs) composed of mesoporous polydopamine nanoparticles (MPDA) loaded with TA (TA@MPDA), sodium hyaluronic acid (HA), and Bletilla striata polysaccharide (BSP) are prepared as the transmucosal delivery system. The prepared TA@MPDA-HA/BSP MNs exhibit well-arranged microarrays, high mechanical strength and fast solubility (<3 min) properties. In addition, the hybrid structure improves the biocompatibility of TA@MPDA and expedites oral ulcer healing in the SD rat model through the synergistic anti-inflammatory and pro-healing effects of microneedle ingredients (hormones, MPDA and Chinese herbs extracts), with 90% less amount of TA compared with Ning Zhi Zhu^®. TA@MPDA-HA/BSP MNs are shown to be their great potential as novel ulcer dressings for OM management.

Photobiomodulation: A Systematic Review of the Oncologic Safety of Low-Level Light Therapy for Aesthetic Skin Rejuvenation

Photobiomodulation (PBM) therapy is an increasingly popular modality for aesthetic skin rejuvenation. PBM induces genomic, proteomic, and metabolomic processes within target cells, but such manipulation of cell behavior has led to concerns about oncologic safety. This article presents a summary of the clinical and preclinical evidence for the oncologic safety of PBM for aesthetic skin rejuvenation. A focused systematic review was performed, in which safety data from clinical trials of PBM for skin rejuvenation was supplemented by analyses of in vitro data obtained from cells derived from human skin and human neoplastic cells and in vivo data of tumors of the skin, oral cavity, and breast. Within established parameters, red and near infrared light mainly enhances proliferation of healthy cells without a clear pattern of influence on cell viability. The same light parameters mainly reduce neoplastic cell proliferation and viability or else make no difference. Invasiveness potential (appraised by cell migration assays and/or differential gene expression) is equivocal. PBM does not induce dysplastic change in healthy cells. In vivo tumor models yield varied results with no clear pattern emerging. There are no relevant clinical trial data linking PBM with any significant adverse events, including the finding of a new or recurrent malignancy.Current clinical and preclinical evidence suggests that PBM is oncologically safe for skin rejuvenation, and there is no evidence to support the proposition that it should be avoided by patients who have previously undergone treatment for cancer.

LEVEL OF EVIDENCE: 4

Nanodelivery systems for cutaneous melanoma treatment

Cutaneous melanoma (CM) is a multifactorial disease whose treatment still presents challenges: the rapid progression to advanced CM, which leads to frequent recurrences even after surgical excision and, notably, the low response rates and resistance to the available therapies, particularly in the case of unresectable metastatic CM. Thereby, alternative innovative therapeutic approaches for CM continue to be searched. In this review we discuss relevant preclinical research studies, and provide a broad-brush analysis of patents and clinical trials which involve the application of nanotechnology-based delivery systems in CM therapy. Nanodelivery systems have been developed for the delivery of anticancer biomolecules to CM, which can be administered by different routes. Overall, nanosystems could promote technological advances in several therapeutic modalities and can be used in combinatorial therapies. Nevertheless, the results of these preclinical studies have not been translated to clinical applications. Thus, concerted and collaborative research studies involving basic, applied, translational, and clinical scientists need to be performed to allow the development of effective and safe nanomedicines to treat CM.

NIR light-activatable dissolving microneedle system for melanoma ablation enabled by a combination of ROS-responsive chemotherapy and phototherapy

BACKGROUND

As a consequence of the aggressive and recurrent nature of melanoma, repeated, multimodal treatments are often necessary to cure the disease. While microneedle (MN)-based transdermal drug delivery methods can allow drugs to avoid first-pass metabolism and overcome the stratum corneum barrier, the main challenges of these delivery methods entail the lack of controlled drug release/activation and effective imaging methods to guide the entire treatment process.

METHODS

To enable a transdermal delivery method with controllable drug release/activation and effective imaging guidance, we designed a near-infrared (NIR) photoactivatable, dissolving MN system comprising dissolvable polyvinylpyrrolidone MNs arrays (MN-pB/I) containing liposomes that were co-loaded with the photosensitizer indocyanine green (ICG) and the reactive oxygen species (ROS)-activatable prodrug of doxorubicin (pB-DOX).

RESULTS

After applying the MN patch to the tumor site, the liposomes concentrated in the needle tips were released into the tumor tissue and distributed evenly upon dissolution of the matrix to enable targeted delivery. Then, the ROS produced by ICG after exposure to NIR light performed photodynamic therapy and activated the pB-DOX for chemotherapy by cleaving the prodrug moiety and converting it to DOX. As a dye, ICG was also used to guide the treatment regimens and monitor the efficacy by fluorescence and photoacoustic imaging. The growth of the tumors in the MN-pB/I group were inhibited by 93.5%, while those were only partially inhibited in the control groups. Negligible treatment-induced side effects and cardiotoxicity were observed.

CONCLUSION

The MN-pB/I represents a multimodal, biocompatible theragnostic system with spatiotemporal control that was capable of ablating melanoma tumors after a single dose, providing a promising candidate for clinical melanoma therapy.

Advancements in nanoparticle-based treatment approaches for skin cancer therapy

Skin cancer has emerged as the fifth most commonly reported cancer in the world, causing a burden on global health and the economy. The enormously rising environmental changes, industrialization, and genetic modification have further exacerbated skin cancer statistics. Current treatment modalities such as surgery, radiotherapy, conventional chemotherapy, targeted therapy, and immunotherapy are facing several issues related to cost, toxicity, and bioavailability thereby leading to declined anti-skin cancer therapeutic efficacy and poor patient compliance. In the context of overcoming this limitation, several nanotechnological advancements have been witnessed so far. Among various nanomaterials, nanoparticles have endowed exorbitant advantages by acting as both therapeutic agents and drug carriers for the remarkable treatment of skin cancer. The small size and large surface area to volume ratio of nanoparticles escalate the skin tumor uptake through their leaky vasculature resulting in enhanced therapeutic efficacy. In this context, the present review provides up to date information about different types and pathology of skin cancer, followed by their current treatment modalities and associated drawbacks. Furthermore, it meticulously discusses the role of numerous inorganic, polymer, and lipid-based nanoparticles in skin cancer therapy with subsequent descriptions of their patents and clinical trials.

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.

Photothermally responsive theranostic nanocomposites for near-infrared light triggered drug release and enhanced synergism of photothermo-chemotherapy for gastric cancer

Near-infrared (NIR) photothermal therapy plays a critical role in the cancer treatment and diagnosis as a promising carcinoma treatment modalities nowadays. However, development of clinical application has been greatly limited due to the inefficient drug release and low tumor accumulation. Herein, we designed a NIR-light triggered indocyanine green (ICG)-based PCL core/P(MEO2MA-b-HMAM) shell nanocomposites (PPH@ICG) and evaluated their therapeutic effects in vitro and in vivo. The anticancer drug 5-fluorouracil (5Fu) and the photothermal agent ICG were loaded into a thermo-sensitive micelle (PPH@5Fu@ICG) by self-assembly. The nanoparticles formed were characterized using transmission electron microscopy, dynamic light scattering, and fluorescence spectra. The thermo-sensitive copolymer (PPH@5Fu@ICG) showed a great temperature-controlled drug release response with lower critical solution temperature. In vitro cellular uptake and TEM imaging proved that PPH@5Fu@ICG nanoparticles can home into the lysosomal compartments under NIR. Moreover, in gastric tumor-bearing nude mice, PPH@5Fu@ICG + NIR group exhibited excellent improvement in antitumor efficacy based on the NIR-triggered thermo-chemotherapy synergy, both in vitro and in vivo. In summary, the proposed strategy of synergistic photo-hyperthermia chemotherapy effectively reduced the 5Fu dose, toxic or side effect, which could serve as a secure and efficient approach for cancer theranostics.

A spark to the powder keg: Microneedle-based antitumor nanomedicine targeting reactive oxygen species accumulation for chemodynamic/photothermal/chemotherapy

HYPOTHESIS

Chemodynamic therapy (CDT) can efficiently kill cancer cells by producing hydroxyl radical (•OH), a kind of high-toxic reactive oxygen species (ROS), via Fenton or Fenton-like reactions. This study involved a versatile nanomedicine, MSN@DOX/GA-Fe/PDA (M@DGP), delivered via microneedles, which was expected to combine chemodynamic/photothermal/chemotherapy and efficiently increase ROS accumulation to achieve significant therapeutic efficacy against melanoma.

EXPERIMENTS

The composition of the synthesized nanoparticles was confirmed by a series of characterizations including transmission electron microscopy, Fourier transform infrared spectroscopy, and zeta potential. The photothermal properties of the nanomedicine was evaluated via infrared imaging, and •OH-producing ability was evaluated by UV-Vis and electron spin resonance. The mechanisms of ROS accumulation were studied in B16 cells by detecting intracellular •OH, glutathione, and ROS levels. The drug-loaded microneedles (M@DGP-MNs) were prepared, and their morphology and mechanical strength were characterized. The in vivo antimelanoma effect and biosafety evaluation of the nanomedicine were investigated in tumor-bearing C57 mice.

FINDINGS

M@DGP was successfully prepared and could achieve ROS accumulation through a photothermal-enhanced Fenton reaction, polydopamine-induced glutathione consumption, and doxorubicin-mediated mitochondrial dysfunction which induced oxidative stress and apoptosis of tumor cells. M@DGP-MNs showed superior antitumor efficacy and good biosafety, providing a promising strategy for melanoma treatment.

NCAPG2 contributes to the progression of malignant melanoma through regulating proliferation and metastasis

Malignant melanoma is a highly aggressive cutaneous neoplasm with increasing incidence worldwide. Non-SMC condensin II complex subunit G2 (NCAPG2) exerts import biological function in the pathogenesis of several tumors. In this study, the functional roles of NCAPG2 knockdown in malignant melanoma were revealed in in vitro and in vivo experiments. In vitro study demonstrated that NCAPG2 depletion could inhibit proliferation and migration and promote apoptosis of malignant melanoma cells. Our in vivo date further confirmed that NCAPG2 knockdown attenuated tumor growth of malignant melanoma. Interestingly, NCAPG2 drove tumor development of malignant melanoma through activating the signal transducer and activator of transcription 3 (STAT3). In conclusion, this study elaborated the tumor-promoting effects of NCAPG2 on malignant melanoma, and NCAPG2 may be a potential therapeutic target for malignant melanoma therapy.

Microneedles-mediated drug delivery system for the diagnosis and treatment of melanoma

As an emerging novel drug delivery system, microneedles (MNs) have a wide range of applications in the medical field. They can overcome the physiological barriers of the skin, penetrate the outermost skin of the human body, and form hundreds of reversible microchannels to enhance the penetration of drugs and deliver drugs to the diseased sites. So they have great applications in the diagnosis and treatment of melanoma. Melanoma is a kind of malignant tumor, the survival rate of patients with metastases is extremely low. The traditional methods of surgery and drug treatment for melanoma are often accompanied by large adverse reactions in the whole body, and the drug concentration is low. The use of MNs for transdermal administration can increase the drug concentration, reduce adverse reactions in the treatment process, and have good therapeutic effect on melanoma. This paper introduced various types of MNs and their preparation methods, summarized the diagnosis and various treatment options for melanoma with MNs, focused on the treatment of melanoma with dissolved MNs, and made prospect of MNs-mediated transdermal drug delivery in the treatment of melanoma.

How to Treat Melanoma? The Current Status of Innovative Nanotechnological Strategies and the Role of Minimally Invasive Approaches like PTT and PDT

Melanoma is the most aggressive type of skin cancer, the incidence and mortality of which are increasing worldwide. Its extensive degree of heterogeneity has limited its response to existing therapies. For many years the therapeutic strategies were limited to surgery, radiotherapy, and chemotherapy. Fortunately, advances in knowledge have allowed the development of new therapeutic strategies. Despite the undoubted progress, alternative therapies are still under research. In this context, nanotechnology is also positioned as a strong and promising tool to develop nanosystems that act as drug carriers and/or light absorbents to potentially improve photothermal and photodynamic therapies outcomes. This review describes the latest advances in nanotechnology field in the treatment of melanoma from 2011 to 2022. The challenges in the translation of nanotechnology-based therapies to clinical applications are also discussed. To sum up, great progress has been made in the field of nanotechnology-based therapies, and our understanding in this field has greatly improved. Although few therapies based on nanoparticulate systems have advanced to clinical trials, it is expected that a large number will come into clinical use in the near future. With its high sensitivity, specificity, and multiplexed measurement capacity, it provides great opportunities to improve melanoma treatment, which will ultimately lead to enhanced patient survival rates.

Research progress of microneedles in the treatment of melanoma

Melanoma is an aggressive malignancy deriving from melanocytes, which is characterized by high tendency of metastases and mortality rate. Current therapies for melanoma, like chemotherapy, immunotherapy and targeted therapy, have the problem of systemic exposure of drugs, which will lead to many side effects and premature degradation of drugs. The resulting low drug accumulation at the lesion limits the therapeutic effect on melanoma and makes the cure rate low. As an emerging drug delivery system, microneedles (MNs) can efficiently deliver drugs through the skin, increase the drug distribution in deeper tumor sites and minimize the leakage of therapeutic drugs into adjacent tissues, thus improving the therapeutic effect. In addition, compared with traditional drug delivery methods, MN-based drug delivery system has the advantages of simplicity, safety and little pain. So MNs can be developed for the treatment of melanoma, which can relieve the pain of patients and improve the survival rate. This review aims to introduce an update on the progress of MNs as an innovative strategy for melanoma, especially when MNs combining with different therapies against melanoma, such as chemotherapy, targeted therapy, immunotherapy, photothermal therapy (PTT), photodynamic therapy (PDT) and synergic therapy.

Recent advances in polymer microneedles for drug transdermal delivery: Design strategies and applications

In recent years, the transdermal drug delivery based on microneedles (MNs) technology has received extensive attention, which offers a safer and painless alternative to hypodermic needle injection. They can pierce the stratum corneum and deliver drugs to the epidermis and dermis-structures of skin, showing prominent properties such as minimally invasive, bypassing first-pass metabolism, and self-administered. A range of materials have been used to fabricate MNs, such as silicon, metal, glass, and polymers. Among them, polymer MNs have gained increasing attention from pharmaceutical and cosmetic companies as one of the promising drug delivery methods. Microneedle products have recently become available on the market, and some of them are under evaluation for efficacy and safety. This paper focuses on current state of polymer MNs in the drug transdermal delivery. The materials and methods for the fabrication of polymer MNs and their drug administration are described. The recent progresses of polymer MNs for treatment of cancer, vaccine delivery, blood glucose regulation, androgenetic alopecia, obesity, tissue healing, myocardial infarction and gout are reviewed. The challenges of MNs technology are summarized and the future development trend of MNs is also prospected. This article is protected by copyright. All rights reserved.

Bioimaging of Dissolvable Microneedle Arrays: Challenges and Opportunities

The emergence of microneedle arrays (MNAs) as a novel, simple, and minimally invasive administration approach largely addresses the challenges of traditional drug delivery. In particular, the dissolvable MNAs act as a promising, multifarious, and well-controlled platform for micro-nanotransport in medical research and cosmetic formulation applications. The effective delivery mostly depends on the behavior of the MNAs penetrated into the body, and accurate assessment is urgently needed. Advanced imaging technologies offer high sensitivity and resolution visualization of cross-scale, multidimensional, and multiparameter information, which can be used as an important aid for the evaluation and development of new MNAs. The combination of MNA technology and imaging can generate considerable new knowledge in a cost-effective manner with regards to the pharmacokinetics and bioavailability of active substances for the treatment of various diseases. In addition, noninvasive imaging techniques allow rapid, receptive assessment of transdermal penetration and drug deposition in various tissues, which could greatly facilitate the translation of experimental MNAs into clinical application. Relying on the recent promising development of bioimaging, this review is aimed at summarizing the current status, challenges, and future perspective on in vivo assessment of MNA drug delivery by various imaging technologies.

Intelligent and spatiotemporal drug release based on multifunctional nanoparticle-integrated dissolving microneedle system for synergetic chemo-photothermal therapy to eradicate melanoma

Cutaneous melanoma is one of the most common malignant skin cancer with high lethality. Chemotherapy and photothermal therapy are important and extensively studied treatment modalities for melanoma. However, these therapies still face some challenges, which severely restrict their further applications, such as unsatisfactory efficacy of monotherapy, nonspecific uptake and release during drug delivery, and unexpected adverse effects from system administration. Recently, the strategies of collaboration, functional modification, stimuli-responsive design, and topical administration all show great prospect for solving above problems. In this research, a multifunctional nanoparticle-integrated dissolving microneedle drug delivery system was constructed, in which the nanoparticles were prepared based on the framework with the incorporation of photothermal agent (CuS) into Zeolitic imidazolate framework-8 and functionalized by hyaluronic acid. This system can co-load multi-modal drugs, improve specific uptake and distribution of targeted tumor, deliver drug locally, and release drug intelligently and spatiotemporally, thereby promising a low-dose administration with high efficiency. The high inhibiting tumor performance and excellent systematic safety were verified both in vitro and in vivo. Together, this smart design overcame the drawbacks of monotherapy and conventional system administration. We believe the nanoparticle-integrated dissolving microneedles will be in prospect of clinical application for more superficial tumors with further delicate optimization. STATEMENT OF SIGNIFICANCE: Melanoma is one of the most common skin cancers with high lethality. Extensively studied chemotherapy and photothermal therapy still face some challenges, such as the limited therapeutic efficacy and the severe system adverse effects. In order to overcome these drawbacks, the multifunctional nanoparticle-integrated dissolving microneedles (DMNs) were designed. Especially, the nanoparticles could co-load multi-modal drugs, improve specific uptake, and release drug intelligently and spatiotemporally. The microneedles could increase the drug accumulation in tumor, thus achieving excellent therapeutic efficacy and reducing side effects. This system paved the way to a less invasive, more focused and efficient therapeutic strategy for melanoma therapy.

NK Cells in the Tumor Microenvironment as New Potential Players Mediating Chemotherapy Effects in Metastatic Melanoma

Until the last decade, chemotherapy was the standard treatment for metastatic cutaneous melanoma, even with poor results. The introduction of immune checkpoints inhibitors (ICIs) radically changed the outcome, increasing 5-year survival from 5% to 60%. However, there is still a large portion of unresponsive patients that would need further therapies. NK cells are skin-resident innate cytotoxic lymphocytes that recognize and kill virus-infected as well as cancer cells thanks to a balance between inhibitory and activating signals delivered by surface molecules expressed by the target. Since NK cells are equipped with cytotoxic machinery but lack of antigen restriction and needing to be primed, they are nowadays gaining attention as an alternative to T cells to be exploited in immunotherapy. However, their usage suffers of the same limitations reported for T cells, that is the loss of immunogenicity by target cells and the difficulty to penetrate and be activated in the suppressive tumor microenvironment (TME). Several evidence showed that chemotherapy used in metastatic melanoma therapy possess immunomodulatory properties that may restore NK cells functions within TME. Here, we will discuss the capability of such chemotherapeutics to: i) up-regulate melanoma cells susceptibility to NK cell-mediated killing, ii) promote NK cells infiltration within TME, iii) target other immune cell subsets that affect NK cells activities. Alongside traditional systemic melanoma chemotherapy, a new pharmacological strategy based on nanocarriers loaded with chemotherapeutics is developing. The use of nanotechnologies represents a very promising approach to improve drug tolerability and effectiveness thanks to the targeted delivery of the therapeutic molecules. Here, we will also discuss the recent developments in using nanocarriers to deliver anti-cancer drugs within the melanoma microenvironment in order to improve chemotherapeutics effects. Overall, we highlight the possibility to use standard chemotherapeutics, possibly delivered by nanosystems, to enhance NK cells anti-tumor cytotoxicity. Combined with immunotherapies targeting NK cells, this may represent a valuable alternative approach to treat those patients that do not respond to current ICIs.

Microneedle arrays integrated with living organisms for smart biomedical applications

Various living organisms have proven to influence human health significantly, either in a commensal or pathogenic manner. Harnessing the creatures may remarkably improve human healthcare and cure the intractable illness that is challenged using traditional drugs or surgical approaches. However, issues including limited biocompatibility, poor biosafety, inconvenience for personal handling, and low patient compliance greatly hinder the biomedical and clinical applications of living organisms when adopting them for disease treatment. Microneedle arrays (MNAs), emerging as a promising candidate of biomedical devices with the functional diversity and minimal invasion, have exhibited great potential in the treatment of a broad spectrum of diseases, which is expected to improve organism-based therapies. In this review, we systemically summarize the technologies employed for the integration of MNAs with specific living organisms including diverse viruses, bacteria, mammal cells and so on. Moreover, their applications such as vaccination, anti-infection, tumor therapy and tissue repairing are well illustrated. Challenges faced by current strategies, and the perspectives of integrating more living organisms, adopting smarter materials, and developing more advanced technologies in MNAs for future personalized and point-of-care medicine, are also discussed. It is believed that the combination of living organisms with functional MNAs would hold great promise in the near future due to the advantages of both biological and artificial species.

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

The excessive colonization of Propionibacterium acnes (P. acnes) is responsible for the genesis of acne vulgaris, a common inflammatory disease of skin. However, the conventional anti-acne therapies are always limited by various side effects, drug resistance, and poor skin permeability. Microneedles (MNs) are emerging topical drug delivery systems capable of noninvasively breaking through the skin stratum corneum barrier to efficiently enhance the transdermal drug penetration. Herein, MNs loaded with intelligent pH-sensitive nanoplatforms were constructed for amplified chemo-photodynamic therapy against acne vulgaris, jointly exerting antimicrobial and anti-inflammatory effects. The photosensitizer indocyanine green (ICG) was loaded into the zeolitic imidazolate framework-8 (ZIF-8) to improve its photostability, which would be triggered by 808 nm laser irradiation to generate cytotoxic reactive oxygen species (ROS) to result in oxidative damage and disturbed metabolic activities of P. acnes. In addition to the efficient drug delivery, the ZIF-8 carrier could selectively degrade in response to the acidic microenvironment of acne lesions, and the released Zn2+ also exhibited a potent antimicrobial activity. The fabricated ZIF-8-ICG@MNs presented an outstanding synergistic anti-acne efficiency both in vitro and in vivo. This bioresponsive microneedle patch is expected to be readily adapted as a generalized, modular strategy for noninvasive therapeutics delivery against superficial skin diseases.

Microneedle-mediated delivery of MIL-100(Fe) as a tumor microenvironment-responsive biodegradable nanoplatform for O2-evolving chemophototherapy

The low oxygen level in tumors significantly reduces the antitumor efficacy of photodynamic therapy (PDT). The provision of O₂ and monomeric hydrophobic photosensitizers (PSs) under physiological conditions would greatly help to shrink malignant tumors. We take advantage of the high porosity and multifunctionality of metal-organic frameworks (MOFs) to fabricate a simple all-in-one nanoplatform mediated by microneedle delivery to achieve synergistic O₂ evolution and chemophototherapy. An iron(III)-based MOF (MIL-100(Fe)) acted not only as a vehicle for the concurrent delivery of zinc phthalocyanine (ZnPc) and doxorubicin hydrochloride (Dox), but also to supply O₂ by decomposing hydrogen peroxide (H₂O₂) in the tumor microenvironment via a Fenton-like reaction. In vitro and in vivo experiments indicated that the nanoplatform had excellent biocompatibility and exerted enhanced anticancer effects. The encapsulated drug was sustainably released from the nanoplatform skeleton in response to acidic tumor microenvironments. Moreover, upon 660 nm light irradiation, ZnPc effectively produced reactive oxygen species (ROS) due to the reduction of hypoxia by MIL-100(Fe). A microneedle technique was adopted to directly deliver the nanoplatform into superficial tumors rather than via systemic circulation. Hence, this study provides a new strategy for more efficient chemophototherapy of hypoxic superficial tumors.

Dissolving Microneedles Developed in Association with Nanosystems: A Scoping Review on the Quality Parameters of These Emerging Systems for Drug or Protein Transdermal Delivery

The largest organ of the body provides the main challenge for the transdermal delivery of lipophilic or high molecular weight drugs. To cross the main barrier of the skin, the stratum corneum, many techniques have been developed and improved. In the last 20 years, the association of microneedles with nanostructured systems has gained prominence for its versatility and for enabling targeted drug delivery. Currently, the combination of these mechanisms is pointed to as an emerging technology; however, some gaps need to be answered to transcend the development of these devices from the laboratory scale to the pharmaceutical market. It is known that the lack of regulatory guidelines for quality control is a hindrance to market conquest. In this context, this study undertakes a scoping review of original papers concerning methods applied to evaluate both the quality and drug/protein delivery of dissolving and hydrogel-forming microneedles developed in association with nanostructured systems.