Responsive Microneedles as a New Platform for Precision Immunotherapy

Soluble-microneedle enhance three T-cell activation signals as efficient tumor vaccines for melanoma prevention and treatment

Therapeutic tumor vaccines, which activate self-T cells to eliminate tumors, hold tremendous promise in future cancer immunotherapy with high specificity and low side effects. To effectively activate T cell, dendritic cells (DCs) need simultaneously provide three indispensable signals to naive T cells, including MHC-antigen signal, costimulation signal and cytokine stimulation. However, current marketed therapeutic tumor vaccines still suffer from lacking the ability to activate three stimulation signals at the same time, which resulted to the low response rate and unsatisfied therapeutic efficiency. Here, we proposed a soluble microneedle-based tumor vaccines (TR-12@LGMN) which facilitate triple activation of antigen presentation and induce high immune response rate. First, the melanoma-specific antigen tyrosinaserelated protein-2 (Trp2), Resiquimod (R848), and IL-12 mRNA co-loaded liposomes (TR-12@LIPO) was prepared. The TR-12@LIPO ensured triple-activating three essential signals of antigen presentation through enhancing the binding of MHC I-antigen peptides to T cell receptor (TCR), the binding of CD80/86 on DCs to CD28 on T cells, and the release of cytokines for T cells activation. Second, TR-12@LIPO was co-dispersed in polyvinylpyrrolidone-polyvinyl alcohol (PVP-PVA) matrix with granulocyte-macrophage colony stimulating factor (GM-CSF) to prepare TR-12@LGMN by mold method. The TR-12@LGMN was quadrilateral shape with sufficient mechanical strength for skin piercing. After skin insertion, TR-12@LGMN dissolved in the skin interstitial fluid to release GM-CSF and TR-12@LIPO. DCs were recruited by GM-CSF and uptaked TR-12@LIPO. TR-12@LIPO showed enhancement of cross-presentation by antigen cytoplasmic delivery, DCs maturation and IL-12 secretion. In vivo results showed that TR-12@LGMN could efficiently activate CD8+ T cells, induce antigen-specific cytotoxic T cells (CTLs) and memory T cell (Tm). Ultimately, strong anti-tumor immunity and long-term durable tumor control were achieved in the B16F10 tumor prevention and treatment model. Overall, our work proposes a triple-activated antigen presentation strategy and designs a microneedle-based tumor vaccine for skin delivery, revealing a potential promising direction for the development of new therapeutic tumor vaccines methods.

Role of Microneedles for Improved Treatment of Obesity: Progress and Challenges

Obesity is a global metabolic health epidemic characterized by excessive lipid and fat accumulation, leading to severe conditions such as diabetes, cancer, and cardiovascular disease. Immediate attention and management of obesity-related health risks are most warranted. The imbalance between fat absorption, metabolic rate, and environmental and genetic factors is responsible for obesity. Treatment typically involves lifestyle modifications, pharmacotherapy, and surgery. While lifestyle changes are crucial, effective treatment often necessitates medication as a preferred adjunct strategy. However, medications commonly used, such as oral pharmacotherapy, often show side effects due to systemic exposure and, thus, may not effectively target the intended areas, leading to drug loss. On the other hand, transdermal administration of drugs with microneedle (MN)-based technologies, a painless drug delivery approach with patient compliance, is gaining interest as an alternative obesity treatment, as it directly targets adipose tissue via local delivery, minimizing system exposure and dose reduction. This Review addresses the pathophysiology of obesity, current treatment strategies, challenges in the treatment of obesity using conventional formulations, the importance of the use of nano-based medications through transdermal delivery, and the use of MNs as a promising platform for the effective delivery of nanoparticle-based anti-obesity medications. The potential of combining MNs with stimuli-responsive and non-responsive adjuvant therapies to enhance treatment efficacy and patient outcomes is explored. In addition, the limitations and future perspectives related to the use of MNs for obesity are addressed to highlight the transformative potential of this technology for obesity management. MNs hold promise in precisely delivering anti-obesity drugs while requiring lower dosages and minimizing side effects compared to conventional oral or injectable therapies and ultimately improving the quality of life for individuals struggling with obesity and its associated comorbidities.

Graphene-Based Polymeric Microneedles for Biomedical Applications: A Comprehensive Review

Transdermal drug delivery presents a promising noninvasive approach, bypassing first-pass metabolism and gastrointestinal degradation. However, the stratum corneum (SC) barrier limits drug absorption, necessitating the development of effective delivery systems. Microneedles, particularly polymer-based ones, offer a solution by penetrating the SC while avoiding critical nerves and capillaries. These microneedles are biodegradable, nontoxic, and easily manufacturable, making them a highly attractive platform for transdermal drug delivery. However, their clinical application remains limited due to suboptimal therapeutic efficacy and slow drug release rates. Recent advancements have introduced the incorporation of nanodrugs, such as nanoparticles and encapsulated drugs, into microneedles to enhance drug delivery efficiency. Among the materials explored, graphene and its derivatives, including graphene oxide (GO) and reduced graphene oxide (rGO), have garnered significant attention. Their exceptional mechanical strength, electrical conductivity, and antibacterial properties not only improve the mechanical performance of microneedles but also enhance drug release rates and biocompatibility. This review synthesizes the current state of microneedle technologies, focusing on the materials, fabrication techniques, and performance challenges. It particularly examines the potential of graphene-based microneedles, comparing them to traditional polymer-based microneedles in terms of drug release efficiency and stability. The review highlights key challenges, such as scalability, biocompatibility, and fabrication complexity, and suggests future research directions to address these issues. The incorporation of graphene quantum dots (GQDs) is identified as a promising avenue for improving drug release profiles, stability, and real-time tracking of drug diffusion. Finally, the review outlines emerging applications, including smart drug delivery systems, biosensing, and real-time monitoring, urging further exploration to unlock the full potential of graphene-enhanced microneedles in clinical settings.

Recent progress of microneedles in transdermal immunotherapy: A review

Since human skin is an immune organ, a large number of immune cells are distributed in the epidermis and the dermis of the skin. Transdermal immunotherapy shows great therapeutic advantages in innate immunotherapy and adaptive immunotherapy. To solve the problem that macromolecules are difficult to penetrate into the skin, the microneedle technology can directly break through the skin barrier using micron-sized needles in a non-invasive and painless way for transdermal drug delivery. Therefore, it is considered to be an effective technology to increase drug transdermal absorption. In this review, the types of preparation, the combinations with different techniques and the mechanisms of microneedles in transdermal immunotherapy were summarized. Compared with traditional immunotherapy like intramuscular injection and subcutaneous injection, the microneedle has many advantages in transdermal immunotherapy, such as reducing patient pain, enhancing vaccine stability, and inducing stronger immune responses. Although there are still some limitations to be solved, the application of microneedle technology in transdermal immunotherapy is undoubtedly a promising means of drug delivery.

Biomaterial-Based Sustained-Release Drug Formulations for Localized Cancer Immunotherapy

Cancer immunotherapy has revolutionized clinical cancer treatments by taking advantage of the immune system to selectively and effectively target and kill cancer cells. However, clinical cancer immunotherapy treatments often have limited efficacy and/or present severe adverse effects associated primarily with their systemic administration. Localized immunotherapy has emerged to overcome these limitations by directly targeting accessible tumors via local administration, reducing potential systemic drug distribution that hampers drug efficacy and safety. Sustained-release formulations can prolong drug activity at target sites, which maximizes the benefits of localized immunotherapy to increase the therapeutic window using smaller dosages than those used for systemic injection, avoiding complications of frequent dosing. The performance of sustained-release formulations for localized cancer immunotherapy has been validated preclinically using various implantable and injectable scaffold platforms. This review introduces the sustained-release formulations developed for localized cancer immunotherapy and highlights their biomaterial-based platforms for representative classes, including inorganic scaffolds, natural hydrogels, synthetic hydrogels, and microneedle patches. The design rationale and other considerations are summarized for further development of biomaterials for the construction of optimal sustained-release formulations.

Novel Drug Delivery Systems: An Important Direction for Drug Innovation Research and Development

The escalating demand for enhanced therapeutic efficacy and reduced adverse effects in the pharmaceutical domain has catalyzed a new frontier of innovation and research in the field of pharmacy: novel drug delivery systems. These systems are designed to address the limitations of conventional drug administration, such as abbreviated half-life, inadequate targeting, low solubility, and bioavailability. As the disciplines of pharmacy, materials science, and biomedicine continue to advance and converge, the development of efficient and safe drug delivery systems, including biopharmaceutical formulations, has garnered significant attention both domestically and internationally. This article presents an overview of the latest advancements in drug delivery systems, categorized into four primary areas: carrier-based and coupling-based targeted drug delivery systems, intelligent drug delivery systems, and drug delivery devices, based on their main objectives and methodologies. Additionally, it critically analyzes the technological bottlenecks, current research challenges, and future trends in the application of novel drug delivery systems.

Hydrogel Microneedles with Programmed Mesophase Transitions for Controlled Drug Delivery

Microneedle-based drug delivery offers an attractive and minimally invasive administration route to deliver therapeutic agents through the skin by bypassing the stratum corneum, the main skin barrier. Recently, hydrogel-based microneedles have gained prominence for their exceptional ability to precisely control the release of their drug cargo. In this study, we investigated the feasibility of fabricating microneedles from triblock amphiphiles with linear poly(ethylene glycol) (PEG) as the hydrophilic middle block and two dendritic side-blocks with enzyme-cleavable hydrophobic end-groups. Due to the poor formation and brittleness of microneedles made from the neat amphiphile, we added a sodium alginate base layer and tested different polymeric excipients to enhance the mechanical strength of the microneedles. Following optimization, microneedles based on triblock amphiphiles were successfully fabricated and exhibited favorable insertion efficiency and low height reduction percentage when tested in Parafilm as a skin-simulant model. When tested against static forces ranging from 50 to 1000 g (4.9-98 mN/needle), the microneedles showed adequate mechanical strength with no fractures or broken segments. In buffer solution, the solid microneedles swelled into a hydrogel within about 30 s, followed by their rapid disintegration into small hydrogel particles. These hydrogel particles could undergo slow enzymatic degradation to soluble polymers. In vitro release study of dexamethasone (DEX), as a steroid model drug, showed first-order drug release, with 90% released within 6 days. Eventually, DEX-loaded MNs were subjected to an insertion test using chicken skin and showed full penetration. This study demonstrates the feasibility of programming hydrogel-forming microneedles to undergo several mesophase transitions and their potential application as a delivery system for self-administration, increased patient compliance, improved efficacy, and sustained drug release.

Advances in biomedical systems based on microneedles: design, fabrication, and application

Wearable devices have become prevalent in biomedical studies due to their convenient portability and potential utility in biomarker monitoring for healthcare. Accessing interstitial fluid (ISF) across the skin barrier, microneedle (MN) is a promising minimally invasive wearable technology for transdermal sensing and drug delivery. MN has the potential to overcome the limitations of conventional transdermal drug administration, making it another prospective mode of drug delivery after oral and injectable. Subsequently, combining MN with multiple sensing approaches has led to its extensive application to detect biomarkers in ISF. In this context, employing MN platforms and control schemes to merge diagnostic and therapeutic capabilities into theranostic systems will facilitate on-demand therapy and point-of-care diagnostics, paving the way for future MN technologies. A comprehensive analysis of the growing advances of microneedles in biomedical systems is presented in this review to summarize the latest studies for academics in the field and to offer for reference the issues that need to be addressed in MN application for healthcare. Covering an array of novel studies, we discuss the following main topics: classification of microneedles in the biomedical field, considerations of MN design, current applications of microneedles in diagnosis and therapy, and the regulatory landscape and prospects of microneedles for biomedical applications. This review sheds light on the significance of microneedle-based innovations, presenting an analysis of their potential implications and contributions to the community of wearable healthcare technologies. The review provides a comprehensive understanding of the field's current state and potential, making it a valuable resource for academics and clinicians seeking to harness the full potential of MN applications.

Recent advances in melittin-based nanoparticles for antitumor treatment: from mechanisms to targeted delivery strategies

As a naturally occurring cytolytic peptide, melittin (MLT) not only exhibits a potent direct tumor cell-killing effect but also possesses various immunomodulatory functions. MLT shows minimal chances for developing resistance and has been recognized as a promising broad-spectrum antitumor drug because of this unique dual mechanism of action. However, MLT still displays obvious toxic side effects during treatment, such as nonspecific cytolytic activity, hemolytic toxicity, coagulation disorders, and allergic reactions, seriously hampering its broad clinical applications. With thorough research on antitumor mechanisms and the rapid development of nanotechnology, significant effort has been devoted to shielding against toxicity and achieving tumor-directed drug delivery to improve the therapeutic efficacy of MLT. Herein, we mainly summarize the potential antitumor mechanisms of MLT and recent progress in the targeted delivery strategies for tumor therapy, such as passive targeting, active targeting and stimulus-responsive targeting. Additionally, we also highlight the prospects and challenges of realizing the full potential of MLT in the field of tumor therapy. By exploring the antitumor molecular mechanisms and delivery strategies of MLT, this comprehensive review may inspire new ideas for tumor multimechanism synergistic therapy.

Smart Responsive Microneedles for Controlled Drug Delivery

As an emerging technology, microneedles offer advantages such as painless administration, good biocompatibility, and ease of self-administration, so as to effectively treat various diseases, such as diabetes, wound repair, tumor treatment and so on. How to regulate the release behavior of loaded drugs in polymer microneedles is the core element of transdermal drug delivery. As an emerging on-demand drug-delivery technology, intelligent responsive microneedles can achieve local accurate release of drugs according to external stimuli or internal physiological environment changes. This review focuses on the research efforts in smart responsive polymer microneedles at home and abroad in recent years. It summarizes the response mechanisms based on various stimuli and their respective application scenarios. Utilizing innovative, responsive microneedle systems offers a convenient and precise targeted drug delivery method, holding significant research implications in transdermal drug administration. Safety and efficacy will remain the key areas of continuous efforts for research scholars in the future.

Polysaccharide-based tumor microenvironment-responsive drug delivery systems for cancer therapy

The biochemical indicators of tumor microenvironment (TME) that are different from normal tissues provide the possibility for constructing intelligent drug delivery systems (DDSs). Polysaccharides with good biocompatibility, biodegradability, and unique biological properties are ideal materials for constructing DDSs. Nanogels, micelles, organic-inorganic nanocomposites, hydrogels, and microneedles (MNs) are common polysaccharide-based DDSs. Polysaccharide-based DDSs enable precise control of drug delivery and release processes by incorporating TME-specific biochemical indicators. The classification and design strategies of polysaccharide-based TME-responsive DDSs are comprehensively reviewed. The advantages and challenges of current polysaccharide-based DDSs are summarized and the future directions of development are foreseen. The polysaccharide-based TME-responsive DDSs are expected to provide new strategies and solutions for cancer therapy and make important contributions to the realization of precision medicine.