Strategies to develop polymeric microneedles for controlled drug release

Mechanistic study of cancer drug delivery: Current techniques, limitations, and future prospects

Cancer drug delivery remains a critical challenge with systemic toxicity, poor drug bioavailability, and a lack of effective targeting. Overcoming these barriers is essential for improving treatment efficacy and patient outcomes. This review discusses current drug delivery techniques that reshape cancer therapy by offering precise, controlled-release tailored to tumor-specific features. Innovations in nanotechnology, immunotherapy, and gene therapy enable interventions at molecular and cellular levels. Radiomics and pathomics integrate high-dimensional data to optimize diagnostics and treatment planning. Combination therapy addresses the complexities of tumor heterogeneity by synergizing multiple agents within a single therapeutic framework, while peptide-drug conjugates enhance specificity and potency. Hydrogel-based systems and microneedle arrays offer localized, sustained release, significantly improving therapeutic outcomes. However, clinical translation of these advancements faces significant barriers such as drug resistance, off-target effects, scalability, cost, and ethical concerns. Moreover, regulatory complexities and the economic feasibility of these therapies highlight the need for innovative frameworks to make them accessible globally. Therefore, there is a need for innovation in gene and cell therapy, next-generation drug delivery platforms, and personalized medicine. This review focuses on recent advancements in drug delivery techniques over the past decade, evaluating their limitations and exploring potential future directions for transforming cancer treatment.

Transdermal delivery of timolol maleate using hydrogel microneedles for the treatment of infantile haemangiomas

Infantile haemangioma (IH), the most prevalent vascular tumour in infants, requires early intervention because of the potential complications in critical areas such as the head and face. Current treatments, including topical timolol maleate (TIM), face challenges such as poor compliance, low drug utilisation, and lengthy treatment durations. In this study, we developed a hydrogel microneedle (MN) using photocurable bovine serum albumin methacryloyl (BSAMA) as a carrier for TIM. Our results showed the controlled release of TIM from BSAMA-TIM MNs, with approximately 69 % release ratio within 72 h. In-vivo studies on nude mice demonstrated that BSAMA-TIM-MNs inhibited the growth of haemangioma xenografts. Our TIM-delivering MNs exhibited high therapeutic efficacy, minimal cytotoxicity, and reduced dosing frequency. In conclusion, BSAMA-TIM MNs provide a promising strategy for treating IH.

Computational hybrid analysis of drug diffusion in three-dimensional domain with the aid of mass transfer and machine learning techniques

Molecular diffusion of drugs is of major importance for development and understanding drug delivery systems. Indeed, the main phenomenon which is controlling the rate of release is molecular diffusion which can be controlled via different phenomena such as interactions with the drug carrier and solution. In this work, we developed a novel hybrid model based on mass transfer and machine learning for predicting drug diffusion in a 3D space. The mass transfer equation including diffusion is solved in the domain and then the data is extracted for building machine learning models. The present study presents the findings of an analysis conducted with the objective of constructing precise regression models for the prediction of chemical species concentration (C) for a drug diffusion through a three-dimensional space, utilizing coordinates (x, y, z). The dataset comprises over 22,000 data points, with each point containing the coordinates ([Formula: see text]) and the corresponding concentration (C) in mol/m³. We employ three tree-based ensemble models: Kernel Ridge Regression (KRR), [Formula: see text]-Support Vector Regression ([Formula: see text]-SVR), and Multi Linear Regression (MLR) for modeling the relationship between spatial coordinates and the concentration. Hyperparameter optimization is performed using the Bacterial Foraging Optimization Algorithm (BFO) to fine-tune the models. The results reveal that [Formula: see text]-SVR has the highest performance with a score of 0.99777 in terms of R2, followed by KRR with an R2 score of 0.94296, and MLR with an R2 value of 0.71692. Additionally, [Formula: see text]-SVR exhibits the lowest RMSE and MAE, showing excellent predictive accuracy compared to KRR and MLR. Overall, our analysis demonstrates the effectiveness of employing tree-based ensemble models coupled with BFO for accurately predicting chemical concentrations in three-dimensional space, with [Formula: see text]-SVR emerging as the most promising model for this task. These findings have implications for various applications such as environmental monitoring, pollutant dispersion modeling, and chemical process optimization.

Whispers beneath the skin: how microneedles are shaping tomorrow's therapies

Microneedles (MNs) offer a minimally invasive alternative to conventional patch-based and injection-based drug delivery methods. By bypassing first-pass metabolism and enhancing skin permeability, MNs significantly improve drug bioavailability. Their applications span vaccine administration, chronic disease management, and cosmetic treatments. Five major types of MNs have been identified, each with distinct mechanisms of action. Recent research focuses on advanced manufacturing techniques, stimuli-responsive materials, and combination drug therapies. Common materials include silicon, hydrogels, and biodegradable polymers, with growing interest in sustainable alternatives. Despite their potential, MNs face challenges related to drug stability, cost-effective production, and regulatory approvals. Emerging technologies, such as The integration of 3D printing, artificial intelligence, and biosensing technologies is driving significant advancements in personalized medicine. Clinical trials involving vaccines, biologics, and gene therapies are accelerating their path toward regulatory acceptance. MNs support patient self-administration, reduce dependency on healthcare infrastructure, and expand global access to treatment. Their integration with telemedicine and remote drug monitoring positions them as a transformative tool in future medical practice.

Advances in microneedle-based drug delivery system for metabolic diseases: structural considerations, design strategies, and future perspectives

As the prevalence of metabolic diseases such as diabetes and obesity continue to rise, the search for more effective and convenient treatments has become a crucial issue in medical research. Microneedles (MNs), as an innovative drug delivery system, have shown advantages in the treatment of metabolic diseases in recent years. MNs-based drug delivery system, which use MNs to deliver drugs directly to the subcutaneous tissue, improve drug bioavailability and reduce systemic side effects. This review aims to summarize the latest concepts, designs, and types of MNs, and to investigate the materials and manufacturing methods used in their construction. Subsequently, the mechanisms of drug delivery and graded release of MNs and recent research progress are further summarized. This article focuses on the application of MNs in the treatment of common metabolic diseases, with a special emphasis on the progress and optimization of diabetic and anti-obesity MNs. The main challenges and future perspectives in the production and evaluation of MNs, as well as in enhancing treatment efficacy and improving safety, are elucidated.

Microneedle drug delivery carriers capable of achieving sustained and controlled release function

Traditional injection methods such as subcutaneous (SC) and intramuscular (IM) injections are commonly used in clinical settings for their rapid therapeutic effects. However, these methods can cause additional pain to patients and may lead to infections and nerve damage. Oral administration and other forms of drug delivery are susceptible to the first-pass effect, resulting in low bioavailability and systemic side effects. In recent years, with the advancement of material and computer sciences, a novel drug delivery method known as microneedles has emerged. Microneedle drug delivery systems combine the efficiency of traditional injections with the safety of transdermal absorption, representing a new type of transdermal drug delivery systems (TDDs) formulation. Among these, microneedles with sustained and controlled release characteristics have garnered significant attention from researchers, as they facilitate optimal therapeutic effects, reduce the frequency of drug administration, enhance patient compliance, and minimize the toxic side effects of drugs. The application sites for microneedles are diverse and not limited to skin tissue. The controlled release characteristics of drugs can be easily manipulated. For instance, in hydrogel microneedles, this can be achieved by increasing the cross-linking degree of the hydrogel or by chemically modifying the polymers. This article provides a detailed description of the drug release mechanisms of sustained and controlled release microneedles, the impact of different materials on their release properties, recent research progress and application fields of sustained and controlled release microneedles, as well as their future prospects and challenges.

Microneedle-aided nanotherapeutics delivery and nanosensor intervention in advanced tissue regeneration

Microneedles (MNs) have been extensively used as transdermal therapeutics delivery devices since 1998 due to their capacity to penetrate physiological barriers with minimal invasiveness. Recent advances demonstrate the potential of MNs in improving diverse tissue regeneration when integrated with nanometer-sized therapeutics or sensors. This synergistic strategy can enhance drug delivery efficiency and therapeutic outcomes, and enable precise and personalized therapies through real-time monitoring of the repair process. In this review, we discuss how optimized MNs (through adjustments in geometry, material properties, and modular structure), when combined with dimension- and composition-specific nanomaterials, enhance tissue regeneration efficiency. Moreover, integrating stimuli-responsive nanotherapeutics or nanosensors into MNs for spatiotemporal-controlled and targeted drug release, physiotherapy effects, and intelligent monitoring is systematically outlined. Furthermore, we summarize therapeutic applications of nanotherapeutics-MN platforms in various soft and hard tissues, including skin, hair follicles (HF), cornea, joint, tendons, sciatic nerves, spinal cord, periodontium, oral mucosa, myocardium, endometrium, bone and intervertebral discs (IVD). Notably, recent attempts using nanosensor-MN platforms as smart wearable devices for monitoring damaged tissues via interstitial fluid (ISF) extraction and biomarker sensing are analyzed. This review potentially provides tissue regeneration practitioners/researchers with a cross-disciplinary perspective and inspiration.

Dissolving microneedle patch integrated with microparticle depots for sustained intradermal delivery of donepezil

Alzheimer's Disease (AD) is a significant global health challenge worldwide and imposes a substantial economic burden. Due to the shortcomings of conventional pharmaceutical formulations (e.g., tablet and microparticle depot injection), such as low bioavailability, frequent dosing, and the inconvenience related to injection), there is a pressing need to develop a convenient and effective medical cue for AD treatment. Here, a hybrid dissolving microneedle patch integrated with donepezil (DNP)-encapsulated biodegradable microparticle depots is introduced for sustained DNP delivery, reduced dosing frequency, and improved patient compliance. Once the microneedle patch delivers DNP-encapsulated microparticle depots into the skin, they subsequently act as drug reservoirs for the sustained release of the DNP for over 2 weeks. In vitro and ex vivo insertion experiments showed that the microneedle patches could provide enough mechanical strength and good morphology, as well as enhanced dissolvability and retention of microparticle depots in the skin. In vitro cytocompatibility study in NIH3T3 cells demonstrated the biocompatibility of the materials comprising microneedle patch. This hybrid system offers a promising alternative to conventional oral or injectable therapies for AD by enabling self-administrable, pain-free, and long-acting transdermal delivery.

A gelatin microneedles featuring antibacterial and reactive oxygen species scavenging properties for treating Vibrio vulnificus-infected wounds

Vibrio vulnificus (V. vulnificus) is highly toxic and lethal. Vibrio vulnificus infected wounds are one of the great challenges in the treatment of its associated diseases. Recent studies have found that dissolvable microneedles can effectively promote repair of infected wounds. Therefore, gelatin microneedles (CeO2-CIP MN) doped with cerium dioxide nanoparticles (CeO2 NPs) and ciprofloxacin (CIP) were rationally designed and prepared based on the characteristics of the microenvironment of bacterial infection. The results of in vitro studies showed that CeO2-CIP MN possessed broad-spectrum antimicrobial activity and antioxidant activity. Importantly, in the seawater-immersed V. vulnificus infected wound model, CeO2-CIP MN effectively killed V. vulnificus, scavenged wound reactive oxygen species (ROS), and promoted cell migration, which subsequently accelerated the repair of the infected wound. In conclusion, this study demonstrated that CeO2-CIP MN can effectively promote the repair of V. vulnificus infected wounds, and also provide ideas for innovative treatment modalities for marine-related diseases.

A comprehensive review and advanced biomolecule-based therapies for osteoporosis

BACKGROUND

The prevalence of osteoporosis (OP) on a global scale is significantly elevated that causes life threatening issues. The potential of groundbreaking biomolecular therapeutics in the field of OP is highly encouraging. The administration of biomolecular agents has the potential to mitigate the process of bone demineralization while concurrently augmenting the regenerative capacity of bone tissue, thereby facilitating a personalized therapeutic approach. Biomolecules-based therapies showed promising results in term of bone mass protection and restoration in OP.

AIM OF REVIEW

We summarized the recent biomolecular therapies with notable progress in clinical, demonstrating the potential to transform illness management. These treatments frequently utilize different biomolecule based strategies. Biomolecular therapeutics has a targeted character, which results in heightened specificity and less off-target effects, ultimately leading to increased patient outcomes. These aspects have the capacity to greatly enhance the management of OP, thus resulting in a major enhancement in the quality of life encountered by individuals affected by this condition.

Hydrogel tissue adhesive: Adhesion strategy and application

Hydrogel tissue adhesives have emerged as a promising alternative to conventional wound closure methods such as sutures and staples due to their operational simplicity demonstrated biocompatibility and capacity for multifunctional integration. However, complex and variable tissue microenvironments and dynamic adhesion surfaces still challenge the actual adhesion performance of adhesives, especially natural polymer-based adhesives. In addition, to expand the application of adhesives in biomedical fields, there is an urgent need to further improve tissue adhesion performance through composition design, adhesion mechanism research and bioeffect development. This review focuses on the adhesive properties of adhesives and their applications in biomedical fields. Adhesion-cohesion equilibria, forms of adhesion failure, methods for improving cohesion and various interfacial adhesion mechanisms are presented. Moreover, practical biomedical applications of tissue adhesives are reviewed, focusing on skin, heart, stomach, liver, and cornea. Finally, this review looks ahead to a new generation of multi-functional, strong adhesion tissue adhesives, in the hope of providing inspiration to those working in the field.

Polymeric microneedle advancements in macromolecule drug delivery: current trends, challenges, and future perspectives

Microneedles (MNs) offer a transformative solution for delivering macromolecules, including proteins, RNA, and peptides. These are critical in treating complex diseases but face significant challenges such as immunogenicity, poor stability, high molecular weight, and delivery efficiency. Unlike conventional methods, MNs efficiently bypass biological barriers like the stratum corneum, enabling precise and minimally invasive transdermal drug delivery. This review explores various MN types such as solid, coated, hollow, hydrogel-forming, and dissolving and their therapeutic applications in cancer immunotherapy, diabetes management, and osteoporosis treatment. For instance, dissolving MNs have been employed for transdermal insulin delivery, enhancing patient compliance and therapeutic outcomes. Similarly, hydrogel MNs have shown promise in sustained drug release for immunotherapy applications. By addressing cost and scalability issues, polymeric MNs demonstrate significant potential for clinical translation, paving the way for innovations in macromolecule delivery, diagnostics, and personalised medicine. This review underscores the pivotal role of MNs in redefining drug delivery systems, offering improved efficacy, patient comfort, and accessibility.

Smart core-shell microneedles for psoriasis therapy: In situ self-assembly of calcium ion-coordinated dexamethasone hydrogel

Psoriasis is a prevalent relapsing dermatological condition that often necessitates lifelong treatment. The distinctive thickening of the stratum corneum presents a challenge to drug penetration. The employment of microneedles has been demonstrated to enhance the transdermal drug delivery efficacy by creating multiple microchannels in the skin. Nevertheless, polymeric microneedles often encounter difficulties in meeting the requirements for sustained drug release. It is imperative to acknowledge that sustained-release hydrogel microneedles are invariably fabricated under harsh crosslinking conditions. In addressing these challenges, a core-shell microneedles (CSMNs) system was customized at a facile, accessible process, enabling the in situ formation of supramolecular microhydrogels within the skin. This concept was realized by leveraging the interaction between the therapeutic drug dexamethasone sodium phosphate (DexP) and calcium chloride (CaCl2), combined with the differential biphasic release technology (DexP HMNs). Upon insertion into the skin, the core of the microneedles rapidly released CaCl2, which diffused to the shell and formed a hydrogel with DexP, creating multiple reservoirs for the sustained release of DexP. In vitro transdermal permeation experiments demonstrated that DexP HMNs greatly prolonged the skin retention time of DexP. In the context of psoriasis treatment, DexP HMNs were demonstrated to be more effective than DexP CSMNs in inhibiting keratinocyte proliferation and significantly reducing the levels of inflammatory factors and immune cell infiltration at the lesion site. This study provides a new direction for the development of intelligent microneedle drug delivery systems for sustained drug release and enhanced management of chronic skin diseases.

Chlorhexidine-loaded microneedles for treatment of oral diseases

Chlorhexidine (CHX) is a gold standard therapeutic agent against clinical oral pathogens. However, its oral use is limited due to unpleasant taste, alteration in taste buds, staining of teeth and mucous membranes. Therefore, CHX-loaded PLGA microneedles (MNs) were fabricated for local and controlled release in the oral cavity, using a casting mold method. The MNs were well-formed with sharp MN tips and flat baseplates, showing quadrangular pyramidal shapes with average needle height and base width of about 500 and 200 µm, respectively. CHX was successfully incorporated into the PLGA-based MNs, exhibiting high encapsulation efficiency. CHX-PLGA MNs were further characterized in terms of ATR-FTIR and DSC, indicating intermolecular interactions between CHX and PLGA. In vitro CHX release exhibited an initial burst release within the first 24 h, accompanied by a slower release rate, reaching cumulative release of ca. 56 % after 10 days. The antibacterial effect of CHX-PLGA MNs on Streptococcus mutans (S. mutans) was evaluated using different techniques. In agar diffusion assay, the MNs displayed sustained antimicrobial activity over 8 days, while they significantly reduced the bacterial growth of S. mutans on the first 4 days in a planktonic experimental setup. No antibacterial effect was recorded for the blank PLGA MNs that served as a control group. Interestingly, CHX-PLGA MNs eliminated biofilm formation and metabolic activity for 3 days compared with biofilm formed in the presence of blank MNs. Then, a rebound effect was recorded. A weak antibiofilm effect and anti-metabolic activity was observed when MNs tested against pre-formed biofilm. Taken together, CHX-PLGA MNs hold promise as a viable delivery modality for localized and sustainedantimicrobial activity in the oral cavity. Further research is required to optimize the formulation and assess efficacy and safety in clinical settings.

Tailoring Design of Microneedles for Drug Delivery and Biosensing

Microneedles (MNs) are emerging as versatile tools for both therapeutic drug delivery and diagnostic monitoring. Unlike hypodermic needles, MNs achieve these applications with minimal or no pain and customizable designs, making them suitable for personalized medicine. Understanding the key design parameters and the challenges during contact with biofluids is crucial to optimizing their use across applications. This review summarizes the current fabrication techniques and design considerations tailored to meet the distinct requirements for drug delivery and biosensing applications. We further underscore the current state of theranostic MNs that integrate drug delivery and biosensing and propose future directions for advancing MNs toward clinical use.

Recent development of micro-nano carriers for oral antineoplastic drug delivery

Chemotherapy is widely recognized as a highly efficacious modality for cancer treatment, involving the administration of chemotherapeutic agents to target and eradicate tumor cells. Currently, oral administration stands as the prevailing and widely utilized method of delivering chemotherapy drugs. However, the majority of anti-tumor medications exhibit limited solubility and permeability, and poor stability in harsh gastrointestinal environments, thereby impeding their therapeutic efficacy for chemotherapy. Therefore, more and more micro-nano drug delivery carriers have been developed and used to effectively deliver anti-cancer drugs, which can overcome physiological barriers, facilitate oral administration, and ultimately improve drug efficacy. In this paper, we first discuss the effects of various biological barriers on micro-nano drug carriers and oral administration approach. Then, the development of micro-nano drug carriers based on various biomedical components, such as micelles, dendrimers, hydrogels, liposomes, inorganic nanoparticles, etc. were introduced. Finally, the current dilemma and the potential of oral drug delivery for clinical treatment were discussed. The primary objective of this review is to introduce various oral delivery methods and serve as a point of reference for the advancement of novel oral delivery carriers, with the ultimate goal of informing the development of future clinical applications.

Modelling Hollow Microneedle-Mediated Drug Delivery in Skin Considering Drug Binding

Background/Objectives: Microneedle(MN)-based drug delivery is one of the potential approaches to overcome the limitations of oral and hypodermic needle delivery. An in silico model has been developed for hollow microneedle (HMN)-based drug delivery in the skin and its subsequent absorption in the blood and tissue compartments in the presence of interstitial flow. The drug's reversible specific saturable binding to its receptors and the kinetics of reversible absorption across the blood and tissue compartments have been taken into account. Methods: The governing equations representing the flow of interstitial fluid, the transport of verapamil in the viable skin and the concentrations in the blood and tissue compartments are solved using combined Marker and Cell and Immersed Boundary Methods to gain a quantitative understanding of the model under consideration. Results: The viscoelastic skin is predicted to impede the transport of verapamil in the viable skin and, hence, reduce the concentrations of all forms in the blood and the tissue compartments. The findings reveal that a higher mean concentration in the viable skin is not always associated with a longer MN length. Simulations also predict that the concentrations of verapamil in the blood and bound verapamil in the tissue compartment rise with decreasing tip diameters. In contrast, the concentration of free verapamil in the tissue increases with increasing injection velocities. Conclusions: The novelty of this study includes verapamil metabolism in two-dimensional viscoelastic irregular viable skin and the nonlinear, specific, saturable, and reversible binding of verapamil in the tissue compartment. The tip diameter and the drug's injection velocity are thought to serve as regulatory parameters for the effectiveness and efficacy of MN-mediated therapy if the MN is robust enough to sustain the force needed to penetrate a wider tip into the skin.

Trends in Photopolymerization 3D Printing for Advanced Drug Delivery Applications

Since its invention in the 1980s, photopolymerization-based 3D printing has attracted significant attention for its capability to fabricate complex microstructures with high precision, by leveraging light patterning to initiate polymerization and cross-linking in liquid resin materials. Such precision makes it particularly suitable for biomedical applications, in particular, advanced and customized drug delivery systems. This review summarizes the latest advancements in photopolymerization 3D printing technology and the development of biocompatible and/or biodegradable materials that have been used or shown potential in the field of drug delivery. The drug loading methods and release characteristics of the 3D printing drug delivery systems are summarized. Importantly, recent trends in the drug delivery applications based on photopolymerization 3D printing, including oral formulations, microneedles, implantable devices, microrobots and recently emerging systems, are analyzed. In the end, the challenges and opportunities in photopolymerization 3D printing for customized drug delivery are discussed.

Microneedles: multifunctional devices for drug delivery, body fluid extraction, and bio-sensing

Microneedles represent a miniaturized mechanical structure with versatile applications, including transdermal drug delivery, vaccination, body-fluid extraction, and bio-sensing. Over the past two decades, microneedle-based devices have garnered considerable attention in the biomedicine field, exhibiting the potential for mitigating patient discomfort, enhancing treatment adherence, avoiding first-pass effects, and facilitating precise therapeutic interventions. As an application-oriented technology, the innovation of microneedles is generally carried out in response to a specific demand. Currently, three most common applications of microneedles are drug delivery, fluid extraction, and bio-sensing. This review focuses on the progress in the materials, fabrication techniques, and design of microneedles in recent years. On this basis, the progress and innovation of microneedles in the current research stage are introduced in terms of their three main applications.

A stimulus responsive microneedle-based drug delivery system for cancer therapy

The intricate nature of the tumor microenvironment (TME) results in the inefficient delivery of anticancer drugs within tumor tissues, significantly compromising the therapeutic effect of cancer treatment. To address this issue, transdermal drug delivery microneedles (MNs) with high mechanical strength have emerged. Such MNs penetrate the skin barrier, enabling efficient drug delivery to tumor tissues. This approach enhances drug bioavailability, while also mitigating concerns such as liver and kidney toxicity associated with intravenous and oral drug administration. Notably, stimulus responsive MNs designed for drug delivery have the capacity to respond to various biological signals and pathological changes. This adaptability enables them to exert therapeutic effects within the TME, exploiting biochemical variations and tailoring treatment strategies to suit tumor characteristics. The present review surveys recent advancements in responsive MN systems. This comprehensive analysis serves as a valuable reference for the prospective application of smart MN drug delivery systems in cancer therapy.

Emerging nitric oxide gas-assisted cancer photothermal treatment

Photothermal therapy (PTT) has garnered significant attention in recent years, but the standalone application of PTT still faces limitations that hinder its ability to achieve optimal therapeutic outcomes. Nitric oxide (NO), being one of the most extensively studied gaseous molecules, presents itself as a promising complementary candidate for PTT. In response, various nanosystems have been developed to enable the simultaneous utilization of PTT and NO-mediated gas therapy (GT), with the integration of photothermal agents (PTAs) and thermally-sensitive NO donors being the prevailing approach. This combination seeks to leverage the synergistic effects of PTT and GT while mitigating the potential risks associated with gas toxicity through the use of a single laser irradiation. Furthermore, additional internal or external stimuli have been employed to trigger NO release when combined with different types of PTAs, thereby further enhancing therapeutic efficacy. This comprehensive review aims to summarize recent advancements in NO gas-assisted cancer photothermal treatment. It commences by providing an overview of various types of NO donors and precursors, including those sensitive to photothermal, light, ultrasound, reactive oxygen species, and glutathione. These NO donors and precursors are discussed in the context of dual-modal PTT/GT. Subsequently, the incorporation of other treatment modalities such as chemotherapy (CHT), photodynamic therapy (PDT), alkyl radical therapy, radiation therapy, and immunotherapy (IT) in the creation of triple-modal therapeutic nanoplatforms is presented. The review further explores tetra-modal therapies, such as PTT/GT/CHT/PDT, PTT/GT/CHT/chemodynamic therapy (CDT), PTT/GT/PDT/IT, PTT/GT/starvation therapy (ST)/IT, PTT/GT/Ca2+ overload/IT, PTT/GT/ferroptosis (FT)/IT, and PTT/GT/CDT/IT. Finally, potential challenges and future perspectives concerning these novel paradigms are discussed. This comprehensive review is anticipated to serve as a valuable resource for future studies focused on the development of innovative photothermal/NO-based cancer nanotheranostics.

Advancements in Materials for 3D-Printed Microneedle Arrays: Enhancing Performance and Biocompatibility

The rapid advancement of 3D printing technology has revolutionized the fabrication of microneedle arrays (MNAs), which hold great promise in biomedical applications such as drug delivery, diagnostics, and therapeutic interventions. This review uniquely explores advanced materials used in the production of 3D-printed MNAs, including photopolymer resins, biocompatible materials, and composite resins, designed to improve mechanical properties, biocompatibility, and functional performance. Additionally, it introduces emerging trends such as 4D printing for programmable MNAs. By analyzing recent innovations, this review identifies critical challenges and proposes future directions to advance the field of 3D-printed MNAs. Unlike previous reviews, this paper emphasizes the integration of innovative materials with advanced 3D printing techniques to enhance both the performance and sustainability of MNAs.

Hydrogel-Forming Microneedles in the Management of Dermal Disorders Through a Non-Invasive Process: A Review

Microneedle (MN) technology has emerged as a promising approach for delivering therapeutic agents to the skin, offering significant potential in treating various dermal conditions. Among these technologies, hydrogel-forming microneedles (HFMNs) represent a transformative advancement in the management of dermal diseases through non-invasive drug delivery. These innovative devices consist of micrometer-sized needles made of native or crosslinked hydrophilic polymers, capable of penetrating the stratum corneum without damaging underlying tissues. Upon insertion, HFMNs rapidly absorb interstitial fluid, swelling to form a hydrogel conduit that enables the efficient transport of therapeutic agents directly into the dermal microcirculation. The non-invasive nature of HFMNs enhances patient compliance by eliminating the pain and discomfort associated with traditional hypodermic needles. This technology allows for the delivery of a wide range of drugs, including macromolecules and biomacromolecules, which are often difficult to administer dermally due to their size and polarity. Moreover, HFMNs provide controlled and regulated release profiles, enabling sustained therapeutic effects while minimizing systemic side effects. Additionally, HFMNs can be used for both drug delivery and real-time interstitial fluid monitoring, offering valuable insights into disease states and treatment responses. This dual functionality positions HFMNs as a versatile dermatology tool capable of effectively addressing various dermal complications. This review explores the potential use of polymeric biomaterials in HFMN fabrication and their application in treating major dermal disorders, such as acne, psoriasis, and other skin conditions. Furthermore, the review highlights the non-invasive nature of MN-based treatments, underscoring their potential to reduce patient discomfort and improve treatment adherence, as supported by the recent literature.

3D bioprinted microneedles: merging drug delivery and scaffold science for tissue-specific applications

INTRODUCTION

Three-Dimensional (3D) microneedles have recently gained significant attention due to their versatility, biocompatibility, enhanced permeation, and predictable behavior. The incorporation of biological agents into these 3D constructs has advanced the traditional microneedle into an effective platform for wide-ranging applications.

AREAS COVERED

This review discusses the current state of microneedle fabrication as well as the developed 3D printed microneedles incorporating labile pharmaceutical agents and biological materials for potential biomedical applications. The mechanical and processing considerations for the preparation of microneedles and the barriers to effective 3D printing of microneedle constructs have additionally been reviewed along with their therapeutic applications and potential for tissue engineering and regenerative applications. Additionally, the regulatory considerations for microneedle approval have been discussed as well as the current clinical trial and patent landscapes.

EXPERT OPINION

The fields of tissue engineering and regenerative medicine are evolving at a significant pace with researchers constantly focused on incorporating advanced manufacturing techniques for the development of versatile, complex, and biologically specific platforms. 3D bioprinted microneedles, fabricated using conventional 3D printing techniques, have resultantly provided an alternative to 2D bioscaffolds through the incorporation of biological materials within 3D constructs while providing further mechanical stability, increased bioactive permeation and improved innervation into surrounding tissues. This advancement therefore potentially allows for a more effective biomimetic construct with improved tissue-specific cellular growth for the enhanced treatment of physiological conditions requiring tissue regeneration and replacement.

Revolutionizing Eye Care: Exploring the Potential of Microneedle Drug Delivery

Microneedle technology revolutionizes ocular drug delivery by addressing challenges in treating ocular diseases. This review explores its potential impact, recent advancements, and clinical uses. This minimally invasive technique offers precise control of drug delivery to the eye, with various microneedle types showing the potential to penetrate barriers in the cornea and sclera, ensuring effective drug delivery. Recent advancements have improved safety and efficacy, offering sustained and controlled drug delivery for conditions like age-related macular degeneration and glaucoma. While promising, challenges such as regulatory barriers and long-term biocompatibility persist. Overcoming these through interdisciplinary research is crucial. Ultimately, microneedle drug delivery presents a revolutionary method with the potential to significantly enhance ocular disease treatment, marking a new era in eye care.

Visualization of the degradation of long-acting microneedles and correlation of drug release in vivo based on FRET mechanism

This study introduces a live imaging technique for real-time, non-invasive monitoring of drug release from long-acting microneedles using FRET (Fluorescence Resonance Energy Transfer). Employing Cy5.5 and Cy7 as FRET pairs and levonorgestrel as the model drug, we fabricated microneedles with varying PLGA molecular weights, demonstrating distinct release profiles. The FRET-PLGA-10-MN demonstrated a rapid drug release profile, reaching nearly complete release within a two-day period, while FRET-PLGA-30-MN showed a sustained release over four days. Sensitized Emission FRET (SE-FRET) optimized the imaging process, providing a robust correlation between FRET signals and drug absorption. This method surpasses traditional pharmacokinetic studies by offering a more efficient and comprehensive analysis of microneedle release dynamics in vivo, paving the way for enhanced long-acting microneedle design and therapeutic outcomes. STATEMENT OF SIGNIFICANCE: 1. FRET technology was applied to microneedle drug delivery system for the first time, which realized real-time, quantitative and non-invasive monitoring of drug release process. 2. The long-term microneedle technique was combined with sensitized emission method, and the FRET remaining ratio was innovatively used to investigate the FRET characteristics of microneedles, and the fluorescence ratio of FRET and donor double-channel was quantitatively calculated. 3. The correlation between visual fluorescence images of FRET effect and semi-quantitative calculation results based on fluorescence intensity and drug release in vivo with drug-loaded microneedles was analyzed.

Dissolving Microneedles Patch: A Promising Approach for Advancing Transdermal Delivery of Antischizophrenic Drug

OBJECTIVE

Microneedles (MNs) are minimally invasive transdermal drug delivery systems capable of penetrating the stratum corneum to overcome the barrier properties. The primary objective of this research was to prepare dissolving microneedle patches (DMNP) loaded with quetiapine (QTP).

METHODS

DMNP were fabricated employing the solvent casting technique, utilizing various polymer feed ratios including polyvinyl alcohol (PVA), polyvinylpyrrolidone K30 (PVP-K30), and polylactide-co-glycolide (PLGA) polymers. The loaded DMNP with QTP underwent a comprehensive characterization process encompassing assessments for compatibility, thickness, insertion potential, morphology, thermal behavior, X-ray diffraction, ex-vivo permeation, skin irritation, and histopathological changes.

RESULTS

FTIR studies confirmed the compatibility of QTP with the microneedle patch composites. The thickness of the drug-loaded DMNP ranged from 0.67 mm to 0.97 mm. These microneedles exhibited an impressive penetration depth of 480 μm, with over 80% of the needles maintaining their original shape after piercing Parafilm-M. SEM analysis of the optimized DMNP-2 revealed the formation of sharp-tipped and uniformly surfaced needles, measuring 570 μm in length. Remarkably, the microneedles did not elicit any signs of irritation upon application of the prepared DMNP. The DMNP-2 showcased an impressive cumulative ex-vivo permeation of QTP, reaching 17.82 µg/cm2/hr. Additionally, histopathological assessment of vital organs in rabbits attested to the safety profile of the formulated microneedle patches.

CONCLUSIONS

In conclusion, the developed microneedle patch represents a promising strategy for enhancing the transdermal delivery of QTP. This innovative approach has the potential to increase patient compliance, offering a more efficient and patient-friendly method of administering QTP.

Cutting-edge microneedle innovations: Transforming the landscape of cardiovascular and metabolic disease management

Cardiovascular diseases (CVDs) and metabolic disorders (MDs) have surfaced as formidable challenges to global health, significantly imperiling human well-being. Recently, microneedles (MNs) have garnered substantial interest within the realms of CVD and MD research. Offering a departure from conventional diagnostic and therapeutic methodologies, MNs present a non-invasive, safe, and user-friendly modality for both monitoring and treatment, thereby marking substantial strides and attaining pivotal achievements in this avant-garde domain, while also unfurling promising avenues for future inquiry. This thorough review encapsulates the latest developments in employing MNs for both the surveillance and management of CVDs and MDs. Initially, it succinctly outlines the foundational principles and approaches of MNs in disease surveillance and therapy. Subsequently, it delves into the pioneering utilizations of MNs in the surveillance and management of CVDs and MDs. Ultimately, this discourse synthesizes and concludes the primary findings of this investigation, additionally prognosticating on the trajectory of MN technology.

Light in evaluation of molecular diffusion in tissues: Discrimination of pathologies

The evaluation of the diffusion properties of different molecules in tissues is a subject of great interest in various fields, such as dermatology/cosmetology, clinical medicine, implantology and food preservation. In this review, a discussion of recent studies that used kinetic spectroscopy measurements to evaluate such diffusion properties in various tissues is made. By immersing ex vivo tissues in agents or by topical application of those agents in vivo, their diffusion properties can be evaluated by kinetic collimated transmittance or diffuse reflectance spectroscopy. Using this method, recent studies were able to discriminate the diffusion properties of agents between healthy and diseased tissues, especially in the cases of cancer and diabetes mellitus. In the case of cancer, it was also possible to evaluate an increase of 5% in the mobile water content from the healthy to the cancerous colorectal and kidney tissues. Considering the application of some agents to living organisms or food products to protect them from deterioration during low temperature preservation (cryopreservation), and knowing that such agent inclusion may be reversed, some studies in these fields are also discussed. Considering the broadband application of the optical spectroscopy evaluation of the diffusion properties of agents in tissues and the physiological diagnostic data that such method can acquire, further studies concerning the optimization of fruit sweetness or evaluation of poison diffusion in tissues or antidote application for treatment optimization purposes are indicated as future perspectives.

Albumin-Based Microneedles for Spatiotemporal Delivery of Temozolomide and Niclosamide to Resistant Glioblastoma

Glioblastoma (GBM) is the most common and aggressive malignant brain tumor. Standard therapy includes maximal surgical resection, radiotherapy, and adjuvant temozolomide (TMZ) administration. However, the rapid development of TMZ resistance and the impermeability of the blood-brain barrier (BBB) significantly hinder the therapeutic efficacy. Herein, we developed spatiotemporally controlled microneedle patches (BMNs) loaded with TMZ and niclosamide (NIC) to overcome GBM resistance. We found that hyaluronic acid (HA) increased the viscosity of bovine serum albumin (BSA) and evidenced that concentrations of BSA/HA exert an impact degradation rates exposure to high-temperature treatment, showing that the higher BSA/HA concentrations result in slower drug release. To optimize drug release rates and ensure synergistic antitumor effects, a 15% BSA/HA solution constituting the bottoms of BMNs was chosen to load TMZ, showing sustained drug release for over 28 days, guaranteeing long-term DNA damage in TMZ-resistant cells (U251-TR). Needle tips made from 10% BSA/HA solution loaded with NIC released the drug within 14 days, enhancing TMZ's efficacy by inhibiting the activity of O6-methylguanine-DNA methyltransferase (MGMT). BMNs exhibit superior mechanical properties, bypass the BBB, and gradually release the drug into the tumor periphery, thus significantly inhibiting tumor proliferation and expanding median survival in mice. The on-demand delivery of BMNs patches shows a strong translational potential for clinical applications, particularly in synergistic GBM treatment.

NIR-Remote Selectively Triggered Buprenorphine Hydrochloride Release from Microneedle Patches for the Treatment of Neuropathic Pain

Neuropathic pain is a prevalent form of intermittent chronic pain, affecting approximately 7-10% of the global population. However, the current clinical administration methods, such as injection and oral administration, are mostly one-time administration, which cannot achieve accurate control of pain degree and drug dose. Herein, we developed near-infrared (NIR) light-responsive microneedle patches (MNPs) to spatiotemporally control the drug dose released to treat neuropathic pain according to the onset state. The mechanism of action utilizes upconversion nanoparticles to convert NIR light into visible and ultraviolet light. This conversion triggers the rapid rotation of the azobenzene molecular motor in the mesoporous material, enabling the on-demand controlled release of a drug dose. Additionally, MNs are used to overcome the barrier of the stratum corneum in a minimally invasive and painless manner, effectively promoting the transdermal penetration of drug molecules. The effectiveness of these patches has been demonstrated through significant results. Upon exposure to NIR light for five consecutive cycles, with each cycle lasting 30 s, the patches achieved a precise release of 318 μg of medication. In a mouse model, maximum pain relief was observed within 1 h of one cycle of NIR light exposure, with the effects lasting up to 6 h. The same level of precise treatment efficacy was maintained for subsequent pain episodes with similar light exposure. The NIR-controlled drugs precision-released MNPs provide a novel paradigm for the treatment of intermittent neuropathic pain.

Hybrid Microneedle-Mediated Transdermal Delivery of Atorvastatin Calcium-Loaded Polymeric Micelles for Hyperlipidemia Therapy

Hyperlipidemia has been a huge challenge to global health, leading to the cardiovascular disease, hypertension, and diabetes. Atorvastatin calcium (AC), a widely prescribed drug for hyperlipidemia, faces huge challenges with oral administration due to poor water solubility and hepatic first-pass effects, resulting in low therapeutic efficacy. In this work, we designed and developed a hybrid microneedle (MN) patch system constructed with soluble poly(vinyl alcohol) (PVA) and AC-loaded polymeric micelles (AC@PMs) for transdermal delivery of AC to enhance the hyperlipidemia therapy. We first prepared various AC@PM formulations self-assembled from mPEG-PLA and mPEG-PLA-PEG block copolymers using a dialysis method and evaluated the physicochemical properties in combination with experiment skills and dissipative particle dynamics (DPD) simulations. Then, we encapsulated the AC@PMs into the PVA MN patch using a micromold filling method, followed by characterizing the performances, especially the structural stability, mechanical performance, and biosafety. After conducting in vivo experiments using a hyperlipidemic rat model, our findings revealed that the hybrid microneedle-mediated administration exhibited superior therapeutic efficacy when compared to oral delivery methods. In summary, we have successfully developed a hybrid microneedle (MN) patch system that holds promising potential for the efficient transdermal delivery of hydrophobic drugs.

Transdermal microneedle patches as a promising drug delivery system for anti-obesogenic molecules

Obesity, characterized by excessive storage of lipids, has become a global pandemic with high incidence levels, and its forecast is not encouraging. Currently, there are different strategies to treat obesity; however, these conventional methods have various limitations. Lifestyle changes may result in poor outcomes due to the complexity of obesity causes, pharmaceutic treatments produce severe side effects, and bariatric surgery is highly invasive. In the search for alternative treatments to fight obesity, transdermal drug delivery systems of anti-obesogenic molecules have gained particular attention. However, the diffusion of molecules through the skin is the main drawback due to the characteristics of different layers of the skin, principally the stratum corneum and its barrier-like behavior. In this sense, microneedles patches (MP) have emerged to overcome this limitation by piercing the skin and allowing drug delivery inside the body. Although MP have been studied for some years, it was not until about 2017 that their potential as anti-obesogenic treatment was reported. This article aims to summarize and analyze the strategies employed to produce MP and to embed the active molecules against obesity. Special attention is focused on the microneedle's material, geometry, array, and additional delivery strategies, like nanoencapsulation. MP are a promising tool to develop an easy-access treatment, avoiding the digestive tract and with the capacity to enhance the anti-obesogenic activity by delivering one or more active molecules.

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.

Polymeric Microneedles for Health Care Monitoring: An Emerging Trend

Bioanalyte collection by blood draw is a painful process, prone to needle phobia and injuries. Microneedles can be engineered to penetrate the epidermal skin barrier and collect analytes from the interstitial fluid, arising as a safe, painless, and effective alternative to hypodermic needles. Although there are plenty of reviews on the various types of microneedles and their use as drug delivery systems, there is a lack of systematization on the application of polymeric microneedles for diagnosis. In this review, we focus on the current state of the art of this field, while providing information on safety, preclinical and clinical trials, and market distribution, to outline what we believe will be the future of health monitoring.

Assessing the structural stability and drug encapsulation efficiency of poly(ethylene glycol)-poly(L-lactic acid) nanoparticles loaded with atorvastatin calcium: Based on dissipative particle dynamics

Block polymer micelles have been proven highly biocompatible and effective in improving drug utilization for delivering atorvastatin calcium. Therefore, it is of great significance to measure the stability of drug-loading nano micelles from the perspective of block polymer molecular sequence design, which would provide theoretical guidance for subsequent clinical applications. This study aims to investigate the structural stability of drug-loading micelles formed by two diblock/triblock polymers with various block sequences through coarse-grained dissipative particle dynamics (DPD) simulations. From the perspectives of the binding strength of poly(L-lactic acid) (PLLA) and polyethylene glycol (PEG) in nanoparticles, hydrophilic bead surface coverage, and the morphological alteration of nanoparticles induced by shear force, the ratio of hydrophilic/hydrophobic sequence length has been observed to affect the stability of nanoparticles. We have found that for diblock polymers, PEG3kda-PLLA2kda has the best stability (corresponding hydrophilic coverage ratio is 0.832), while PEG4kda-PLLA5kda has the worst (coverage ratio 0.578). For triblock polymers, PEG4kda-PLLA2kda-PEG4kda has the best stability (0.838), while PEG4kda-PLLA5kda-PEG4kda possesses the worst performance (0.731), and the average performance on stability is better than nanoparticles composed of diblock polymers.

Aggregation-induced emission photosensitizer microneedles for enhanced melanoma photodynamic therapy

The incidence and mortality rates of skin melanoma have been increasing annually. Photodynamic therapy (PDT) enables effective destruction of tumor cells while minimizing harm to normal cells. However, traditional photosensitizers (PSs) suffer from photobleaching, photodegradation and the aggregation-caused quenching (ACQ) effect, and it is challenging for light to reach the deep layers of the skin to maximize the efficacy of PSs. Herein, we developed dissolving microneedles (MNs) loaded with PSs of TPE-EPy@CB[7] through supramolecular assembly. The PSs effectively enhanced the type-I reactive oxygen species (ROS) generation capacity, with a concentration of 2 μM possessing nearly half of the tumor cell-killing ability under 10 min white light irradiation. The MNs were successfully pierced into the targeted site for precise drug delivery. Additionally, the conical structure of the MNs, as well as the lens-like structure after dissolution, facilitated the transmission of light in the subcutaneous tissue, achieving significant inhibition of tumor growth with a tumor suppression rate of 97.8% and no systemic toxicity or side effects in melanoma mice. The results demonstrated the potent melanoma inhibition and biosafety of this treatment approach, exhibiting a new and promising strategy to conquer malignant melanoma.

Core-shell structured microneedles with programmed drug release functions for prolonged hyperuricemia management

An appropriate non-oral platform via transdermal delivery of drugs is highly recommended for the treatment of hyperuricemia. Herein, a core-shell structured microneedle patch with programmed drug release functions was designed to regulate serum uric acid (SUA) levels for prolonged hyperuricemia management. The patch was fabricated using a three-step casting method. Allopurinol (AP), an anti-hyperuricemic drug, was encapsulated within the carboxymethyl cellulose (CMC) layer, forming the "shell" of the MNs. The MN's inner core was composed of polyvinylpyrrolidone (PVP) loaded with urate oxidase-calcium peroxide nanoparticles (UOx-CaO2 NPs). When the as-fabricated core-shell structured microneedles were inserted into the skin, the loaded AP was first released immediately to effectively inhibit the production of SUA due to the water solubility of CMC. Subsequently, the internal SUA was further metabolized by UOx, leading to exposure of CaO2 NPs. The sustained release of UOx accompanied by the decomposition of CaO2 NPs contributed to maintaining a state of normal uric acid levels over an extended period. More attractively, uric acid could be oxidized due to the strong oxidant of CaO2, which was beneficial to the continuous consumption of uric acid. In vivo results showed that the as-fabricated MNs exhibited an excellent anti-hyperuricemia effect to reduce SUA levels to the normal state within 3 h and maintain the normouricemia state for 12 h. In addition, the levels of creatinine (Cr) and blood urea nitrogen (BUN) in the serum remained within the normal range, and the activities of adenosine deaminase (ADA) and xanthine oxidase (XOD) in the liver were effectively inhabited, mitigating the risk of liver and kidney damage for clinical anti-hyperuricemia management.

Emerging Trends in Hybrid Nanoparticles: Revolutionary Advances and Promising Biomedical Applications

Modern nanostructures must fulfill a wide range of functions to be valuable, leading to the combination of various nano-objects into hierarchical assemblies. Hybrid Nanoparticles (HNPs), comprised of multiple types of nanoparticles, are emerging as nanoscale structures with versatile applications. HNPs offer enhanced medical benefits compared to basic combinations of distinct components. They address the limitations of traditional nanoparticle delivery systems, such as poor water solubility, nonspecific targeting, and suboptimal therapeutic outcomes. HNPs also facilitate the transition from anatomical to molecular imaging in lung cancer diagnosis, ensuring precision. In clinical settings, the selection of nanoplatforms with superior reproducibility, cost-effectiveness, easy preparation, and advanced functional and structural characteristics is paramount. This study aims toextensively examine hybrid nanoparticles, focusing on their classification, drug delivery mechanisms, properties of hybrid inorganic nanoparticles, advancements in hybrid nanoparticle technology, and their biomedical applications, particularly emphasizing the utilization of smart hybrid nanoparticles. PHNPs enable the delivery of numerous anticancer, anti-leishmanial, and antifungal drugs, enhancing cellular absorption, bioavailability, and targeted drug delivery while reducing toxic side effects.