A Sample and Detection Microneedle Patch for Psoriasis MicroRNA Biomarker Analysis in Interstitial Fluid

In situ enrichment and ultrasensitive analysis of interstitial fluid miRNA enabled by hydrogel microneedles coupled with DNA-gated metal-organic frameworks

A novel strategy combining GelMA hydrogel microneedles and DNA-gated MOFs for sensitive miRNA detection in skin interstitial fluid (ISF) is reported. GelMA MNs efficiently extract ISF, while DNA-gated MOFs offer dual-mode detection via fluorescence and SERS. In vivo results demonstrate successful miRNA extraction and sensitive biomarker detection, advancing minimally invasive diagnostics and real-time health monitoring.

Molecular and histological evidence for the biocompatibility of PEDOT-coated microneedles in human skin

The increasing demand for real-time, continuous health monitoring has driven improvements in wearable and skin-attachable devices, particularly in sensing vital body signs and biomarkers. Research on conducting polymers (CPs) in these devices is also growing due to their low cost, flexibility, and versatile fabrication. However, despite their widespread use and claims of biocompatibility, there are limited studies on the biocompatibility of CPs in human skin, and those that exist have only been conducted using cell cytotoxicity or animal testing, lacking proper and comprehensive assessments. To address this critical gap, this study investigates the biocompatibility of CPs, represented by poly(3,4-ethylenedioxythiophene) (PEDOT), in excised human skin. In addition to the pathological evaluation of skin biopsies, a novel assessment of CP's impact on the expression of stress-related gene markers is reported, providing a comprehensive analysis at both the tissue and molecular levels. PEDOT-coated microneedles were implanted in the skin for transdermal interrogation, and after 24 hours of incubation, the exposed skin was studied using histology and RT-PCR. This paper offers fundamental insights for future CP-engineered devices in skin applications, contributing valuable data to the materials community regarding the true biocompatibility of these widely used materials.

Toward precision medicine: End-to-end design and construction of integrated microneedle-based theranostic systems

With the growing demand for precision medicine and advancements in microneedle technology, microneedle-based drug delivery systems have evolved into integrated theranostic platforms. However, the development of these systems is currently limited by the absence of clear conclusions and standardized construction strategies. The end-to-end concept offers an innovative approach to theranostic systems by creating a seamless process that integrates target sampling, sensing, analysis, and on-demand drug delivery. This approach optimizes each step based on data from the others, effectively eliminating the traditional separation between drug delivery and disease monitoring. Furthermore, by incorporating artificial intelligence and machine learning, these systems can enhance reliability and efficiency in disease management, paving the way for more personalized and effective healthcare solutions. Based on the concept of end-to-end and recent advancements in theranostic systems, nanomaterials, electronic components, micro-composites, and data science, we propose a modular strategy for constructing integrated microneedle-based theranostic systems by detailing the methods and functions of each critical component, including monitoring, decision-making, and on-demand drug delivery units, though the total number of units might vary depending on the specific application. Notably, decision-making units are emerging trends for fully automatic and seamless systems and featured for integrated microneedle-based theranostic systems, which serve as a bridge of real-time monitoring, on-demand drug delivery, advanced electronic engineering, and data science for personalized disease management and remote medical application. Additionally, we discuss the challenges and prospects of integrated microneedle-based theranostic systems for precision medicine and clinical application.

Hydrogel-Forming Microneedles and Applications in Interstitial Fluid Diagnostic Devices

Hydrogel-forming microneedles are constructed from or coated with polymeric, hydrophilic materials that swell upon insertion into the skin. Designed to dissolve or disintegrate postinsertion, these microneedles can deliver drugs, vaccines, or other therapeutics. Recent advancements have broadened their application scope to include the collection, transport, and extraction of dermal interstitial fluid (ISF) for medical diagnostics. This review presents a brief introduction to the characteristics of dermal ISF, methods for extraction and sampling, and critical assessment of the state-of-the-art in hydrogel-forming microneedles for ISF diagnostics. Key factors are evaluated including material composition, swelling behavior, biocompatibility, and mechanical strength necessary for effective microneedle performance and ISF collection. The review also discusses successful examples of dermal ISF assays and microneedle sensor integrations, highlighting notable achievements, identifying research opportunities, and addressing challenges with potential solutions. Despite the predominance of synthetic hydrogels in reported hydrogel-forming microneedle technologies due to their favorable swelling and gelation properties, there is a significant variety of biopolymers and composites reported in the literature. The field lacks consensus on the optimal material, composition, or fabrication methods, though emerging evidence suggests that processing and fabrication techniques are critical to the performance and utility of hydrogel-forming microneedles for ISF diagnostics.

Recent Progress and Opportunities of Wearable Non-Invasive Epidermal Sensors for Skin Disease Diagnosis

With deteriorating environment and increased stress in modern life, skin diseases have become the fourth leading cause of nonfatal and chronic diseases. An early diagnosis might improve the chances of a successful treatment. Wearable epidermal sensors have been emerged as new non-invasive tools for clinical practice and research in dermatology, which can act as a complement to the otherwise mostly visual and tactile judgments. This review discusses the recent progress and opportunities of wearable epidermal sensors for skin disease diagnosis. The configuration, material choice, and fundamental platforms of wearable epidermal sensors are first summarized. Then, their emerging application in monitoring skin diseases is demonstrated by detecting skin hardness, skin hydration, and biomakers. With the advances highlighted here and the ongoing research efforts, the continuous breakthrough in wearable epidermal sensors and their attractive application in skin disease management is foreseeable in the future.

Advances in Research of Hydrogel Microneedle-Based Delivery Systems for Disease Treatment

Microneedles (MNs), composed of multiple micron-scale needle-like structures attached to a base, offer a minimally invasive approach for transdermal drug delivery by penetrating the stratum corneum and delivering therapeutic agents directly to the epidermis or dermis. Hydrogel microneedles (HMNs) stand out among various MN types due to their excellent biocompatibility, high drug-loading capacity, and tunable drug-release properties. This review systematically examines the matrix materials and fabrication methods of HMN systems, highlighting advancements in natural and synthetic polymers, and explores their applications in treating conditions such as wound healing, hair loss, cardiovascular diseases, and cancer. Furthermore, the potential of HMNs for disease diagnostics is discussed. The review identifies key challenges, including limited mechanical strength, drug-loading efficiency, and lack of standardization, while proposing strategies to overcome these issues. With the integration of intelligent design and enhanced control over drug dosage and safety, HMNs are poised to revolutionize transdermal drug delivery and expand their applications in personalized medicine.

Engineering with Biomedical Sciences Changing the Horizon of Healthcare-A Review

In the dynamic realm of healthcare, the convergence of engineering and biomedical sciences has emerged as a pivotal frontier. In this review we go into specific areas of innovation, including medical imaging and diagnosis, developments in biomedical sensors, and drug delivery systems. Wearable biosensors, non-wearable biosensors, and biochips, which include gene chips, protein chips, and cell chips, are all included in the scope of the topic that pertains to biomedical sensors. Extensive research is conducted on drug delivery systems, spanning topics such as the integration of computer modeling, the optimization of drug formulations, and the design of delivery devices. Furthermore, the paper investigates intelligent drug delivery methods, which encompass stimuli-responsive systems such as temperature, redox, pH, light, enzyme, and magnetic responsive systems. In addition to that, the review goes into topics such as tissue engineering, regenerative medicine, biomedical robotics, automation, biomechanics, and the utilization of green biomaterials. The purpose of this analysis is to provide insights that will enhance continuing research and development efforts in engineering-driven biomedical breakthroughs, ultimately contributing to the improvement of healthcare. These insights will be provided by addressing difficulties and highlighting future prospects.

Microneedles as transdermal drug delivery system for enhancing skin disease treatment

Microneedles (MNs) serve as a revolutionary paradigm in transdermal drug delivery, heralding a viable resolution to the formidable barriers presented by the cutaneous interface. This review examines MNs as an advanced approach to enhancing dermatological pathology management. It explores the complex dermis structure and highlights the limitations of traditional transdermal methods, emphasizing MNs' advantage in bypassing the stratum corneum to deliver drugs directly to the subdermal matrix. The discourse outlines the diverse typologies of MNs, including solid, coated, hollow, hydrogel, and dissolvable versions. Each type is characterized by its unique applications and benefits. The treatise details the deployment of MNs in the alleviation of cutaneous cancers, the administration of inflammatory dermatoses such as psoriasis and atopic dermatitis, and their utility in wound management. Additionally, the paper contemplates the prospects of MNs within the realm of aesthetic dermatology and the burgeoning market traction of cosmetic MN formulations. The review summarizes the scientific and commercial challenges to the clinical adoption of MN therapeutics, including dosage calibration, pharmacodynamics, biocompatibility, patient compliance, sterilization, mass production, and regulatory oversight. It emphasizes the need for ongoing research, innovation, and regulatory harmonization to overcome these obstacles and fully realize MNs' potential in treating skin diseases and improving patient welfare.

Microneedle patches incorporating zinc-doped mesoporous silica nanoparticles loaded with betamethasone dipropionate for psoriasis treatment

Treating psoriasis presents a major clinical challenge because of the limitations associated with traditional topical glucocorticoid therapy. This study introduced a drug delivery system utilizing zinc-doped mesoporous silica nanoparticle (Zn-MSN) and microneedle (MN), designed to enhance drug utilization for prolonged anti-inflammatory and anti-itch effects. The MN system facilitated the transdermal delivery of betamethasone dipropionate (BD), allowing its slow release. The BD@Zn-MSN-MN system promoted the polarization of macrophages towards the anti-inflammatory M2 phenotype, achieving superior anti-inflammatory effects compared to the clinically used BD cream. Additionally, this study demonstrated that BD@Zn-MSN-MN could further alleviate itching in psoriasis-afflicted mice by decreasing the excitability of the transient receptor potential vanilloid V1 (TRPV1) ion channel positive neurons and reducing the release of calcitonin gene-related peptide (CGRP) in the dorsal root ganglion (DRG). These findings offer new insights and effective therapeutic options for the future design of transdermal drug delivery for psoriasis.

Rapid miRNA detection in skin interstitial fluid using a hydrogel microneedle patch integrated with DNA probes and graphene oxide

MicroRNA (miRNA) is a type of short, non-coding nucleic acid molecule that plays essential roles in diagnosing and prognosing various types of cancer. MiRNA is abundantly present in skin interstitial fluid (ISF), providing real-time and localized physiological information. Hydrogel microneedle (HMN) patches enable miRNA collection in a fast, pain-free, minimally invasive, and user-friendly manner. In this study, we introduced a fluorescence-based HMN assay, namely the HMN-miR sensor, composed of methacrylated hyaluronic acid (MeHA) and a graphene oxide-probe DNA (GO.pDNA) conjugate for miR21 and miR210 detection. The HMN-miR sensor demonstrates excellent skin penetration efficiency, rapid ISF collection capability, and sufficient miRNA detection and sequence identification specificity. The HMN-miR sensor facilitates a new assay that, with further optimization, could be applied in future clinical settings. Its simple fabrication process and excellent biocompatibility give it significant potential for various clinical uses, such as personalized cancer treatment and monitoring the healing progress of burn wounds.

Semi-invasive wearable clinic: Solution-processed smart microneedle electronics for next-generation integrated diagnosis and treatment

The integrated smart electronics for real-time monitoring and personalized therapy of disease-related analytes have been gradually gaining tremendous attention. However, human tissue barriers, including the skin barrier and brain-blood barrier, pose significant challenges for effective biomarker detection and drug delivery. Microneedle (MN) electronics present a promising solution to overcome these tissue barriers due to their semi-invasive structures, enabling effective drug delivery and target-analyte detection without compromising the tissue configuration. Furthermore, MNs can be fabricated through solution processing, facilitating large-scale manufacturing. This review provides a comprehensive summary of the recent three-year advancements in smart MNs development, categorized as follows. First, the solution-processed technology for MNs is introduced, with a focus on various printing technologies. Subsequently, smart MNs designed for sensing, drug delivery, and integrated systems combining diagnosis and treatment are separately summarized. Finally, the prospective and promising applications of next-generation MNs within mediated diagnosis and treatment systems are discussed.

Microneedles-Based Theranostic Platform: From the Past to the Future

Fully integrated theranostic devices are highly esteemed in clinical applications, offering immense potential in real-time disease monitoring and personalized care. Microneedles (MNs), as innovative and wearable devices, boast important advantages in biosensing and therapy, thus holding significant promise in the advancement of diagnostic and therapeutic platforms. Encouragingly, advancements in electrochemical sensing technology, micronano fabrication, and biocompatible materials are propelling momentum for MNs-based closed-loop systems, enhancing detection capabilities, biocompatibility, and cost-effectiveness. Moreover, the notable progress in integrating MN chips with other biochips signifies a frontier for growth. Successful clinical trials in target molecule monitoring and drug delivery domains herald excellent clinical translational prospects for the aforementioned theranostic platform. Finally, we delineate both challenges and opportunities in the development of integrated diagnostic and therapeutic MN systems, including continuous monitoring, intelligent control algorithms, safety, and regulatory considerations.

Sensing patches for biomarker identification in skin-derived biofluids

In conventional clinical disease diagnosis and screening based on biomarker detection, most analysis samples are collected from serum, blood. However, these invasive collection methods require specific instruments, professionals, and may lead to infection risks. Additionally, the diagnosis process suffers from untimely results. The identification of skin-related biomarkers plays an unprecedented role in early disease diagnosis. More importantly, these skin-mediated approaches for collecting biomarker-containing biofluid samples are noninvasive or minimally invasive, which is more preferable for point-of-care testing (POCT). Therefore, skin-based biomarker detection patches have been promoted, owing to their unique advantages, such as simple fabrication, desirable transdermal properties and no requirements for professional medical staff. Currently, the skin biomarkers extracted from sweat, interstitial fluid (ISF) and wound exudate, are achieved with wearable sweat patches, transdermal MN patches, and wound patches, respectively. In this review, we detail these three types of skin patches in biofluids collection and diseases-related biomarkers identification. Patch classification and the corresponding manufacturing as well as detection strategies are also summarized. The remaining challenges in clinical applications and current issues in accurate detection are discussed for further advancement of this technology (Scheme 1).

Integrating microneedles and sensing strategies for diagnostic and monitoring applications: The state of the art

Microneedles (MNs) offer minimally-invasive access to interstitial fluid (ISF) - a potent alternative to blood in terms of monitoring physiological analytes. This property is particularly advantageous for the painless detection and monitoring of drugs and biomolecules. However, the complexity of the skin environment, coupled with the inherent nature of the analytes being detected and the inherent physical properties of MNs, pose challenges when conducting physiological monitoring using this fluid. In this review, we discuss different sensing mechanisms and highlight advancements in monitoring different targets, with a particular focus on drug monitoring. We further list the current challenges facing the field and conclude by discussing aspects of MN design which serve to enhance their performance when monitoring different classes of analytes.

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.

A Review of Recent Advances in Microneedle-Based Sensing within the Dermal ISF That Could Transform Medical Testing

Interstitial fluid (ISF) has attracted extensive attention in an extremely wide range of areas due to its unique advantages, such as portability, high precision, comfortable operation, and superior stability. In recent years, the microneedle (MN) technique has been considered to be an excellent tool for extracting ISF because it is painless and noninvasive. Recent reports have shown that MN has good application prospects in ISF extraction. In this review, we provide comprehensive and in-depth insight into integrated MN devices for ISF detection, covering the basic structure as well as the fabrication of integrated MN devices and various applications in ISF extraction. Challenges and prospects are highlighted, with a discussion on how to transition such MN-integrated devices toward personalized healthcare monitoring systems.

Cell Viability Assessment of PEDOT Conducting Polymer-Coated Microneedles for Skin Sampling

Recently, transdermal monitoring and drug delivery have gained much interest, owing to the introduction of the minimally invasive microneedle (MN) device. The advancement of electroactive MNs electrically assisted in the capture of biomarkers or the triggering of drug release. Recent works have combined conducting polymers (CPs) onto MNs owing to the soft nature of the polymers and their tunable ionic and electronic conductivity. Though CPs are reported to work safely in the body, their biocompatibility in the skin has been insufficiently investigated. Furthermore, during electrical biasing of CPs, they undergo reduction or oxidation, which in practical terms leads to release/exchange of ions, which could pose biological risks. This work investigates the viability and proliferation of skin cells upon exposure to an electrochemically biased MN pair comprising two differently doped poly(3,4-ethylenedioxy-thiophene) (PEDOT) polymers that have been designed for skin sampling use. The impact of biasing on human keratinocytes and dermal fibroblasts was determined at different initial cell seeding densities and incubation periods. Indirect testing was employed, whereby the culture media was first exposed to PEDOTs prior to the addition of this extract to cells. In all conditions, both unbiased and biased PEDOT extracts showed no cytotoxicity, but the viability and proliferation of cells cultured at a low cell seeding density were lower than those of the control after 48 h of incubation.

Microneedle systems: cell, exosome, and nucleic acid based strategies

Cells, exosomes, and nucleic acids play crucial roles in biomedical engineering, holding substantial clinical potential. However, their utility is often hindered by various drawbacks, including cellular immunogenicity, and instability of exosomes and nucleic acids. In recent years, microneedle (MN) technology has revolutionized drug delivery by offering minimal invasiveness and remarkable versatility. MN has emerged as an ideal platform for the extraction, storage, and delivery of these biological components. This review presents a comprehensive overview of the historical progression and recent advances in the field of MN. Specifically, it highlights the current applications of cell-, exosome-, and nucleic acid-based MN systems, while presenting prevailing research challenges. Additionally, the review provides insights into the prospects of MN in this area, aiming to provide new ideas for researchers and facilitate the clinical translation of MN technology.

Dissolving and Swelling Hydrogel-Based Microneedles: An Overview of Their Materials, Fabrication, Characterization Methods, and Challenges

Polymeric hydrogels are a complex class of materials with one common feature-the ability to form three-dimensional networks capable of imbibing large amounts of water or biological fluids without being dissolved, acting as self-sustained containers for various purposes, including pharmaceutical and biomedical applications. Transdermal pharmaceutical microneedles are a pain-free drug delivery system that continues on the path to widespread adoption-regulatory guidelines are on the horizon, and investments in the field continue to grow annually. Recently, hydrogels have generated interest in the field of transdermal microneedles due to their tunable properties, allowing them to be exploited as delivery systems and extraction tools. As hydrogel microneedles are a new emerging technology, their fabrication faces various challenges that must be resolved for them to redeem themselves as a viable pharmaceutical option. This article discusses hydrogel microneedles from a material perspective, regardless of their mechanism of action. It cites the recent advances in their formulation, presents relevant fabrication and characterization methods, and discusses manufacturing and regulatory challenges facing these emerging technologies before their approval.

Soft microfiber-based hollow microneedle array for stretchable microfluidic biosensing patch with negative pressure-driven sampling

Wearable point-of-care testing devices are essential for personalized and decentralized healthcare. They can collect biofluid samples from the human body and use an analyzer to detect biomolecules. However, creating an integrated system is challenging due to the difficulty of achieving conformality to the human body, regulating the collection and transport of biofluids, developing a biosensor patch capable of precise biomolecule detection, and establishing a simple operation protocol that requires minimal wearer attention. In this study, we propose using a hollow microneedle (HMN) based on soft hollow microfibers and a microneedle-integrated microfluidic biosensor patch (MIMBP) capable of integrated blood sampling and electrochemical biosensing of biomolecules. The soft MIMBP includes a stretchable microfluidic device, a flexible electrochemical biosensor, and a HMN array made from flexible hollow microfibers. The HMNs are fabricated by electroplating flexible and mechanically durable hollow microfibers made from a nanocomposite matrix of polyimide, a poly (vinylidene fluoride-co-trifluoroethylene) copolymer, and single-walled carbon nanotubes. The MIMBP uses the negative pressure generated by a single button push to collect blood and deliver it to a flexible electrochemical biosensor modified with a gold nanostructure and Pt nanoparticles. We have demonstrated that glucose can be accurately measured up to the molar range in whole human blood collected through the microneedle. The MIMBP platform with HMNs has great potential as a foundation for the future development of simple, wearable, self-testing systems for minimally invasive biomolecule detection. This platform capable of sequential blood collection and high sensitivity glucose detection, which are ideal for personalized and decentralized healthcare.

pH-Stimulated Self-Locked DNA Nanostructure for the Effective Discrimination of Cancer Cells and Simultaneous Detection and Imaging of Endogenous Dual-MicroRNAs

In this study, a pH-stimulated self-locked DNA nanostructure (SLDN) was developed to efficiently distinguish cancer cells from other cells for the simultaneous detection and imaging of endogenous dual-microRNAs (miRNAs). Impressively, the SLDN was specifically unlocked in the acidic environment of cancer cells to form unlocked-SLDN to disengage the i-motif sequence with a labeled fluorophore for the recovery of a fluorescence signal, resulting in the differentiation of cancer cells from normal cells. Meanwhile, unlocked-SLDN could combine and recognize the targets miRNA-21 and miRNA-155 simultaneously to trigger the hybridization chain reaction (HCR) amplification for sensitive dual-miRNA detection, with detection limits of 1.46 pM for miRNA-21 and 0.72 pM for miRNA-155. Significantly, compared with the current miRNA imaging strategy based on the traditional DNA nanostructure, the strategy proposed here remarkably eliminates the interference of normal cells to achieve high-resolution colocation imaging of miRNAs in tumor cells with an ultralow background signal. This work provided a specific differentiation method for tumor cells to materialize sensitive biomarker detection and distinguishable high-definition live-cell imaging for precise cancer diagnosis and multifactor research of tumor progression.

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.

Fluid-based wearable sensors: a turning point in personalized healthcare

Nowadays, it has become very popular to develop wearable devices that can monitor biomarkers to analyze the health status of the human body more comprehensively and accurately. Wearable sensors, specially designed for home care services, show great promise with their ease of use, especially during pandemic periods. Scientists have conducted many innovative studies on new wearable sensors that can noninvasively and simultaneously monitor biochemical indicators in body fluids for disease prediction, diagnosis, and management. Using noninvasive electrochemical sensors, biomarkers can be detected in tears, saliva, perspiration, and skin interstitial fluid (ISF). In this review, biofluids used for noninvasive wearable sensor detection under four main headings, saliva, sweat, tears, and ISF-based wearable sensors, were examined in detail. This report analyzes nearly 50 recent articles from 2017 to 2023. Based on current research, this review also discusses the evolution of wearable sensors, potential implementation challenges, and future prospects.

Advances in dermatological application of GelMA hydrogel microneedles

BACKGROUND

Compared with systemic administration methods like injection and oral administration, traditional transdermal drug delivery has the advantages of rapid onset of activity and low side effects. However, hydrophilic drugs and bioactive substances are often unsuitable for traditional transdermal drug delivery.

METHODS

The application of microneedles made from gelatin methylacryloyl (GelMA) has greatly expanded thepossibilities for skin transdermal drug delivery. We have reviewed the latest literatures about the dermatological application of GelMA hydrogel microneedles in recent years using Google Scholar, PubMed and Springer.

RESULTS

GelMA hydrogel microneedles exhibit huge potency in the diagnosis and treatment of skin diseases, and this technology also brings broad application prospects for subcutaneous micro-invasive transdermal targeted drug delivery, which mainly used in skin tissue fluid collection, local substance delivery and wound healing.

CONCLUSION

With in-depth research on GelMA hydrogel, this technology will bring more breakthroughs and developments in the clinical diagnosis and treatment of skin diseases.

Target-catalyzed self-assembled spherical G-quadruplex/hemin DNAzymes for highly sensitive colorimetric detection of microRNA in serum

The accurate and visual detection of circulating microRNA (miRNA) has attracted increasing interest due to its pivotal role in clinical disease diagnosis. Taking advantages of nucleic acid isothermal amplification and enzyme-catalyzed chromogenic reaction, here, a colorimetric sensing strategy was proposed for sensitive miRNA analysis. When the target miRNA was present, local catalytic hairpin assembly (CHA) would be triggered and proceed continuously to form dozens of double-stranded oligonucleotides with G-rich sticky ends on the gold nanoparticle, which could self-assemble into a spherical G-quadruplex (GQ)/hemin DNAzyme by binding with hemin and potassium ions. As a horseradish peroxidase-mimic, GQ/hemin DNAzyme could catalyze the redox reaction and color change of the substrates. Taking miRNA-21 as an example, the developed method exhibited satisfactory specificity as well as high sensitivity with a detection limit of 90.3 fM. Furthermore, the sensing platform has been successfully employed to detect miRNA-21 in spiked serum, providing a promising tool for early diagnosis of cancers.

Microneedle-based transdermal detection and sensing devices

Microneedles have been expected for the construction of next-generation biosensors towards personalization, digitization, and intellectualization due to their metrics of minimal invasiveness, high integration, and favorable biocompatibility. Herein, an overview of state-of-the-art microneedle-based detection and sensing systems is presented. First, the designs of microneedle devices based on extraction mechanisms are concluded, corresponding to different geometries and materials of microneedles. Second, the targets of equipment-assisted microneedle detections are summarized, as well as the objective significance, revealing the current performance and potential scenarios of these microneedles. Third, the trend towards highly integrated sensors is elaborated by emphasizing the sensing principles (colorimetric, fluorometric and electronic manner). Finally, the key challenges to be tackled and the perspectives on future development are discussed.

Target-mediated self-assembly of DNA networks for sensitive detection and intracellular imaging of APE1 in living cells

Herein, giant DNA networks were assembled from two kinds of functionalized tetrahedral DNA nanostructures (f-TDNs) for sensitive detection and intracellular imaging of apurinic/apyrimidinic endonuclease 1 (APE1) as well as gene therapy in tumor cells. Impressively, the reaction rate of the catalytic hairpin assembly (CHA) reaction on f-TDNs was much faster than that of the conventional free CHA reaction owing to the high local concentration of hairpins, spatial confinement effect and production of giant DNA networks, which significantly enhanced the fluorescence signal to achieve sensitive detection of APE1 with a limit of 3.34 × 10^-8 U μL^-1. More importantly, the aptamer Sgc8 assembled on f-TDNs could enhance the targeting activity of the DNA structure to tumor cells, allowing it to endocytose into cells without any transfection reagents, which could achieve selective imaging of intracellular APE1 in living cells. Meanwhile, the siRNA carried by f-TDN1 could be accurately released to promote tumor cell apoptosis in the presence of endogenous target APE1, realizing effective and precise tumor therapy. Benefiting from the high specificity and sensitivity, the developed DNA nanostructures provide an excellent nanoplatform for precise cancer diagnosis and therapy.

Microneedles as a momentous platform for psoriasis therapy and diagnosis: A state-of-the-art review

Psoriasis is a chronic, autoimmune, and non-communicable skin disease with a worldwide prevalence rate of 2-3%, creating an economic burden on global health. Some significant risk factors associated with psoriasis include genetic predisposition, pathogens, stress, medications, etc. In addition, most patients with psoriasis should also deal with comorbidities such as psoriatic arthritis, inflammatory bowel diseases, cardiovascular diseases, and psychological conditions, including suicidal thoughts. Based on its severity, the treatment approach for psoriasis is categorised into three types, i.e., topical therapy, systemic therapy, and phototherapy. Topical therapy for mild-to-moderate psoriasis faces several issues, such as poor skin permeability, low skin retention of drug formulation, greasy texture of topical vehicle, lack of controlled release, and so on. On the other arrow, systemic therapy via an oral or parenteral route of drug administration involves numerous drawbacks, including first-pass hepatic metabolism, hepatotoxicity, gastrointestinal disturbances, needle pain and phobia, and requirement of healthcare professional to administer the drug. To overcome these limitations, researchers devised a microneedle-based drug delivery system for treating mild-to-moderate and moderate-to-severe psoriasis. A single microneedle system can deliver the anti-psoriatic drugs either locally (topical) or systemically (transdermal) by adjusting the needle height without involving any pain. In this contemplate, the current review provides concise information on the pathophysiology, risk factors, and comorbidities of psoriasis, followed by their current treatment approaches and limitations. Further, it meticulously discusses the potential of microneedles in psoriasis therapy and diagnosis, along with descriptions of their patents and clinical trials.

Microneedle-based interstitial fluid extraction for drug analysis: Advances, challenges, and prospects

Similar to blood, interstitial fluid (ISF) contains exogenous drugs and biomarkers and may therefore substitute blood in drug analysis. However, current ISF extraction techniques require bulky instruments and are both time-consuming and complicated, which has inspired the development of viable alternatives such as those relying on skin or tissue puncturing with microneedles. Currently, microneedles are widely employed for transdermal drug delivery and have been successfully used for ISF extraction by different mechanisms to facilitate subsequent analysis. The integration of microneedles with sensors enables in situ ISF analysis and specific compound monitoring, while the integration of monitoring and delivery functions in wearable devices allows real-time dose modification. Herein, we review the progress in drug analysis based on microneedle-assisted ISF extraction and discuss the related future opportunities and challenges.

Where Microneedle Meets Biomarkers: Futuristic Application for Diagnosing and Monitoring Localized External Organ Diseases

Extracellular tissue fluids are interesting biomatrices that have recently attracted scientists' interest. Many significant biomarkers for localized external organ diseases have been isolated from this biofluid. In the diagnostic and disease monitoring context, measuring biochemical entities from the fluids surrounding the diseased tissues may give more important clinical value than measuring them at a systemic level. Despite all these facts, pushing tissue fluid-based diagnosis and monitoring forward to clinical settings faces one major problem: its accessibility. Most extracellular tissue fluid, such as interstitial fluid (ISF), is abundant but hard to collect, and the currently available technologies are invasive and expensive. This is where novel microneedle technology can help tackle this significant obstacle. The ability of microneedle technology to minimally invasively access tissue fluid-containing biomarkers will enable ISF and other tissue fluid utilization in the clinical diagnosis and monitoring of localized diseases. This review attempts to present the current pursuit of the application of microneedle systems as a diagnostic and monitoring platform, along with the recent progress of biomarker detection in diagnosing and monitoring localized external organ diseases. Then, the potential use of various microneedles in future clinical diagnostics and monitoring of localized diseases is discussed by presenting the currently studied cases.

Skin Interstitial Fluid-Based SERS Tags Labeled Microneedles for Tracking of Peritonitis Progression and Treatment Effect

Skin interstitial fluid (ISF)-based microneedle (MN) sensing has recently exhibited wide promise for the minimally invasive and painless diagnosis of diseases. However, it is still a great challenge to diagnose more disease types due to the limited in situ sensing techniques and insufficient ISF biomarker sources. Herein, ISF is employed to pioneer the tracking of acute peritonitis progression via surface-enhanced Raman scattering (SERS) tags labeled MNs patch technique. Densely deposited core-satellite gold nanoparticles and 3-mercaptophenylboronic acid as a Raman reporter enable the developed MNs patch with high sensitivity and selectivity in the determination of H₂O₂, an indicator of peritonitis development. Importantly, the MNs patch not only reliably tracks the different states of peritonitis but also evaluates the efficacy of drugs in the treatment of peritonitis, as evidenced by the altered SERS signal consistent with plasma pro-inflammatory factor (TNF-α) and peritoneum pathological manifestations. Interestingly, the major source of H₂O₂ in ISF of acute peritonitis investigated may not be through conventional blood capillary filtration pathway. This work provides a new route and technique for the early diagnosis of acute peritonitis and the evaluation of drug therapy effects. The developed MNs patch is promising to serve as a universal sensing tool to greatly enrich the variety and prospect of ISF-based disease diagnosis.

Progress in Gelatin as Biomaterial for Tissue Engineering

Tissue engineering has become a medical alternative in this society with an ever-increasing lifespan. Advances in the areas of technology and biomaterials have facilitated the use of engineered constructs for medical issues. This review discusses on-going concerns and the latest developments in a widely employed biomaterial in the field of tissue engineering: gelatin. Emerging techniques including 3D bioprinting and gelatin functionalization have demonstrated better mimicking of native tissue by reinforcing gelatin-based systems, among others. This breakthrough facilitates, on the one hand, the manufacturing process when it comes to practicality and cost-effectiveness, which plays a key role in the transition towards clinical application. On the other hand, it can be concluded that gelatin could be considered as one of the promising biomaterials in future trends, in which the focus might be on the detection and diagnosis of diseases rather than treatment.