Smart Responsive Microarray Patches for Transdermal Drug Delivery and Biological Monitoring

Theory of nanostructured sensors integrated in/on microneedles for diagnostics and therapy

Efficient real-time diagnostics and on-demand drug delivery are essential components in modern healthcare, especially for managing chronic diseases. The lack of a rapid and effective sensing and therapeutic system can result in analyte level deviations, leading to severe complications. Minimally invasive microneedle (MN)-based patches integrating nanostructures (NSs) in their volume or on their surface have emerged as a biocompatible technology for delay-free analyte sensing and therapy. However, a quantitative relationship for the signal response in NS-assisted reactions remains elusive. Existing generalized formalisms are derived for in-vitro applications, raising questions about their direct applicability to in-situ wearable sensors. In this study, we apply the reaction-diffusion theory to establish a generalized physics-guided framework for NS-in-MN platforms in wearable applications. The model relates the signal response to analyte concentration, incorporating geometric, physical, and catalytic platform properties. Approximating the model under NS (binding or catalytic) and environmental (mass transport) limitations, we validate it against numerical simulations and various experimental results from diverse conditions - analyte sensing (glucose, lactic acid, pyocyanin, miRNA, etc.) in artificial and in-vivo environments (humans, mice, pigs, plants, etc.) through electrochemical and optical/colorimetric, enzymatic and non-enzymatic platforms. The results plotted in the scaled response show that (a) NS-limited platforms exhibit a linear dependence, (b) Mass transport-limited platforms saturate to 1, (c) a one-to-one mapping against traditional sensitivity plots unifies the scattered data points reported in literature. The universality of the model provides insightful perspectives for the design and optimization of MN-based sensing technologies, with potential extensions to dissolvable MNs as part of analyte-responsive closed-loop therapeutic applications.

Functional biomacromolecules-based microneedle patch for the treatment of diabetic wound

Diabetic wounds are a common complication of diabetes. The prolonged exposure to high glucose and oxidative stress in the wound environment increases the risk of bacterial infection and abnormal angiogenesis, leading to amputation. Microneedle patches have shown promise in promoting the healing of diabetic wounds through transdermal drug delivery. These patches target the four main aspects of diabetic wound treatment: hypoglycemia, antibacterial action, inflammatory regulation, and tissue regeneration. By overcoming the limitations of traditional administration methods, microneedle patches enable targeted therapy for deteriorated tissues. The design of these patches extends beyond the selection of needle tip material and biomacromolecule encapsulated drugs; it can also incorporate near-infrared rays to facilitate cascade reactions and treat diabetic wounds. In this review, we comprehensively summarize the advantages of microneedle patches compared to traditional treatment methods. We focus on the design and mechanism of these patches based on existing experimental articles in the field and discuss the potential for future research on microneedle patches.

Current approaches in smart nano-inspired drug delivery: A narrative review

Background and Aim

The traditional drug delivery approach involves systemic administration of a drug that could be nonspecific in targeting, low on efficacy, and with severe side-effects. To address such challenges, the field of smart drug delivery has emerged aiming at designing and developing delivery systems that can target specific cells, tissues, and organs and have minimal off-target side-effects.

Methods

A literature search was done to collate papers and reports about the currently available various strategies for smart nano-inspired drug delivery. The databases searched were PubMed, Scopus, and Google Scholar. Based on selection criteria, the most pertinent and recent items were included.

Results

Smart drug delivery is a cutting-edge revolutionary intervention in modern medicines to ensure effective and safe administration of therapeutics to target sites. These hold great promise for targeted and controlled delivery of therapeutic agents to improve the efficacy with reduced side-effects as compared to the conventional drug delivery approaches. Current smart drug delivery approaches include nanoparticles, liposomes, micelles, and hydrogels, each with its own advantages and limitations. The success of these delivery systems lies in engineering and designing them, and optimizing their pharmacokinetics and pharmacodynamics properties.

Conclusion

Development of drug delivery systems that can get beyond various physiological and clinical barriers, as observed in conventionally administered chemotherapeutics, has been possible through recent advancements. Using multifunctional targeting methodologies, smart drug delivery tries to localize therapy to the target location, reduces cytotoxicity, and improves the therapeutic index. Rapid advancements in research and development in smart drug delivery provide wider and more promising avenues to guarantee a better healthcare system, improve patient outcomes, and achieve higher levels of effective medical interventions like personalized medicine.

Nanomaterial-based Electrochemical Sensors for Multiplex Medicinal Applications

This review explores the advancements in nanomaterial-based electrochemical sensors for the multiplex detection of medicinal compounds. The growing demand for efficient and selective detection methods in the pharmaceutical field has prompted significant research into the development of electrochemical sensors employing nanomaterials. These materials, defined as functional materials with at least one dimension between 1 and 100 nanometers, encompass metal nanoparticles, polymers, carbon-based nanocomposites, and nano-bioprobes. These sensors are characterized by their enhanced sensitivity and selectivity, playing a crucial role in simultaneous detection and offering a comprehensive analysis of multiple medicinal complexes within a single sample. The review comprehensively examines the design, fabrication, and application of nanomaterial- based electrochemical sensors, focusing on their ability to achieve multiplex detection of various medicinal substances. Insights into the strategies and nanomaterials employed for enhancing sensor performance are discussed. Additionally, the review explores the challenges and future perspectives of this evolving field, highlighting the potential impact of nanomaterial-based electrochemical sensors on the advancement of medicinal detection technologies.

Recent advances in bacterial cellulose-based antibacterial composites for infected wound therapy

Wound infection arising from pathogenic bacteria brought serious trouble to the patient and medical system. Among various wound dressings that are effective in killing pathogenic bacteria, antimicrobial composites based on bacterial cellulose (BC) are becoming the most popular materials due to their success in eliminating pathogenic bacteria, preventing wound infection, and promoting wound healing. However, as an extracellular natural polymer, BC is not inherently antimicrobial, which means that it must be combined with other antimicrobials to be effective against pathogens. BC has many advantages over other polymers, including nano-structure, significant moisture retention, non-adhesion to the wound surface, which has made it superior to other biopolymers. This review introduces the recent advances in BC-based composites for the treatment of wound infection, including the classification and preparation methods of composites, the mechanism of wound treatment, and commercial application. Moreover, their wound therapy applications include hydrogel dressing, surgical sutures, wound healing bandages, and patches are summarized in detail. Finally, the challenges and future prospects of BC-based antibacterial composites for the treatment of infected wounds are discussed.

Effect of natural polymer materials on skin healing based on internal wound microenvironment: a review

The concept of wound microenvironment has been discussed for a long time. However, the mechanism of the internal microenvironment is relatively little studied. Here, we present a systematic discussion on the mechanism of natural polymer materials such as chitosan, cellulose, collagen and hyaluronic acid through their effects on the internal wound microenvironment and regulation of wound healing, in order to more comprehensively explain the concept of wound microenvironment and provide a reference for further innovative clinical for the preparation and application of wound healing agents.

Bibliometric analysis and visualization of transdermal drug delivery research in the last decade: global research trends and hotspots

Background: Transdermal delivery has become a crucial field in pharmaceutical research. There has been a proliferation of innovative methods for transdermal drug delivery. In recent years, the number of publications regarding transdermal drug delivery has been rising rapidly. To investigate the current research trends and hotspots in transdermal drug delivery, a comprehensive bibliometric analysis was performed. Methods: An extensive literature review was conducted to gather information on transdermal drug delivery that had been published between 2003 and 2022. The articles were obtained from the Web of Science (WOS) and the National Center for Biotechnology Information (NCBI) databases. Subsequently, the collected data underwent analysis and visualization using a variety of software tools. This approach enables a deeper exploration of the hotspots and emerging trends within this particular research domain. Results: The results showed that the number of articles published on transdermal delivery has increased steadily over the years, with a total of 2,555 articles being analyzed. The most frequently cited articles were related to the optimization of drug delivery and the use of nanotechnology in transdermal drug delivery. The most active countries in the field of transdermal delivery research were the China, United States, and India. Furthermore, the hotspots over the past 2 decades were identified (e.g., drug therapy, drug delivery, and pharmaceutical preparations and drug design). The shift in research focus reflects an increasing emphasis on drug delivery and control release, rather than simply absorption and penetration, and suggests a growing interest in engineering approaches to transdermal drug delivery. Conclusion: This study provided a comprehensive overview of transdermal delivery research. The research indicated that transdermal delivery would be a rapidly evolving field with many opportunities for future research and development. Moreover, this bibliometric analysis will help researchers gain insights into transdermal drug delivery research's hotspots and trends accurately and quickly.

Electro-responsive silk fibroin microneedles for controlled release of insulin

To date, very limited work has been done on convenient and active control of insulin release. Herein, we report an electro-responsive insulin delivery system based on thiolated silk fibroin. The disulfide cross-linking points in TSF were reduced and broken to form sulfhydryl groups under electrification, which led to the increase of microneedle swelling degree and promoted insulin release. After power failure, the sulfhydryl group is oxidised to form disulfide bond crosslinking point again, resulting in the reduction of microneedle swelling degree and thus the reduction of release rate. The insulin loaded in the electro-responsive insulin delivery system showed good reversible electroresponsive release performance. The addition of graphene reduced the microneedle resistance and increased the drug release rate under current conditions. In vivo studies on type 1 diabetic mice show that electro-responsive insulin delivery system effectively controls the blood glucose before and after feeding by switching on and off the power supply, and this blood glucose control can be maintained within the safe range (100-200 mg/dL) for a long time (11h). Such electrically responsive delivery microneedles show potential for integration with glucose signal monitoring and are expected to build closed-loop insulin delivery systems.

Microneedle Patch Loaded with Exosomes Containing MicroRNA-29b Prevents Cardiac Fibrosis after Myocardial Infarction

Myocardial infarction (MI) is a cardiovascular disease that poses a serious threat to human health. Uncontrolled and excessive cardiac fibrosis after MI has been recognized as a primary contributor to mortality by heart failure. Thus, prevention of fibrosis or alleviation of fibrosis progression is important for cardiac repair. To this end, a biocompatible microneedle (MN) patch based on gelatin is fabricated to load exosomes containing microRNA-29b (miR-29b) mimics with antifibrotic activity to prevent excessive cardiac fibrosis after MI. Exosomes are isolated from human umbilical cord mesenchymal stem cells and loaded with miR-29b mimics via electroporation, which can be internalized effectively in cardiac fibroblasts to upregulate the expression of miR-29b and downregulate the expression of fibrosis-related proteins. After being implanted in the infarcted heart of a mouse MI model, the MN patch can increase the retention of loaded exosomes in the infarcted myocardium, leading to alleviation of inflammation, reduction of the infarct size, inhibition of fibrosis, and improvement of cardiac function. This design explored the MN patch as a suitable platform to deliver exosomes containing antifibrotic biomolecules locally for the prevention of cardiac fibrosis, showing the potential for MI treatment in clinical applications.

Minimally invasive electrochemical continuous glucose monitoring sensors: Recent progress and perspective

Diabetes and its complications are seriously threatening the health and well-being of hundreds of millions of people. Glucose levels are essential indicators of the health conditions of diabetics. Over the past decade, concerted efforts in various fields have led to significant advances in glucose monitoring technology. In particular, the rapid development of continuous glucose monitoring (CGM) based on electrochemical sensing principles has great potential to overcome the limitations of self-monitoring blood glucose (SMBG) in continuously tracking glucose trends, evaluating diabetes treatment options, and improving the quality of life of diabetics. However, the applications of minimally invasive electrochemical CGM sensors are still limited owing to the following aspects: i) invasiveness, ii) short lifespan, iii) biocompatibility, and iv) calibration and prediction. In recent years, the performance of minimally invasive electrochemical CGM systems (CGMSs) has been significantly improved owing to breakthrough developments in new materials and key technologies. In this review, we summarize the history of commercial CGMSs, the development of sensing principles, and the research progress of minimally invasive electrochemical CGM sensors in reducing the invasiveness of implanted probes, maintaining enzyme activity, and improving the biocompatibility of the sensor interface. In addition, this review also introduces calibration algorithms and prediction algorithms applied to CGMSs and describes the application of machine learning algorithms for glucose prediction.

A 3D-printed transepidermal microprojection array for human skin microbiome sampling

Skin microbiome sampling is currently performed with tools such as swabs and tape strips to collect microbes from the skin surface. However, these conventional approaches may be unable to detect microbes deeper in the epidermis or in epidermal invaginations. We describe a sampling tool with a depth component, a transepidermal microprojection array (MPA), which captures microbial biomass from both the epidermal surface and deeper skin layers. We leveraged the rapid customizability of 3D printing to enable systematic optimization of MPA for human skin sampling. Evaluation of sampling efficacy on human scalp revealed the optimized MPA was comparable in sensitivity to swab and superior to tape strip, especially for nonstandard skin surfaces. We observed differences in species diversity, with the MPA detecting clinically relevant fungi more often than other approaches. This work delivers a tool in the complex field of skin microbiome sampling to potentially address gaps in our understanding of its role in health and disease.

Dissolvable polymer microneedles for drug delivery and diagnostics

Dissolvable transdermal microneedles (μND) are promising micro-devices used to transport a wide selection of active compounds into the skin. To provide an effective therapeutic outcome, μNDs must pierce the human stratum corneum (~10 to 20 μm), without rupturing or bending during penetration, then release their cargo at the predetermined area and time. The ability of dissolvable μND arrays/patches to sufficiently pierce the skin is a crucial requirement, which depends on the material composition, μND geometry and fabrication techniques. This comprehensive review not only provides contemporary knowledge on the μND design approaches, but also the materials science facilitating these delivery systems and the opportunities these advanced materials can provide to enhance clinical outcomes.

Wearable hollow microneedle sensing patches for the transdermal electrochemical monitoring of glucose

According to the World Health Organization, about 422 million people worldwide have diabetes, with 1.5 million deaths directly attributed each year. Therefore, there is still a need to effectively monitor glucose in diabetic patients for proper management. Recently, wearable patches based on microneedle (MN) sensors provide minimally invasive analysis of glucose through the interstitial fluid (ISF) while exhibiting excellent correlation with blood glucose. Despite many advances in wearable electrochemical sensors, long-term stability and continuous monitoring remain unsolved challenges. Herein, we present a highly stable electrochemical biosensor based on a redox mediator bilayer consisting of Prussian blue and iron-nickel hexacyanoferrate to increase the long-term stability of the readout coupled with a hollow MN array as a sampling unit for ISF uptake. First, the enzymatic biosensor is developed by using affordable screen-printed electrodes (SPE) and optimized for long-term stability fitting the physiological range of glucose in ISF (i.e., 2.5-22.5 mM). In parallel, the MN array is assessed for minimally invasive piercing of the skin. Subsequently, the biosensor is integrated with the MN array leaving a microfluidic spacer that works as the electrochemical cell. Interestingly, a microfluidic channel connects the cell with an external syringe to actively and rapidly withdraw ISF toward the cell. Finally, the robust MN sensing patch is characterized during in vitro and ex vivo tests. Overall, affordable wearable MN-based patches for the continuous monitoring of glucose in ISF are providing an advent in wearable devices for rapid and life-threatening decision-making processes.

Stimuli-Responsive Microneedles as a Transdermal Drug Delivery System: A Demand-Supply Strategy

Microneedles are one of the most prominent approaches capable of physically disrupting the stratum corneum without devastating the deeper tissues to deliver both small molecules and macromolecules into the viable epidermis/dermis for local/systemic effects. Over the past two decades, microneedles have caught the attention of many researchers because of their outstanding advantages over oral and parenteral drug delivery systems such as self-administration, pain-free, steady-plasma concentration maintenance, avoidance of first-pass hepatic biotransformation, and so on. So far, scientists have reported various types of microneedle patches to deliver the loaded therapeutics as soon as the microneedles are inserted into the skin, regardless of the demand for therapeutics to treat a specific condition. This way of drug delivery can lead to potential risks such as poor therapeutic efficacy or drug overdose. The stimuli-responsive microneedles are the most predominant tool to achieve the on-demand/need-based drug delivery, leading to safe and effective treatment. Various natural and synthetic polymers that can undergo significant transitions such as swelling, shrinking, dissolution, or disintegration play a pivotal role in the development of stimuli-responsive microneedles. The current Review provides brief information about the history, emergence, type, and working principles of microneedles. Furthermore, it selectively discusses various exogenous and endogenous stimuli-responsive microneedles along with their mechanism of action involved in treating different disease conditions. Collaterally, the emergence of "closed-loop" combinatorial stimuli-responsive microneedle patches for precise delivery of therapeutics is meticulously canvassed. Subsequently, it covers the patents of different stimuli-responsive microneedles and further highlights the existing challenges and future perspectives concerning clinical application and large-scale production.

Optogenetic approaches in biotechnology and biomaterials

Advances in genetic engineering, combined with the development of optical technologies, have allowed optogenetics to broaden its area of possible applications in recent years. However, the application of optogenetic tools in industry, including biotechnology and the production of biomaterials, is still limited, because each practical task requires the engineering of a specific optogenetic system. In this review, we discuss recent advances in the use of optogenetic tools in the production of biofuels and valuable chemicals, the synthesis of biomedical and polymer materials, and plant agrobiology. We also offer a comprehensive analysis of the properties and industrial applicability of light-controlled and other smart biomaterials. These data allow us to outline the prospects for the future use of optogenetics in bioindustry.