ABSTRACT
BACKGROUND: Needle-free jet injection (NFJI) systems enable a controlled and targeted delivery of drugs into skin tissue. However, a scarce understanding of their underlying mechanisms has been a major deterrent to the development of an efficient system. Primarily, the lack of a suitable visualization technique that could capture the dynamics of the injected fluid-tissue interaction with a microsecond range temporal resolution has emerged as a main limitation. A conventional needle-free injection system may inject the fluids within a few milliseconds and may need a temporal resolution in the microsecond range for obtaining the required images. However, the presently available imaging techniques for skin tissue visualization fail to achieve these required spatial and temporal resolutions. Previous studies on injected fluid-tissue interaction dynamics were conducted using in vitro media with a stiffness similar to that of skin tissue. However, these media are poor substitutes for real skin tissue, and the need for an imaging technique having ex vivo or in vivo imaging capability has been echoed in the previous reports. METHODS: A near-infrared imaging technique that utilizes the optical absorption and fluorescence emission of indocyanine green dye, coupled with a tissue clearing technique, was developed for visualizing a NFJI in an ex vivo porcine skin tissue. RESULTS: The optimal imaging conditions obtained by considering the optical properties of the developed system and mechanical properties of the cleared ex vivo samples are presented. Crucial information on the dynamic interaction of the injected liquid jet with the ex vivo skin tissue layers and their interfaces could be obtained. CONCLUSIONS: The reported technique can be instrumental for understanding the injection mechanism and for the development of an efficient transdermal NFJI system as well.
ABSTRACT
This paper promotes a basic, quick, stature adaptable, and direct approach to selecting exceptionally suitable materials in polyethylene glycol diacrylate (PEGDA) and silicon for microneedle fabrication. Researchers and scientists are facing challenges in readily selecting biocompatible materials for microneedle fabrication. Solid porous silicon and PEGDA microneedles are particularly biocompatible and desirable for vaccine delivery by the transdermal vaccine delivery method if microneedle arrays are fabricated successfully using lithography techniques as they belong to enhanced patient concurrence and well-being. Moreover, silicon and PEGDA microneedles are the ultimate for conveying coronavirus vaccines. In this work, we applied the ANSYS workbench tool to investigate the properties of triangular pyramidal-shaped solid silicon and PEGDA microneedle array to perform structural analysis on microneedle for estimating the capability of an array of needles to enter and convey vaccines along with the skin. These outcomes demonstrated that microneedles of porous silicon are better than polymers such as PEGDA as far as mechanical strength and capacity to convey drugs. Buckling was anticipated as the fundamental method to estimate the failure of microneedles and finally, by analysis, it was clear that buckling does not impact the potential of the silicon microneedle needle array. Silicon and PEGDA microneedles are penetrated against human skin surfaces in explicit dynamics by utilizing the ANSYS tool to select the best material. Along these lines, the current strategy can work with silicon and PEGDA microneedles for useful applications. The von Mises stresses generated by applying loads on silicon and PEGDA arrays were greater than the skin resistance of 3.18 MPa and suitable for skin insertion. Silicon microneedles are sustained due to buckling but PEGDA needles fail if the loading is more than 0.1 N. Vaccination can be provided to humans if needle arrays are fabricated based on this approach and design analysis and considering parameters.
ABSTRACT
The recent advancement and prevalence of wearable technologies and their ability to make digital measurements of vital signs and wellness parameters have triggered a new paradigm in the management of diseases. Drug delivery as a function of stimuli or response from wearable, closed-loop systems can offer real-time on-demand or preprogrammed drug delivery capability and offer total management of disease states. Here we review the key opportunities in this space for development of closed-loop systems, given the advent of digital wearable technologies. Particular considerations and focus are given to closed-loop systems combined with transdermal drug delivery technologies.
Subject(s)
Administration, Cutaneous , Drug Delivery Systems , Wearable Electronic Devices/trends , Animals , Equipment Design , Humans , SkinABSTRACT
Transdermal drug delivery systems (TDDS) have many advantages and represent an excellent alternative to oral delivery and hypodermic injections. TDDS are more convenient and less invasive tools for disease and viral infection treatment, prevention, detection, and surveillance. The emerging development of microneedles for TDDS has facilitated improved skin barrier penetration for the delivery of macromolecules or hydrophilic drugs. Microneedle TDDS patches can be fabricated to deliver virus vaccines and potentially provide a viable alternative vaccine modality that offers improved immunogenicity, thermostability, simplicity, safety, and compliance as well as sharp-waste reduction, increased cost-effectiveness, and the capacity for self-administration, which could improve vaccine distribution. These advantages make TDDS-based vaccine delivery an especially well-suited option for treatment of widespread viral infectious diseases including pandemics. Because microneedle-based bioassays employ transdermal extraction of interstitial fluid or blood, they can be used as a minimally invasive approach for surveying disease markers and providing point-of-care (POC) diagnostics. For cutaneous viral infections, TDDS can provide localized treatment with high specificity and less systemic toxicity. In summary, TDDS, especially those that employ microneedles, possess special attributes that can be leveraged to reduce morbidity and mortality from viral infectious diseases. In this regard, they may have considerable positive impact as a modality for improving global health. In this article, we introduce the possible role and summarize the current literature regarding TDDS applications for fighting common cutaneous or systemic viral infectious diseases, including herpes simplex, varicella or herpes zoster, warts, influenza, measles, and COVID-19.