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

Abstract

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.

Microneedle‐Mediated Transcutaneous Immunization: Potential in Nucleic Acid Vaccination

“…The ability to extract fluids like interstitial fluid (ISF) and retain them in the gel network makes it possible for swellable MNs to emerge as a minimally invasive tool for disease monitoring and diagnosis, as ISF is a source of various biomarkers. [ 48 ] Moreover, the swelling ratio is determined based on the crosslinking ratio, which is controlled during fabrication. [ 49 ] Compared with the other four types of MNs, there have been relatively fewer studies on using swellable MNs for vaccination.…”

Dermal-fluid-enabled detection platforms for non-invasive ambulatory monitoring

“…Hence, the composition of ISF is very similar to that of blood and reflective of localized physiological information. 10,109 Understanding the role of capillary structure in the partitioning of analytes in ISF from blood is vital to gaining insight into relative concentrations of biomarkers of interest.…”

“…However, it is unsuitable for ambulatory care as the biomarker composition in sampled ISF is often 5–10 times less than the physiological one. 10,32 Extraction of ISF using implantable subcutaneous sensors is widely adopted in CGM systems, but they can be invasive and cause pain, infection, and scarring. 137 The above-mentioned techniques require long sampling times, expert training, healing time for injuries, and local anesthesia.…”

“…9 The most utilized biomarker sources for testing are blood and urine, which are simple to collect for laboratory analysis and can provide a snapshot of systemic biomarker changes. 10 The gold standard for diagnostics is monitoring biomarkers in blood, but the requirement for qualified healthcare workers to draw venous blood or the patient's anxiety during finger-prick blood sampling makes it unsuitable and invasive. Biofluids such as urine, tears, saliva, sweat, and interstitial fluid (ISF) are less invasive alternatives.…”

“…Facile and less invasive ISF sampling techniques employing micro-needle arrays have been attracting interest among researchers in this domain. 10,34…”