Microneedle Array Technique for the Longitudinal Extraction of Interstitial Fluid without Hair Removal

Area of Science:

• Biomedical Engineering
• Translational Medicine
• Analytical Chemistry

Background:

• Interstitial fluid (ISF) is a rich source of biomolecules for diagnostic and research purposes.
• Existing ISF extraction methods often require specialized animal models or are invasive.
• A minimally invasive, cost-effective in vivo ISF extraction technique is needed for pre-clinical studies.

Purpose of the Study:

• To demonstrate the applicability of a 3D-printed microneedle array (MA) for in vivo interstitial fluid (ISF) extraction in Sprague Dawley rats.
• To validate the technique for multiple extractions over an extended period without hair removal.
• To showcase the utility of MA-extracted ISF for quantifying heavy metals.

Main Methods:

• Development and application of a 3D-printed microneedle array (MA) platform for ISF extraction.
• In vivo experiments conducted on Sprague Dawley rats, without requiring hair removal.
• Multiple ISF sampling sessions performed over several weeks.
• Simultaneous quantification of heavy metals (Copper, Lead, Lithium, Nickel) in ISF and whole blood using inductively coupled plasma mass spectrometry (ICP-MS).

Main Results:

• Successful in vivo ISF extraction using the MA platform in Sprague Dawley rats without hair removal.
• Demonstrated feasibility of repeated ISF sampling from the same animals over multiple weeks.
• Quantified heavy metals (Cu, Pb, Li, Ni) in ISF, showing comparable or differential levels to whole blood.
• Validated the MA technique for broader species applicability and reduced animal usage.

Conclusions:

• The 3D-printed MA platform offers a versatile, minimally invasive, and efficient method for in vivo ISF extraction.
• This technique supports longitudinal studies and reduces the number of animals required for research.
• MA-based ISF analysis is valuable for monitoring biomarkers, including heavy metals, in pre-clinical settings.