Optical-Based Microneedle Arrays for Detection of Cutaneous Melanoma

Abstract

The diagnosis of melanoma cancer is well known to be expensive, uncomfortable, and long. To address this, the following study delved into the development of an optical-based microneedle for the early detection of melanoma cancer. The primary objective was to design a microneedle capable of sampling biomarkers in interstitial fluid. A fluorescent peptide beacon that operated on the principles of FRET was previously designed for the sensing mechanism of the microneedle, in which fluorescence is emitted upon the detection of the target biomarker, S100B. S100B was selected due to its prevalence in interstitial fluid in the presence of growing cancers. The fluorescent peptide beacon design consisted of two coupled arms, where 5-carboxyfluorescein (5-FAM) and dabcyl were used as the donor-accepter system. An ELISA calibration curve was established in the study, and the binding affinity of the beacon to the protein was also tested. The lack of fluorescent signal when testing the binding affinity suggested unsuccessful coupling of the beacon. Poly(L-Lactide) (PLLA) and 20% Polyvinyl Alcohol (PVA) were used to fabricate microneedles. PVA was used as a first approach to create needles for preliminary swelling tests, while the PLLA should be used for more advanced approaches and functionalizing with the beacon. Subsequent swelling tests were carried out on both materials, in which the PVA microneedles dissolved, but the PLLA microneedles demonstrated excellent swelling properties, up to 92% in 120 minutes. Lastly, PVA microneedles were inserted into porcine skin to evaluate their effectiveness in piercing the skin, which they did successfully.