Protection of Nanostructures-Integrated Microneedle Biosensor Using Dissolvable Polymer Coating

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Biosensing

Background:

• Real-time transdermal biosensing enables local tissue biomarker quantification.
• Integrating nanostructures with microneedles (MNs) for enhanced sensing is challenging due to mechanical damage during skin insertion.
• Nanostructures on MNs are vulnerable to destruction from friction.

Purpose of the Study:

• To develop a protective coating for nanostructure-integrated MNs to prevent mechanical damage during skin insertion.
• To demonstrate the efficacy of a dissolvable polymer coating in preserving nanostructure functionality for transdermal biosensing.
• To enable minimally invasive quantification of biomarkers in skin tissue.

Main Methods:

• A dissolvable poly(vinyl pyrrolidone) polymer coating was spray-coated onto microneedles (MNs) functionalized with vertical zinc oxide nanowires (vNWs).
• The coated MNs were inserted into skin tissue (ex vivo and in vivo) to assess the protective effect of the polymer layer.
• Transdermal biosensing of hydrogen peroxide (H2O2) was performed using both coated and uncoated vNW-MNs.

Main Results:

• The dissolvable polymer coating effectively protected the ZnO nanowires on the MNs during skin penetration.
• Re-exposure of nanostructures occurred upon polymer dissolution by interstitial fluid.
• The polymer-protected MN sensor maintained its sensing functionality, while uncoated MNs showed a 3-fold decrease in sensitivity.

Conclusions:

• A dissolvable polymer coating technique successfully protects nanostructure-integrated MNs from mechanical damage during transdermal insertion.
• This method preserves the sensing capabilities of nanomodified MNs for effective minimally invasive biosensing.
• The approach offers new possibilities for advanced transdermal biosensing applications.