Biosensor Based on pSi-SU-8-GQD Heterostructures for Enhanced Viral Detection by Dual Signal Amplification Strategy

DNA microarray technology requires optimizing substrate properties and DNA labeling strategies for enhanced detection. This study introduces an improved biosensor platform utilizing nanoporous silicon (pSi) substrates with a glycidyl ether of bisphenol A (SU-8) polymer coating, decorated with graphene quantum dots (GQDs), to amplify fluorescent signals. We compared two methods for obtaining labeled single-stranded DNA: Lambda exonuclease digestion of phosphorylated PCR products and asymmetric PCR (aPCR) with Cy5-labeled nested primers. Our findings demonstrate that pSi biochips with 7 nm pores covered by thicker SU-8 layers (700-750 nm) provide 52% higher signal relative to the standard deviation. The aPCR labeling method demonstrated superior performance, yielding significantly stronger signals -4.06 mean signal intensity and a standard deviation of 0.16. Decorating the SU-8 coating with 6 nm GQDs further amplified the signal intensity by 11%. These findings highlight the need to optimize DNA labeling and utilize nanostructured heterostructures for enhanced microarray performance, with implications for personalized medicine and diagnostics.