An integrated and portable optoelectronic biosensing system for rapid post-extraction on-site quantification of Heterosigma akashiwo.

Authors

Le Qiang, Shicai Xu, Jun Sun, Lin Han, Yu Zhang

Published in

Mikrochimica acta. Volume 193. Issue 8. Jul 28, 2026. Epub Jul 28, 2026.

Abstract

Rapid, species-level identification of harmful algal blooms (HAB) remains constrained by laboratory-based molecular workflows and bulky fluorescence instrumentation. We report an integrated portable optoelectronic biosensing system for post-extraction quantification of Heterosigma akashiwo 18S rDNA. The key innovation is not the GO-based recognition chemistry itself, but the analytical signal-reading and conversion strategy: GO-regulated fluorescence recovery is captured by a sealed lens-filter-PIN photodiode module and converted through a resistor-based current-to-voltage circuit into an amplified photovoltage output. FITC-labelled ssDNA probes are quenched by GO nanosheets and recover fluorescence upon target hybridization. The recovered fluorescence is excited by a fixed-wavelength 488 nm laser, filtered at 520 ± 10 nm, collected by a sealed optical detection head, converted from photocurrent to photovoltage across a 10 kΩ sense resistor, amplified 500-fold, and digitized for quantitative readout. This voltage-mode architecture eliminates reliance on benchtop fluorimeters, microscope-camera assemblies, or picoampere-level current instrumentation, thereby improving the portability and practical usability of GO-based fluorescence assays. Using a 12-well double-layer microfluidic cartridge and a modified Stern-Volmer linearization strategy, the system quantified target DNA over 10^- 4-10⁵ pM with a limit of detection of 79.90 aM. After extracted DNA was introduced into the cartridge, the assay delivered results within 30 min. Specificity was verified using one- and two-base mismatch sequences and non-complementary DNA from co-occurring HAB species. Mixed-sample tests at both gene and cell levels further demonstrated sequence-specific quantification. This work advances GO-regulated fluorescence HAB sensing toward a portable post-extraction voltage-output platform for rapid microalgal monitoring.

PMID:
42517930
Bibliographic data and abstract were imported from PubMed on 28 Jul 2026.

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