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Ultrasensitive Detection of Biomarkers by Using a Molecular Imprinting Based Capacitive Biosensor
Published on: February 16, 2018
Mercaptophenylboronic acid-modified double-layer PEI-Au magnetic probes: an ultrasensitive SERS biosensor for
Siyun Cheng1, Jin Chen1, Xiaodan Cheng1
1Department of Clinical Laboratory, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing 210008, China.
Abstract:
Accurate identification of uropathogens is critical for guiding effective antibiotic treatment. In this study, we developed a surface-enhanced Raman spectroscopy (SERS) biosensor for rapid and sensitive detection of urinary pathogens. The system combines 4-mercaptophenylboronic acid (MPBA)-modified magnetic gold-shell beads (MSAuS@MPBA) for broad-spectrum bacterial capture with 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB)- and antibody-functionalized gold nanoflowers (AuNFs@Ab) as SERS tags. A double-layer polyethyleneimine (PEI)-assisted 3 nm gold seed design was introduced to fabricate hierarchical rough surfaces on MSAuS@MPBA, significantly enhancing SERS signal generation through localized electromagnetic hotspots. The MSAuS@MPBA achieved capture efficiencies exceeding 87.52% for Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus (S. aureus). Using S. aureus as a model pathogen, the sandwich-type biosensor (MSAuS@MPBA/bacteria/AuNFs@Ab) exhibited a limit of detection (LOD) of 7 CFU mL-1, a wide linear range (101-106 CFU mL-1, R2 = 0.991), excellent specificity against five interfering urinary tract infection (UTI) bacteria, repeatability (RSD < 6.25%), and robust anti-matrix interference in urine and blood. Clinical validation using urine from UTI patients demonstrated high recovery rates (89.11-116.32%), confirming the sensor's practical applicability. This streamlined (∼50 min), ultrasensitive platform provides a clinically translatable method for point-of-care detection of urinary pathogens.
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