A LAMP-based ratiometric electrochemical sensing for ultrasensitive detection of Group B Streptococci with improved stability and accuracy

Abstract

A LAMP ratiometric electrochemical sensor (LAMP E-sensor) for the highly sensitive detection of Group B Streptococci (GBS) was developed based on recycling amplification via LAMP and a dual-signal electrochemical readout. In this LAMP E-sensor, a thiolated β-cyclodextrin (SH-β-CD) was immobilized onto the AuNPs@MoS2-modified electrode surface via Au–S bonding. By using a set of four specially designed primers to amplify the target gene (GBS) in less than 1 h, abundant products modified with ferrocene (Fc) were obtained. These Fc-modified products could connect β-CD via the host–guest interaction between Fc and β-CD. Additionally, methylene blue (MB) was embed in the duplex of the LAMP products, producing a strong electrochemical signal. Using this MB as a reporter and Fc as an internal control, the LAMP E-sensor showed a broad detection range from 1 fg μL−1 to 100 pg μL-1 and a lower detection limit of 0.23 fg μL-1. Moreover, testing data from clinical samples showed a high correlation between the developed LAMP E-sensor and RT-PCR results. In conclusion, with improved sensitivity and good reproducibility, this LAMP E-sensor may be a promising alternative for GBS detection in the field of clinical pathogen-based molecular diagnostics.