We report the electrochemical detection of the redox active cardiac biomarker myoglobin (Mb) using aptamer-functionalized black phosphorus nanostructured electrodes by measuring direct electron transfer. The as-synthesized few-layer black phosphorus nanosheets have been functionalized with poly-l-lysine (PLL) to facilitate binding with generated anti-Mb DNA aptamers on nanostructured electrodes. This aptasensor platform has a record-low detection limit (∼0.524 pg mL(-1)) and sensitivity (36 μA pg(-1) mL cm(-2)) toward Mb with a dynamic response range from 1 pg mL(-1) to 16 μg mL(-1) for Mb in serum samples. This strategy opens up avenues to bedside technologies for multiplexed diagnosis of cardiovascular diseases in complex human samples.

The stability of few-layer black phosphorus has been studied in aqueous media using a range of spectroscopic techniques. The material is meta-stable, degrading over time mainly to phosphoric acids.

A nanohybrid mediated SERS substrate was prepared by in-situ synthesis and assembly of gold nanoparticles (AuNPs) on exfoliated nanosheets of tungsten disulfide (WS) to form plasmonic hotspots. The nanohybrid surface was functionalized with specific aptamers which imparted high selectivity for the cardiac marker myoglobin (Mb). The fabricated aptasensor was read by SERS using a 532 nm laser and demonstrated significant signal enhancement, and this allowed Mb to be determined in the 10 f. mL to 0.1 μg mL concentration range. The study presents an approach to synergistically exploit the unique chemical and electromagnetic properties of both WS and AuNPs for many-fold enhancement of SERS signals. Graphical abstract Schematic presentation of a nanohybrid-mediated SERS substrate prepared by in-situ assembly of gold nanoparticles (AuNPs) reduced on exfoliated nanosheets of tungsten disulfide (WS) to form plasmonic hot spots. Specific aptamers immobilized on the SERS surface impart high sensitivity and selectivity for the cardiac marker myoglobin (Mb).

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Combining synthetic macromolecules and biomolecular recognition units are promising in developing novel diagnostic and analysis techniques for detecting environmental and/or clinically important substances. Fluorescence resonance energy transfer (FRET) apta-immunosensor for explosive detection is reported using 2,4,6-trinitrotoluene (TNT) specific aptamer and antibodies tagged with respective FRET pair dyes in a sandwich immunoassay format. FITC-labeled aptamer was used as a binder molecule in the newly developed apta-immunoassay format where the recognition element was specific anti-TNT antibody labeled with rhodamine isothiocyanate. The newly developed sensing platform showed excellent sensitivity with a detection limit of the order of 0.4 nM presenting a promising candidate for routine screening of TNT in samples.

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