Aptamer conjugated indium phosphide quantum dots with a zinc sulphide shell as photoluminescent labels for acinetobacter baumannii

<i>Acinetobacter baumannii</i> is a remarkable microorganism known for its diversity of habitat and its multi-drug resistance, resulting in hard-to-treat infections. Thus, a sensitive method for the identification and detection of <i>Acinetobacter baumannii</i> is vital. However, current methods used for the detection of pathogens have not improved in the past decades and suffer from long process times and low detection limits. A cheap, quick, and easy detection mechanism is needed. In this work, we successfully prepared indium phosphide quantum dots with a zinc sulphide shell, conjugated to a targeting aptamer ligand, to specifically label <i>Acinetobacter baumannii</i>. The system retained both the photophysical properties of the quantum dots and the folded structure and molecular recognition function of the aptamer, therefore successfully targeting <i>Acinetobacter baumannii</i>. Confocal microscopy and transmission electron microscopy showed the fluorescent quantum dots surrounding the <i>Acinetobacter baumannii</i> cells confirming the specificity of the aptamer conjugated to indium phosphide quantum dots with a zinc sulphide shell. Controls were undertaken with a different bacteria species, showing no binding of the aptamer conjugated quantum dots. Our strategy offers a novel method to detect bacteria and engineer a scalable platform for fluorescence detection, therefore improving current methods and allowing for better treatment.