A Carbon‐Dot‐Based Fluorescent Nanosensor for Simple Visualization of Bacterial Nucleic Acids

Abstract

A simple and facile method for sensing of nucleic acids is in great need for disease biomarker detection and diagnosis. Herein, a fluorescent nanosensor utilizing carbon dot nanoparticles is introduced that form visible precipitates in the presence of target DNA. Carbon dot nanoparticles are fabricated by microwave pyrolysis of polyethylenimine, which emits strong photoluminescence and can form precipitates when added to target DNA oligonucleotides. The precipitates can be easily visualized by UV illumination, and data can be acquired as images using a smartphone, which are analyzed for quantification. This carbon-dot-based assay allowed fluorescent sensing of target oligonucleotides with various sizes and visualization even with minimal amount of DNA (≈100 pmol). Finally, the assay can be applied as a nanosensor platform for detecting bacterial DNA for the antibiotic-resistance gene KPC-2 from Klebsiella pneumoniae. This method provides a simple technique for detecting molecular targets, showing wide applicability for diagnostics on the bedside or point-of-care testing.

Expanding the Scope of Nanobiocatalysis and Nanosensing: Applications of Nanomaterial Constructs

“…These nanosensors have been developed to improve detection limits, 106 − 108 allow simultaneous detection of pathogens, 109 differentiate Gram-positive and Gram-negative bacteria, 105 and detect multidrug resistant strains. 110 Recently, nanosensors have been applied in packaging material to respond to environmental conditions during storage and transport to monitor food degradation due to temperature, pH, and moisture changes. Nanosensors are also used to monitor the growth of pathogens, mycotoxins, and some chemicals such as antibiotics that can act as preservatives or antimicrobials to ensure food quality and safety ( Table 2 ).…”

“… Such nanostructures are coupled to antibodies, antimicrobial peptides (AMPs), and nucleic acids to selectively bind with targets. These nanosensors have been developed to improve detection limits, − allow simultaneous detection of pathogens, differentiate Gram-positive and Gram-negative bacteria, and detect multidrug resistant strains . Recently, nanosensors have been applied in packaging material to respond to environmental conditions during storage and transport to monitor food degradation due to temperature, pH, and moisture changes.…”

Carbon-dot-triggered aggregation/dispersion of gold nanoparticles for colorimetric detection of nucleic acids and its application in visualization of loop-mediated isothermal amplification

“…14 Lee et al reported the preparation of CDs from polyethyleneimine and utilized them for the visual detection of bacterial nucleic acids. 15 Although nucleic-acid-specific CDs have been widely used in the fluorometric detection of nucleic acids, they still require the use of a fluorimeter or UV-illumination chamber for signal read-out. Thus, by combining the unique characteristics of CDs with a suitable signal transducer, a straightforward visual colorimetric read-out can be achieved for point-of-care testing applications.…”

Point-of-Care Diagnostics: Molecularly Imprinted Polymers and Nanomaterials for Enhanced Biosensor Selectivity and Transduction

“…POCT aims to bring biomedical diagnostics to all patients that are inexpensive, convenient, and faster than conventionally possible (15)(16)(17)(18). Also, smartphone technology has proven invaluable for connecting relevant stakeholders like patients, physicians, and caregivers in a timely manner (19,20). POCT efforts merged with smartphone advances allow for biosensors connected to the internet, contributing to timely, equitable, and affordable access to quality healthcare.…”