Lab-on-a-Molecule Probe: Multitarget Detection of Five Aromatic Pesticides Using a Supramolecular Probe under Single Wavelength Excitation

In order to prevent and control the effects of pesticide residues on human health and the ecological environment, the rapid, highly sensitive, and selective detection of multiple pesticide residues has become an urgent problem to be solved. Herein, a lab-on-a-molecule probe based on a host-guest complex (ThT@Q[8] probe) has been developed to simultaneously analyze multiple aromatic pesticides under single wavelength excitation, such as fuberidazole, thiabendazole, carbendazim, thidiazuron, and tricyclazole. The fluorescence titration spectra of the ThT@Q[8] probe with the five pesticides mentioned above showed that the fluorescence intensity exhibited a good linear correlation with the pesticide concentration and the limit of detection was as low as 10^-7 M. Because the ThT@Q[8] probe exhibits diverse fluorescence color changes to the five pesticides studied under a 365 nm ultraviolet lamp, we fabricated a single probe used to detect multiple analytes in the RGB triple channel by extracting the RGB variations. Principal component analysis and linear discriminant analysis proved that the ThT@Q[8] probe can recognize and distinguish five pesticides and can be applied at different concentrations. In real samples, the ThT@Q[8] probe recognized and distinguished five pesticides in tap water and Huaxi River water. The ¹H NMR spectra results proved that a charge-transfer complex of ThT and pesticides in the Q[8] cavity may be formed. Moreover, we selected a test strip as a carrier to detect pesticides. The results indicate it can be used to quickly and conveniently detect different pesticides due to the rapid color change. Besides, the ThT@Q[8] probe has good cell permeability and can be used to detect pesticide residues in living cells. This work has laid the foundation for the qualitative and quantitative multitarget detection of pesticide residues.

Rapid Visual Screening and Programmable Subtype Classification of Ebola Virus Biomarkers

The massive outbreaks of the highly transmissible and lethal Ebola virus disease were caused by infection with one of the Ebolavirus species. It is vital to develop cost-effective, highly sensitive and selective multitarget biosensing platforms that allow for both the detection and phenotyping. Here, a highly programmable, cost-efficient and multianalyte sensing approach is reported that enables visual detection and differentiation of conserved oligonucleotide regions of all Ebolavirus subtypes known to infect human primates. This approach enables the detection of as little as 400 amols (24 × 10⁶ molecules) of target sequences with the naked eye. Furthermore, the detection assay can be used to classify four virus biomarkers using a single nanoprobe template. This can be achieved by using different combinations of short single stranded initiator molecules, referred to as programming units, which also enable the simultaneous and rapid identification of the four biomarkers in 16 different combinations. The results of 16 × 5 array studies illustrate that the system is extremely selective with no false-positive or false-negative. Finally, the target strands in liquid biopsy mimics prepared from urine specimens are also able to be identified and classified.