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Single-molecule detection of protein efflux from microorganisms using fluorescent single-walled carbon nanotube sensor arrays

2017; Nature Portfolio; Volume: 12; Issue: 4 Linguagem: Inglês

10.1038/nnano.2016.284

1748-3395

Markita P. Landry, Hiroki Ando, Allen Y. Chen, Jicong Cao, Vishal I. Kottadiel, Linda Chio, Darwin Yang, Juyao Dong, Timothy K. Lu, Michael S. Strano,

Advanced Biosensing Techniques and Applications

A distinct advantage of nanosensor arrays is their ability to achieve ultralow detection limits in solution by proximity placement to an analyte. Here, we demonstrate label-free detection of individual proteins from Escherichia coli (bacteria) and Pichia pastoris (yeast) immobilized in a microfluidic chamber, measuring protein efflux from single organisms in real time. The array is fabricated using non-covalent conjugation of an aptamer-anchor polynucleotide sequence to near-infrared emissive single-walled carbon nanotubes, using a variable chemical spacer shown to optimize sensor response. Unlabelled RAP1 GTPase and HIV integrase proteins were selectively detected from various cell lines, via large near-infrared fluorescent turn-on responses. We show that the process of E. coli induction, protein synthesis and protein export is highly stochastic, yielding variability in protein secretion, with E. coli cells undergoing division under starved conditions producing 66% fewer secreted protein products than their non-dividing counterparts. We further demonstrate the detection of a unique protein product resulting from T7 bacteriophage infection of E. coli, illustrating that nanosensor arrays can enable real-time, single-cell analysis of a broad range of protein products from various cell types. Nanosensor arrays based on single-walled carbon nanotubes can detect protein efflux from single, isolated microorganisms in real time, allowing the dynamics of genetic transfection and influence of reproduction to be measured.