Due to the lack of suitable chemical tools, probing the protein-specific glycation is highly challenging. Herein, we present a strategy based on glycation chemical reporter and proximity-induced FRET signal readout for visualizing protein-specific glycation in living cells. We first developed a bioorthogonal glucose analogue, 6-azido-6-deoxy-D-glucose (6AzGlc), as a novel glycation chemical reporter. Two types of DNA probes, glycation conversion probe and protein targeting probe, were designed to attach to glycation adducts and target proteins, respectively. After the protein was glycated by 6AzGlc, two DNA probes were sequentially applied to the target protein, triggering proximityinduced FRET signal readout. This strategy was successfully used to visualize glucose glycation of several proteins, including PD-L1 and integrin. More importantly, this strategy allowed us to analyze corresponding biological functions of glycated protein in the native environment.
Discrimination
of nucleotides serves as the basis for DNA sequencing
using solid-state nanopores. However, the translocation of DNA is
usually too fast to be detected, not to mention nucleotide discrimination.
Here, we utilized polyphenolic TA and Fe3+, an attractive
metal–organic thin film, and achieved a fast and robust surface
coating for silicon nitride nanopores. The hydrophilic coating layer
can greatly reduce the low-frequency noise of an original unstable
nanopore, and the nanopore size can be finely tuned in situ at the nanoscale by simply adjusting the relative ratio of Fe3+ and TA monomers. Moreover, the hydrogen bonding interaction
formed between the hydroxyl groups provided by TA and the phosphate
groups of DNAs significantly increases the residence time of a short
double-strand (100 bp) DNA. More importantly, we take advantage of
the different strengths of hydrogen bonding interactions between the
hydroxyl groups provided by TA and the analytes to discriminate between
two oligonucleotide samples (oligodeoxycytidine and oligodeoxyadenosine)
with similar sizes and lengths, of which the current signal patterns
are significantly different using the coated nanopore. The results
shed light on expanding the biochemical functionality of surface coatings
on solid-state nanopores for future biomedical applications.
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