A novel biosensor based on antibody controlled isothermal strand displacement amplification (ACISDA) system

Recent Trends in Biosensors for Quinolone Detection: A Comprehensive Review

“…aTFs undergo conformation changes upon binding to a ligand, which alters their affinity to DNA motifs. Due to their innate architecture, they can act as a switch to turn genes on and off and are therefore widely used in fields such as synthetic biology [80][81][82]. Isothermal amplification strategies such as SDA have been gaining attention in recent years as the new "gold standard" for nucleic acid amplification.…”

“…This comes with many benefits such as the possibility for high throughput analysis, single workflows and the mimicking of in vivo mechanisms [83]. Liu and colleagues used SDA with aTFs and developed a novel biosensor based on the antibody controlled isothermal strand displacement amplification (ACISDA) system [81,84,85]. They explored a novel approach based on antigen-labelled DNA as the primer for SDA combined with a competitive reaction: without antigen in the sample, the antibodies would bind to the labelled primer, preventing the SDA reaction from happening.…”

“…In the presence of antigen in the sample, the antibodies will dissociate from the modified primer, which in turn triggers the SDA reaction to start. The SDA reaction produces nucleotide sequences that spontaneously change conformation and fold into G-quadruplex structures that bind with the dye Thioflavin T (ThT) to augment the output fluorescent signal [81,[86][87][88]. Using this creative system, in 90 min, Liu and colleagues were able to detect the quinolone norfloxacin in a linear range of 0.1-500 ng/mL with a detection limit of 0.04 ng/mL.…”

“…Using this creative system, in 90 min, Liu and colleagues were able to detect the quinolone norfloxacin in a linear range of 0.1-500 ng/mL with a detection limit of 0.04 ng/mL. The system demonstrated good stability after it was pre-distributed and freeze-dried at 4 • C for one month, and would therefore facilitate the detection of norfloxacin in field testing [81].…”

A cascade signal-amplified fluorescent biosensor combining APE1 enzyme cleavage-assisted target cycling with rolling circle amplification

“…However, most enzymes employed are external proteases, which are not well-suited for in vivo amplification needs. 10–12 A promising exploration lies in leveraging endogenous enzymes within the body to construct signal amplification strategies.…”