Near-infrared light-controlled catalytic hairpin assembly fluorescent biosensor for the sensitive and specific detection of fibroblast activation protein

Figures

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  Scheme 1. Schematic diagram of the developed bioprobe for the detection of FAP.

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  Fig. 1. (A) TEM image of the core UCNP (scale: 50 nm); (B) TEM image of the core–shell UCNP (scale: 100 nm); (C and D) EDS images of the core–shell UCNP; (E) XRD patterns of the core UCNP and core–shell UCNP; (F) FTIR spectra of the core UCNP, core–shell UCNP, and Cit-UCNP; (G) zeta potential changes at different modification stages.

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  Fig. 2. (A) Schematic illustration of the NIR light-controlled CHA fluorescence sensing mechanism for FAP detection; (B) fluorescence emission spectra of the core UCNP and core–shell UCNP under 808 nm excitation; (C) energy transfer principle diagram of the core–shell UCNP structure; (D) PAGE analysis of the photoactivation and CHA reaction mechanism (lane 1: S1-SPT duplex; lane 2: S1-SPT + FAP; lane 3: U–H1; lane 4: U–H1 under 808 nm irradiation; lane 5: H2; lane 6: S1-SPT + FAP + U–H1 (without H2); lane 7: complete system (S1-SPT + FAP + U–H1 + H2) under 808 nm irradiation); (E and F) fluorescence emission spectra of the sensing system under different experimental conditions measured at 663 nm.

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  Fig. 3. (A) Full fluorescence emission spectra under different 808 nm illumination times; (B) the corresponding fluorescence intensity at 663 nm; (C) full fluorescence emission spectra at different H1 dosages; (D) the corresponding fluorescence intensity at 663 nm; (E) full fluorescence emission spectra at different H2 dosages; (F) the corresponding fluorescence intensity at 663 nm.

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  Fig. 4. (A) Fluorescence spectra of the system with varying concentrations of FAP; (B) linear relationship between the fluorescence recovery efficiency and FAP concentration; (C and D) degree of fluorescence recovery of the system in the presence of different proteins; (E) stability test results for 10 consecutive days (every 48 h); (F) intra-batch and inter-batch repeatability evaluation of the sensor.