"Fluorescence-wavelength" label-free POCT tandem with "fluorescence-photothermal" nanobody-immunosensor for detecting BSA and β-lactoglobulin

Shijie Li; Linqing Nie; Lu Yang; Dancai Fan; Junping Wang; Yaozhong Hu; Yan Zhang; Shuo Wang

doi:10.1016/j.foodchem.2023.137019

"Fluorescence-wavelength" label-free POCT tandem with "fluorescence-photothermal" nanobody-immunosensor for detecting BSA and β-lactoglobulin

Food Chem. 2024 Jan 1:430:137019. doi: 10.1016/j.foodchem.2023.137019. Epub 2023 Jul 27.

Authors

Shijie Li¹, Linqing Nie², Lu Yang³, Dancai Fan⁴, Junping Wang⁵, Yaozhong Hu⁶, Yan Zhang⁷, Shuo Wang⁸

Affiliations

¹ Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University, Tianjin 300071, China. Electronic address: lsj930427@126.com.
² Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University, Tianjin 300071, China. Electronic address: 2120211403@mail.nankai.edu.cn.
³ Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University, Tianjin 300071, China. Electronic address: 2120211423@mail.nankai.edu.cn.
⁴ Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University, Tianjin 300071, China. Electronic address: fandancai@163.com.
⁵ State Key Laboratory for Food Nutrition and Safety, Tianjin University of Science and Technology, Tianjin 300457, China. Electronic address: wangjp@tust.edu.cn.
⁶ Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University, Tianjin 300071, China. Electronic address: yzhu@nankai.edu.cn.
⁷ Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University, Tianjin 300071, China. Electronic address: yzhang@nankai.edu.cn.
⁸ Tianjin Key Laboratory of Food Science and Health, School of Medicine, Nankai University, Tianjin 300071, China. Electronic address: wangshuo@nankai.edu.cn.

PMID: 37552900
DOI: 10.1016/j.foodchem.2023.137019

Abstract

Two carbon dots (CDs) (λ_Em = 525 nm, G-CDs and λ_Em = 640 nm, R-CDs) were synthesized from citric acid and urea. The bovine serum albumin (BSA) responsiveness of the R-CDs was used to develop a "fluorescence-wavelength" label-free point of care testing (POCT) for the detection of the milk quality marker BSA with the detection limit (LOD) of 4.89 μg/mL for fluorescence mode and 3.38 μg/mL for wavelength mode. In addition, R-CDs were found to have hydroxyl radical (·OH)-dependent fluorescence quenching properties, and a "fluorescence-photothermal" immunosensor based on nanobodies was constructed by introducing the fluorescence signal of R-CDs@BSA and the photothermal signal of oxTMB for the detection of β-lactoglobulin (β-LG) with the LOD of 0.034 ng/mL for fluorescence mode and 0.075 ng/mL for photothermal mode. The tandem detection of POCT and immunosensor enables the simultaneous and highly sensitive detection of BSA and β-LG after only simple dilution of less than 5 µL of sample.

Keywords: BSA-enhanced red fluorescent carbon dots; Bovine serum albumin; Fluorescence quenching in response to hydroxyl radicals; Fluorescence-photothermal dual-readout; Fluorescence-wavelength dual-readout; β-Lactoglobulin.

MeSH terms

Biosensing Techniques*
Carbon
Fluorescent Dyes
Immunoassay
Lactoglobulins
Quantum Dots*
Serum Albumin, Bovine
Spectrometry, Fluorescence

Substances

Serum Albumin, Bovine
Lactoglobulins
Carbon
Fluorescent Dyes