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Keywords = ratiometric fluorescence QD membrane

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19 pages, 7334 KB  
Article
Molecularly Imprinted Membranes: Dual@MIPs@mbr for On-Site Detection of CA 19-9
by Eduarda Rodrigues, Ana Xu, Paula Sampaio, Rafael C. Castro, David S. M. Ribeiro, João L. M. Santos and Ana Margarida L. Piloto
Sensors 2025, 25(23), 7363; https://doi.org/10.3390/s25237363 - 3 Dec 2025
Viewed by 1155
Abstract
Dual-emission molecularly imprinted membranes (dual@MIPs@mbr) were developed as a proof-of-concept platform for the selective and instrument-free detection of the cancer biomarker carbohydrate antigen 19-9 (CA 19-9). The system integrates a ratiometric fluorescence response by embedding yellow-emitting quantum dots (y-QDs), serving as target-responsive probes, [...] Read more.
Dual-emission molecularly imprinted membranes (dual@MIPs@mbr) were developed as a proof-of-concept platform for the selective and instrument-free detection of the cancer biomarker carbohydrate antigen 19-9 (CA 19-9). The system integrates a ratiometric fluorescence response by embedding yellow-emitting quantum dots (y-QDs), serving as target-responsive probes, and blue-emitting carbon dots (b-CDs), acting as an internal reference, within a CA 19-9-imprinted polymeric matrix. Specific rebinding of CA 19-9 to the imprinted cavities induced selective quenching of the y-QDs while preserving the b-CDs emission, yielding a visible color shift from yellow/green to blue. This behavior enabled the quantification of CA 19-9 over a linear range of 4–400 U mL−1, with a limit of detection of 0.056 U mL−1 in diluted serum. The membranes showed good selectivity against common serum interferents and maintained short-term photochemical stability. Although the method has not yet been validated using real clinical samples, the pronounced ratiometric response and simple visual readout demonstrate its potential as a low-cost, portable sensing approach for future point-of-care cancer biomarker analysis. Full article
(This article belongs to the Section Optical Sensors)
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19 pages, 4150 KB  
Article
Development of Ratiometric Fluorescence Sensors Based on CdSe/ZnS Quantum Dots for the Detection of Hydrogen Peroxide
by Hong Dinh Duong and Jong Il Rhee
Sensors 2019, 19(22), 4977; https://doi.org/10.3390/s19224977 - 15 Nov 2019
Cited by 20 | Viewed by 4275
Abstract
In this study, carboxyl group functionalized-CdSe/ZnS quantum dots (QDs) and aminofluorescein (AF)-encapsulated polymer particles were synthesized and immobilized to a sol–gel mixture of glycidoxypropyl trimethoxysilane (GPTMS) and aminopropyl trimethoxysilane (APTMS) for the fabrication of a hydrogen peroxide-sensing membrane. CdSe/ZnS QDs were used for [...] Read more.
In this study, carboxyl group functionalized-CdSe/ZnS quantum dots (QDs) and aminofluorescein (AF)-encapsulated polymer particles were synthesized and immobilized to a sol–gel mixture of glycidoxypropyl trimethoxysilane (GPTMS) and aminopropyl trimethoxysilane (APTMS) for the fabrication of a hydrogen peroxide-sensing membrane. CdSe/ZnS QDs were used for the redox reaction of hydrogen peroxide (H2O2) via a reductive pathway by transferring electrons to the acceptor that led to fluorescence quenching of QDs, while AF was used as a reference dye. Herein, the ratiometric fluorescence intensity of CdSe/ZnS QDs and AF was proportional to the concentration of hydrogen peroxide. The fluorescence membrane (i.e., QD–AF membrane) could detect hydrogen peroxide in linear detection ranges from 0.1 to 1.0 mM with a detection limit (LOD) of 0.016 mM and from 1.0 to 10 mM with an LOD of 0.058 mM. The sensitivity of the QD–AF membrane was increased by immobilizing horseradish peroxidase (HRP) over the surface of the QD–AF membrane (i.e., HRP–QD–AF membrane). The HRP–QD–AF membrane had an LOD of 0.011 mM for 0.1–1 mM H2O2 and an LOD of 0.068 mM for 1–10 mM H2O2. It showed higher sensitivity than the QD–AF membrane only, although both membranes had good selectivity. The HRP–QD–AF membrane could be applied to determine the concentration of hydrogen peroxide in wastewater, while the QD–AF membrane could be employed for the detection of α-ketobutyrate. Full article
(This article belongs to the Special Issue Fluorescent Biosensors 2019)
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