Ratiometric Fluorescence Capillary Sensor-Integrated Molecular Imprinting for Simultaneous Detection of Two Biological Indicators of Parkinson's Disease.

This work proposed ratiometric fluorescence capillary sensing system-integrated molecular imprinting with highly sensitive and selective detection for two biological indicators of Parkinson's disease (homovanillic acid (HVA) and Al3+). In this research, the silicon carbon quantum dot and the near-infrared CdTe quantum dot as luminescence sources were doped to an imprinted layer, which was attached to the inner surface wall of an amino-functionalized capillary. The fluorescence emissions of the ratiometric fluorescence capillary-imprinted sensor at 434 and 707 nm were quenched by HVA, and only the fluorescence emission at 434 nm was quenched by Al3+. Ratiometric fluorescence capillary sensing system-integrated molecular imprinting was used to detect simultaneously HVA and Al3+ with linearity over 1.0 × 10-9-2.5 × 10-7 and 1.0 × 10-9-1.1 × 10-7 M, respectively. The sensor showcased detection limitations of 8.7 × 10-10 and 9.8 × 10-10 M, indicating that the ratiometric fluorescence capillary sensing system-integrated molecular imprinting had great potential application for detecting HVA and Al3+ in serum and urine samples. The ratiometric fluorescence capillary sensing system-integrated molecular imprinting achieved highly sensitive and selective detection of HVA and Al3+ with a microvolume test dosage of 18 µL, which provided a new way for early diagnosis and disease monitoring of Parkinson's disease.

One-pot synthesis of ternary-emission molecularly imprinted fluorescence sensor based on metal-organic framework for visual detection of chloramphenicol.

In this paper, a ternary-emission fluorescence imprinted polymer was one-pot synthesized by sol-gel method after mixing luminescence metal organic framework, green CdTe and near infrared red CdTe for visual detection of chloramphenicol in food. The ternary-emission fluorescence imprinted sensor showed wider linear range within concentration of 10 pM-0.5 nM and 0.5 nM-4.5 nM, with rapid response time of 3 min and the lower detection limit of 3.8 pM toward chloramphenicol. Meanwhile, NH2-UiO-66 improved the fluorescence sensitivity and response speed, the near-infrared CdTe enhanced the anti-interference ability of the imprinted sensor. Compared with the traditional single-emission and dual-emission fluorescence imprinted sensors, the ternary-emission imprinted sensor provided richer color changes from yellowish green to apricot to orange-salmon to amaranth to purple to final blue. It was applied to detect trace chloramphenicol in food with the recoveries of 98.2-101.2 %, which provided a new way for rapid visual detection of chloramphenicol.

A smartphone-assisted down/up-conversion dual-mode ratiometric fluorescence sensor for visual detection of mercury ions and l-penicillamine.

Establishment of a rapid, sensitive, visual, accurate and low-cost fluorescence detection system to detect multiple targets was of great significance in food safety evaluation, ecological environment monitoring and human health monitoring. In this work, a smartphone-assisted down/up-conversion dual-mode ratiometric fluorescence sensor was proposed based on metal-organic framework (NH2-MIL-101(Fe)) and CdTe quantum dots (CdTe QDs) for visual detection of mercury ions (Hg2+) and L-penicillamine (L-PA), in which NH2-MIL-101(Fe) was used as the reference signal and CdTe QDs was used as the response signal. The down-conversion fluorescence system at excitation wavelength of 300 nm (ex: 330 nm) was used to detect Hg2+ and L-PA, in which the detection limit of Hg2+ was 0.053 nM with the fluorescence color changed from green to blue, and the detection limit of L-PA was 1.10 nM with the fluorescence color changed from blue to green. Meanwhile, the up-conversion fluorescence system at excitation wavelength of 700 nm (ex: 700 nm) was used to detect Hg2+ and L-PA. The detection limits of Hg2+ and L-PA were 0.11 nM and 2.93 nM, respectively. The detection of Hg2+ and L-PA were also carried out based on the color extraction RGB values identified by the smartphone with a detection limit of 0.091 nM for Hg2+ and 8.97 nM for L-PA. In addition, the concentrations of Hg2+ and L-PA were evaluated by three-dimensional dynamic analysis in complex environments. The smartphone-assisted down/up-conversion dual-mode ratiometric fluorescence sensor system provides a new strategy for detection Hg2+ and L-PA in food safety evaluation, environmental monitoring and human health monitoring.

Rapid recognition of di-n-butyl phthalate in food samples with a near infrared fluorescence imprinted sensor based on zeolite imidazolate framework-67.

Di-n-butyl phthalate (DBP) as a plasticizer is widely used in food and chemical industries. It is harm to human health when it appeared in food and water. A novel near-infrared (NIR) fluorescence molecularly imprinted sensor based on CdTe quantum dots and zeolite imidazolate framework-67 was developed with a sol-gel polymerization method for rapid and sensitive determination of DBP in foodstuff rapidly (only in 1.5 min). The fluorescence imprinted sensor provided a rapid detection method for DBP in the linear response concentration range of 0.05-18.0 µM with a low detection limit of 1.6 nM. Compared with previous fluorescence imprinted sensor, it behaved faster response speed and lower detection limit for determination of DBP. The fluorescence imprinted sensor was used to detect DBP in real samples successfully with satisfied recoveries of 97.2-106.4%, suggesting a potential application in food analysis.

A dual-response ratiometric fluorescence imprinted sensor based on metal-organic frameworks for ultrasensitive visual detection of 4-nitrophenol in environments.

A dual-response ratiometric fluorescence imprinted sensor based on visible/near-infrared emission was established for ultrasensitive, selective and visual detection 4-nitrophenol (4-NP). The molecularly imprinted polymer was incorporated in the ratiometric sensing system consisting of visible emission carbon dots@zeolitic imidazolate framework-8 (CDs@ZIF-8) and near-infrared emission cadmium telluride (CdTe) quantum dots. The CDs@ZIF-8 enhanced the emission of CDs and the fluorescence sensing performance. Compared to short wavelength of fluorophore, the near-infrared emission CdTe is less interference caused by auto-fluorescence of sample. The ratiometric fluorescence imprinted sensor exhibited dual response for 4-NP at 420 nm and 703 nm and a wide concentration response range. Moreover, a good linear response was existed in the two concentration ranges of 0.1 pM-3.0 pM and 0.05 µM-30 µM with the detection limit of 0.08 pM and 0.05 µΜ, respectively. Significantly, the fluorescence color changes can be observed from purple to pink to red with the naked eye. The fluorescence quenching mechanism of the ratimetric fluorescence imprinted sensor was discussed in detail. The ratiometric fluorescence imprinted sensor was used to detect 4-NP in various real samples with satisfactory recoveries of 97.5-106.3%, which provided an interesting avenue for the rapid detection of pollutant with high sensitivity, high selectivity and visualization in real environment.

A near-infrared fluorescence capillary imprinted sensor for chiral recognition and sensitive detection of l-histidine.

This work firstly developed a near-infrared fluorescence capillary imprinted sensor with high selectivity and sensitivity for the chiral recognition of l-histidine. The near-infrared fluorescence imprinted polymer prepared by sol-gel method using CdTe quantum dots as the near-infrared fluorescence source was self-sucked into activated capillary to form the fluorescence imprinted capillary. The fluorescence imprinted capillary sensor had higher fluorescence response efficiency. With the superior stability, reproducibility and reusability, the fluorescence capillary imprinted sensor displayed higher selectivity toward l-histidine. Under the optimal conditions, the fluorescence intensity (λex = 370 nm, λem = 695 nm) of the fluorescence capillary imprinted sensor was enhanced in proportion to l-histidine concentration ranged from 0.1 pM to 1.8 pM with a limit of detection of 0.08 pM. Spiking experiment showed that the fluorescence capillary imprinted sensor was successfully used for determination of l-histidine in human urine and serum with the recoveries of 99.6-102.7%. The near-infrared fluorescence capillary imprinted sensor possessed significantly potential for high sensitive detection of l-histidine, which realized trace-level analysis for micro-volume sample and provided promising utility for green chemical.

Imparting down/up-conversion dual channels fluorescence to luminescence metal-organic frameworks by carbon dots-induced for fluorescence sensing.

The rapid and simple synthesis of highly efficient multi-emission luminescent metal-organic frameworks (LMOFs) with down/up-conversion fluorescence properties becomes critical in potential optical sensing. Here, we present a luminescent dual-ligand co-assisted strategy to one-pot prepare LMOFs for multiplex fluorescence sensing using carbon dots (CDs) and 2-methylimidazole (2-MIM) as dual-ligand to induce Zn2+ on zeolitic imidazolate framework-8 surface (CDs/MIM-Zn). The CDs/MIM-Zn exhibited efficient fluorescence-enhanced dual channels triple-emission with Stokes and anti-Stokes type excitation profiles. With the assistance of Stokes and anti-Stokes type optical property of CDs and the intrinsic porosity of MOFs structure, a rapid and sensitive dual-channel detection excited at 370 nm and 790 nm was performed to fluorescence turn off-on detect metal ions and reduced glutathione in real blood samples with the satisfactory recoveries of 98.3-106.4%. The dual channels triple-emission strategy ensured multiplex detection of more analytes in parallel.

Down/up-conversion dual-mode ratiometric fluorescence imprinted sensor embedded with metal-organic frameworks for dual-channel multi-emission multiplexed visual detection of thiamphenicol.

The establishment of a fluorescence sensing system for sensitive and selective visual detection of trace antibiotics is of great significance to food safety and human health risk assessment. A simple and rapid one-pot strategy was developed successfully to synthesize a down/up-conversion dual-excitation multi-emission fluorescence imprinted sensor for dual-channel thiamphenicol (TAP) detection. In this strategy, the metal-organic frameworks were in situ incorporated into the fluorescence imprinted sensor, guiding the coordination induced emission of abiotic carbon dots and signal-amplification effect of fluorescence sensing. Under dual-excitation (370 nm and 780 nm), the fluorescence imprinted sensor exhibited a dual-channel fluorescence response toward TAP with two-part linear ranges of 5.0 nM-6.0 µM and 6.0 µM-26.0 µM. Significantly, the fluorescence color ranged from blue to purple to red can be observed with the naked eye. The results of the dual-channel TAP determination in actual samples by the fluorescence imprinted sensor indicated that the fluorescence imprinted sensor provided a sensitive, selective, and multiplexed visual detection of TAP in complex sample.

A near infrared fluorescence imprinted sensor based on zinc oxide nanorods for rapid determination of ketoprofen.

A novel near infrared fluorescence imprinted sensor based on polyethyleneimine passivated copper-doped CdS quantum dots and zinc oxide nanorods for rapid recognition of ketoprofen was successfully prepared by sol-gel imprinting technology. The results showed that the copper-doped CdS quantum dots passivated with polyethyleneimine could improve the fluorescence lifetime and stability. Zinc oxide nanorods as carriers could improve the fluorescence response speed and sensitivity of the imprinted sensor toward ketoprofen. And the fluorescence imprinted sensor could rapidly recognize ketoprofen in just 1.0 minute. Under optimum conditions, the fluorescence intensity of the fluorescence imprinted sensor was quenched linearly by ketoprofen in the concentration range of 0.05-35.5 µM with a detection limit of 1.36 nM. The fluorescence response mechanism of the fluorescence imprinted sensor toward ketoprofen was discussed in detail, and the fluorescence quenching of the fluorescence imprinted sensor by ketoprofen was attributed to the electron transfer. The fluorescence imprinted sensor was applied to recognize ketoprofen in tap water, lake water, waste water and human urine samples rapidly with the recoveries of 97.3-103.7%. The near infrared fluorescence imprinted sensor provided a new reliable method for rapid and sensitive recognition of drugs in complex samples selectively.

An eco-friendly imprinted polymer based on graphene quantum dots for fluorescent detection of p-nitroaniline.

An eco-friendly fluorescent molecularly imprinted polymer anchored on the surface of graphene quantum dots (GQDs@MIP) was developed with an efficient sol-gel polymerization for highly sensitive and selective determination of p-nitroaniline (p-NA). The GQDs@MIP was characterized in detail by Fourier-transform infrared, fluorescence spectrometer, scanning electron microscope, transmission electron microscope and ultraviolet spectrophotometer. The results showed that the imprinted layer was successfully grafted on the surface of the GQDs. The fluorescence of the GQDs@MIP is efficiently quenched when p-NA recombines with the imprinting sites based on the photo-induced electron transfer fluorescence quenching mechanism. A good linear relationship was obtained between the fluorescence quenching efficiency of the GQDs@MIP and the concentration of p-NA in the range of 0-15.0 µM with a correlation coefficient of 0.99. The practicability of the proposed method in real samples was successfully evaluated through monitoring p-NA in water and fish samples with satisfactory recovery. The developed method provides a feasible and eco-friendly strategy to fabricate MIPs anchored on GQDs with good fluorescence properties for sensitive detection of organic pollutants in complex samples.