Portable tri-color ratiometric fluorescence paper sensor for intelligent visual detection of dual-antibiotics and aluminium ion.

The toxicological effect between co-existed antibiotics and metal ions was dangerous to the ecological environment and public health. However, the rapid quantification tools with convenience, accuracy and low cost for the detection of multiple targets were still challenging. Herein, a portable tri-color ratiometric fluorescence paper sensor was constructed by coupling of blue carbon dots and fluorescence imprinted polymer for down/up conversion simultaneous detection of tetracycline and sulfamethazine. Interestingly, the cascade detection of aluminum ion was also realized based on the individual detection system of tetracycline without the assistance of complex coupling reagents. The detection limits of smartphone method for the visual detection of tetracycline, sulfamethazine and aluminum ion were calculated as 0.014 µM, 0.004 µM and 0.019 µM, respectively. The portable fluorescence paper sensor was applied for the visual detection of tetracycline, sulfamethazine and aluminum ion in actual samples successfully with satisfactory recoveries. With the advantages of rapidness, low cost, and portability, the developed portable fluorescence paper sensor provided a new strategy for the visual real-time detection of multiple targets.

Smartphone-assisted colorimetric dual-mode sensing system based on europium-doped metal-organic frameworks for rapid on-site visual detection of Fe3+ and doxycycline.

Exploring a rapid, sensitive, low-cost, in-situ intelligent monitoring multi-target fluorescence detection platform is important for food safety and environmental monitoring. A dual-mode ratiometric fluorescence sensing system integrated with a smartphone based on a luminescent metal-organic framework (NH2-MIL-53) and CdTe/Eu was developed for visual, in-situ analysis of Fe3+ and doxycycline (DOX) in this paper. Interestingly, with increasing Fe3+ concentration, the fluorescence sensing system exhibits dual-emission with CdTe QDs at 540 nM as the response signal and NH2-MIL-53 at 438 nm as the reference signal, resulting in a significant color shift of fluorescence color from blue-green to blue, with a linear range of 5--1550 nM and a detection limit of 1.08 nM. In the presence of DOX, the blue fluorescence of NH2-MIL-53 and the green fluorescence of CdTe QDs were quenched respectively by the internal filtering effect and the photoelectron transfer effect. While DOX enhances the red fluorescence of Eu3+ by the antenna effect, forming a triple-emission fluorescence sensor. The visual color of this fluorescent sensor shifted from blue green to grey to pink-white to pink to fuchsia to red as the DOX concentration increased with a detection limit of 0.11 nM. Furthermore, the developed intelligent sensing platform achieved real-time in-situ detection of Fe3+ and DOX with detection limit of 1.47 nM and 6.43 nM, respectively. The platform was applied to detection actual samples with satisfactory results, which proved a promising application for real-time on-site food safety monitoring and human health monitoring.

Integrating Intelligent Logic Gate Dual-Nanozyme Cascade Fluorescence Capillary Imprinted Sensors for Ultrasensitive Simultaneous Detection of 2,4-Dichlorophenoxyacetic Acid and 2,4-Dichlorophenol.

Herein, a dual-nanozyme cascade catalysis triemission fluorescence capillary imprinted sensor integrated with intelligent logic gates was constructed for simultaneous detection of 2,4-dichlorophenoxyacetic acid (2,4-DA) and 2,4-dichlorophenol (2,4-DCP). The novel nanozyme fluorescence organic framework (Bi, Co-MOF) was grafted on the surface of Fe3O4 modified with histidine to form a nanozyme composite (FBM) with dual-enzyme activity, which was imprinted with 2,4-DA to prepare a fluorescence molecularly imprinted polymer (FBM@MIP). Carbon dots (CDs) coupling with FBM@MIP (FBM@MIP/CDs) was inhaled into a capillary to construct a dual-nanozyme capillary imprinted sensor directly. The FBM@MIP/CDs capillary sensor realized to detect 2,4-DA and 2,4-DCP simultaneously within a linear concentration range of 1.0 × 10-12-1.2 × 10-9 M and 1.0 × 10-12-4.8 × 10-9 M with the detection limit of 0.75 and 0.68 pM, respectively. Interestingly, a smartphone-assisted portable capillary fluorescence intelligent sensing platform was developed that can detect 2,4-DA and 2,4-DCP visually without tedious operations such as soaking and drying. Combined with a smartphone, the linear relationships between RGB ratios and concentrations of 2,4-DA and 2,4-DCP were established with the detection limit of 0.93 and 0.81 pM, respectively. The integrated logic gates provided a promising way for intelligent sensing of multiple targets simultaneously, which provided a new strategy for ultrasensitive simultaneous detection of multiple pollutants with a microvolume (18 µL/time) in complex environments.

Bimetallic nanozyme triple-emission fluorescence intelligent sensing platform-integrated molecular imprinting for ultrasensitive visual detection of triclosan.

Triclosan (TCS) is an endocrine disruptor, which has been widely used in daily chemicals, resulting in the potential risk to the ecosystem and human health. Herein, a smartphone-integrated bimetallic nanozyme triple-emission fluorescence capillary imprinted sensing system was developed for ultrasensitive and intelligent visual microanalysis of TCS. Carbon dots (CDs) and bimetallic organic framework (MOF-(Fe/Co)-NH2) were used as fluorescence sources to synthesize nanozyme fluorescence molecularly imprinted polymer (MOF-(Fe/Co)-NH2@CDs@NMIP), which oxidized o-phenylenediamine to 2,3-diaminophenazine (OPDox), resulting in the derivation of a new fluorescence peak at 556 nm. In the existence of TCS, the fluorescence of MOF-(Fe/Co)-NH2 at 450 nm was restored, the fluorescence of OPDox at 556 nm was suppressed, and the CDs fluorescence of at 686 nm remained constant. The color of triple-emission fluorescence imprinted sensor varied from yellow to pink to purple to blue. The response efficiency (F450/F556/F686) of this sensing platform based on the capillary waveguide effect demonstrated a significant linear relationship toward the concentration of TCS ranged from 1.0 × 10-12 to 1.5 × 10-10 M with the LOD of 8.0 × 10-13 M. Compared with dual-emission capillary fluorescence sensor, this sensing system has higher sensitivity and richer visual color. Combined with the smartphone-integrated portable sensing platform, the color of fluorescence was transformed into an RGB value to calculate TCS concentration with the LOD of 9.6 × 10-13 M, providing a novel method for intelligent visual microanalysis (18 µL/time) of environmental pollutants.

Smartphone-integrated tri-color fluorescence sensing platform based on acid-sensitive fluorescence imprinted polymers for dual-mode visual intelligent detection of ibuprofen, chloramphenicol and florfenicol.

The abuse of multiple antibiotics and anti-inflammatory drugs can harm the ecological environment and human health. Herein, a smartphone-integrated tri-color fluorescence sensing platform based on acid-sensitive fluorescence imprinted polymers was proposed for dual-mode visual intelligent detection of ibuprofen (IP), chloramphenicol (CAP), and florfenicol (FF). In this research, the dual-mode of tri-color ratiometric fluorescence imprinted sensor (TC-FMIPs) was realized at different pH environments for the detection IP, CAP, and FF. The fluorescence peak at 551 nm of TC-FMIPs was quenched in the presence of IP solution and fluorescence peak at 687 nm was quenched in the presence of CAP phosphate buffer solution (PBS, pH 7.0), while the fluorescence peak at 433 nm kept stable. Interestingly, the TC-FMIPs has a peroxidase-like activity, in which a new fluorescence peak at 561 nm was quenched and the fluorescence peak at 433 nm increased gradually with the addition of FF solution in pH 4.0 PBS. The TC-FMIPs showed a low detection limit of 10 pM, 8.5 pM, and 5.5 nM for IP, CAP, and FF, respectively. Additionally, a smartphone was used to capture of fluorescence colors and read out the RGB values for intelligent detection of IP, CAP, and FF, in which the detection limit was calculated as 15 pM, 12 pM and 7 nM toward IP, CAP and FF, respectively. The smartphone-integrated tri-color fluorescence sensing platform was developed for dual-mode visual intelligent detection of IP, CAP and FF successfully, which provided a new strategy for multi-target detection in the complex environment.

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.

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.

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.

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 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.