Ultrasensitive Fluorescent Microsensors Based on Aptamers Modified with SYBR Green I for Visual Quantitative Detection of Organophosphate Pesticides.

Organophosphate pesticides (OPs) are widely utilized in agricultural production, and the residues threaten public health and environmental safety due to their toxicity. Herein, a novel and simple DNA aptamer-based sensor has been fabricated for the rapid, visual, and quantitative detection of profenofos and isocarbophos. The proposed DNA aptamers with a G-quadruplex spatial structure could be recognized by SYBR Green I (SG-I), resulting in strong green fluorescence emitted by SG-I. The DNA aptamers exhibit a higher specific binding ability to target OP molecules through aromatic ring stacking, disrupting the interaction between SG-I and DNA aptamers to induce green fluorescence quenching. Meanwhile, the fluorescence wavelength of G-quadruplex fluorescence emission peaks changes, accompanied by an obvious fluorescence variation from green to blue. SG-I-modified aptasensor without any additive reference fluorescence units for use in multicolor fluorescence assay for selective monitoring of OPs was first developed. The developed aptasensor provides a favorable linear range from 0 to 200 nM, with a low detection limit of 2.48 and 3.01 nM for profenofos and isocarbophos, respectively. Moreover, it offers high selectivity and stability in real sample detection with high recoveries. Then, a self-designed portable smartphone sensing platform was successfully used for quantitative result outputs, demonstrating experience in designing a neotype sensing strategy for point-of-care pesticide monitoring.

Multiemitting Ultralong Phosphorescent Carbonized Polymer Dots via Synergistic Enhancement Structure Design.

Advancing a metal-free room temperature phosphorescent (RTP) material that exhibits multicolor emission, remarkable RTP lifetime, and high quantum yield still faces the challenge of achieving intersystem crossing between singly and triplet excited states, as well as the rapid decay of triplet excited states due to nonradiative losses. In this study, a novel strategy is proposed to address these limitations by incorporating o-phenylenediamine, which generates multiple luminescent centers, and long-chain polyacrylic acid to synthesize carbonized polymer dots (CPDs). These CPDs are then embedded in a rigid B2O3 matrix, effectively limiting nonradiative losses through the synergistic effects of polymer cross-linking and the rigid matrix. The resulting CPD-based materials exhibit remarkable ultralong phosphorescence in shades of blue and lime green, with a visible lifetime of up to 49 s and a high phosphorescence quantum yield. Simultaneously, this study demonstrates the practical applicability of these excellent material properties in anti-counterfeiting and information encryption.

Background-Free and Reversible Upconversion Hydrogel Sensing Platform for Visual Monitoring of Sulfite.

Excessive sulfite usage in food and pharmaceutical production causes respiratory and neurological diseases, underscoring the need for a sensitive and rapid quantification strategy. The portable sensing platform based on a luminescent hydrogel sensor is a powerful tool for the on-site, real-time detection of sulfite ions. However, the lack of recyclability in almost all reaction-based hydrogel sensors increases the application cost. This study constructed a reversible and upconversion nanoprobe combining upconversion nanoparticles (UCNPs) and pararosaniline (PAR) for sulfite detection. The upconversion nanoprobe was further encapsulated in a three-dimensional polyacrylamide hydrogel matrix to create a background-free, reversible hydrogel sensor. The near-infrared excitation of UCNPs avoids the autofluorescence in the hydrogel and real samples. Meanwhile, PAR serves as a specific recognition unit for sulfite ions. After the addition of sulfites, a specific reaction occurs between PAR and sulfites, leading to the recovery of characteristic emission at 540 nm, achieving sensitive detection of sulfite ions. Importantly, this specific reaction is reversible under thermal treatment, allowing the hydrogel sensor to return to its initial state and thus enabling reversible detection of sulfite ions. Furthermore, a portable sensing platform is developed to realize point-of-care, real-time quantitative detection of sulfite ions. The proposed upconversion reversible hydrogel sensor provides a new sensing strategy for the detection of hazardous substances in food and offers new insights into the preparation of reversible, highly sensitive hydrogel sensors.

Two birds with one stone: Ratiometric sensing platform overcoming cross-interference for multiple-scenario detection and accurate discrimination of tetracycline analogs.

Environmental pollution caused by tetracycline antibiotics (TCs) is a major concern for public health worldwide. Trace detection and reliable discrimination of tetracycline and its analogs are consequently essential to determine the distribution characteristics of various tetracycline family members. Here, a dual-response sensor was constructed by integrating the fluorescence emission of fluorescein isothiocyanate (FITC) doped SiO2 and Eu3+. A portable Lab-on-Paper device is further fabricated through probe immobilization, which allows convenient visual detection of tetracycline using a smartphone. In addition, for the coexistence of multiple tetracycline analogs, dimensionality reduction via principal component analysis is applied to the spectra, realizing accurate differentiation of the four most widely used tetracycline analogs (tetracycline (TC), chlortetracycline (CTC), oxytetracycline (OTC), and doxycycline (DOX)). The dual-response nanoplatform enabled a wide-gamut color variation crossing from green to red, with limit of detection (LOD) of 2.9 nM and 89.8 nM for spectrometer- and paper-based sensors, respectively. Analytical performance was examined in multiple real samples, including food, environmental, and biological settings, confirming robust environmental adaptability and resistance. Compared to previous TC sensors, this method has several notable improvements, including improved ecological safety, accessibility, reproducibility, practicality, and anti-cross-interference capacity. These results highlight the potential of the proposed "two birds with one stone" strategy, providing an integrated methodology for synchronous quantitative detection and derivative identification toward environmental contaminants.

TiO2 compact layer induced charge transfer enhancement in a three-dimensional TiO2-Ag array SERS substrate for quantitative and multiplex analysis.

A highly sensitive and uniform surface-enhanced Raman scattering (SERS) substrate is the guarantee for reliable quantitative analysis. Herein, a three-dimensional TiO2-Ag SERS substrate was prepared by growing a TiO2 nanorods (NRs) array on a TiO2 compact layer (c-TiO2), followed by modification with Ag nanoparticles (AgNPs). The synergy between the c-TiO2, semiconductor TiO2 NRs and the plasmonic AgNPs collaboratively endowed it with high sensitivity, in which c-TiO2 effectively blocked the recombination of electrons and holes, and the charge transfer enhancement contributed 10-fold improvement over that without the c-TiO2 substrate. Besides the high sensitivity, the TiO2-Ag hybrid array SERS substrate also showed quantitative and multi-component detecting capability. The limit of detection (LOD) for crystal violet (CV) was determined to be 10-9 M even with a portable Raman instrument. The TiO2-Ag composite structure was extended to detect organic pesticides (thiram, triazophos and fonofos), and the LODs for thiram, triazophos and fonofos were measured to be 10-7 M, 10-7 M and 10-6 M, respectively. In addition, the realistic simulation detecting pesticide residues for a real sample of dendrobium was demonstrated. The sensitive, quantitative and multiplex analysis of the TiO2-Ag hybrid array substrate indicated its great potential in the rapid detection of pesticide residues in real samples.

Multiplex Chroma Response Wearable Hydrogel Patch: Visual Monitoring of Urea in Body Fluids for Health Prognosis.

Visual wearable devices can rapid intuitively monitor biomarkers in body fluids to indicate the human health status and provide valuable reference for further medical diagnosis. However, unavoidable interference factors such as skin color, natural light, and background luminescence can interfere with the visualization accuracy of flexible wearable devices, limiting their practical sensing application. Here, we designed a wearable sensing patch via an embedded upconversion optical probe in a 3D porous polyacrylamide hydrogel, exhibiting a multiplex chroma response to urea based on the inner filter effect, which overcomes the susceptibility to external conditions due to its near-infrared excited luminescence and improves the resolution and accuracy of visual sensing. Furthermore, a highly compatible portable sensing platform combined with a smartphone was designed to achieve in situ rapid quantitative analysis of urea. The limit of detection values of the upconversion optical probe and hydrogel sensor are as low as 1.4 and 30 µM respectively, exhibiting the practicality in different scenarios. The designed sensing patch provides a convenient and accurate sensing strategy for the detection of biomarkers in body fluids and has the potential to be developed into a point-of-care device to provide disease early warning and clinical diagnosis.

Photoinduced Electron Transfer-Triggered g-C3N4\Rhodamine B Sensing System for the Ratiometric Fluorescence Quantitation of Carbendazim.

Assays for carbendazim (Car) with high sensitivity and on-site screening have been urgently required to protect the ecosystem and prevent disease. In this work, a simple, sensitive, and reliable sensing system based on photoinduced electron transfer was established to detect carbendazim utilizing ultrathin graphitic carbon nitride (g-C3N4) nanosheets and rhodamine B (RB). Carbendazim reacts with g-C3N4 by electrostatic interactions to form π-π stacking, and the quenching of the blue fluorescence is caused by electron transfer. While RB works as a reference fluorescence sensor without any fluorescence change, leading to obvious ratiometric fluorescence variation from blue to purple. Under optimal conditions, a favorable linear range from 20 to 180 nM was obtained, with a low detection limit of 5.89 nM. In addition, a portable smartphone sensing platform was successfully used for carbendazim detection in real samples with excellent anti-interference capability, demonstrating the potential applications of carbendazim monitoring.

Hydrogen-bond induced enhanced emission ratiometric fluorescent handy needle for visualization assay of amoxicillin by smartphone sensing platform.

Amoxicillin (AMO) is one of the most commonly used antibiotics, and its abuse in animal husbandry or clinical therapy can pose unpredictable hazards to humans. Therefore, it is crucial to develop a real-time and rapid method to accurately determine AMO content. Here, we designed a fluorescent nanoprobe for qualitative and quantitative AMO determination by using as-synthesized green safe materials of nontoxic red carbon dots (RCDs) and blue carbon dots (BCDs). In the presence of AMO, a reaction promoting hydrogen bonding occurred immediately, resulting in an instant increase in the intensity of the blue fluorescence of BCDs, accompanied by a marked color change from red to blue. For practical application, we designed a nontoxic sensing fluorescent handy needle to directly and quantitatively detect AMO in real samples. This portable and easy-to-use device was demonstrated on a smartphone platform based on 3D printing technology, which offers the advantages of simple production, excellent visualization, fast response, and instant quantitative detection. The device requires an extremely short detection time and has a sensitive detection limit of 2.39 nM. The method presented here enables real-time assessment for food safety, as well as on-site detection under field conditions to track various trace substances for timely health checks.

Lotus leaf mastoid inspired Ag micro/nanoarrays on PDMS film as flexible SERS sensor for in-situ analysis of pesticide residues on nonplanar surfaces.

Conventional surface-enhanced Raman scattering (SERS) molecular detection are based on hard and brittle substrate, which are not suitable for in-situ detection of analytes adsorbed on nonplanar surfaces. Here, we report a simple biomimetic synthesis method to fabricate lotus leaf mastoid structured AgNPs micro/nanoarrays as reliable SERS substrate. By ideal replicating mastoid structure of lotus leaf into a flexible and transparent PDMS film, followed by depositing plasmonic AgNPs, a powerful chemical sensor with high sensitivity and multiplex detecting capability is demonstrated. The employ of periodic mastoid structure array endows the sensor with high signal repeatability (RSD âˆ¼ 8.6 %), solving the general repeatability problem of SERS substrates. In addition, the detailed designed flexible and transparent PDMS substrate is capable of identifying trace analytes on curved surfaces with excellent durability. In the proof-of-concept experiment, a limit of detection (LOD) of (10-5 M to 10-7 M) was achieved on a portable Raman device for three common pesticides residues (thiram, fonofos and triadophos) on dendrobium leaves and stem according to the molecular fingerprint, indicating its excellent in-situ detection capability. Further, the multiplex detection ability of the Ag/PDMS film is also demonstrated by analyzing the mixture of four typical analytes. Benefiting from its high signal uniformity, this flexible Ag/PDMS substrate also showed good quantitative detection capabilities.

A highly transparent and photothermal composite coating for effective anti-/de-icing of glass surfaces.

Anti-/de-icing of glass surfaces is of great importance in present daily life. The long-standing challenge in this field is largely due to the lack of stable multifunctional coatings that can be conveniently and economically constructed on the glass surface, and more importantly, are capable of retaining the original transparency of glass ranging from the visible to the near infrared spectrum. Herein, a direct spraying sol method on the glass surface to prepare a highly transparent and photothermal composite coating is reported. Such multifunctional coating of Cu7S4 nanoparticles/organo-silicone sols has displayed a good photothermal conversion property and hydrophobic property and therefore yields excellent anti-icing and self-melting ice properties. The condensation time of water droplets can be extended to 86 s even at -10 °C, which is 3.42 times delayed relative to ordinary blank glass. And the adhesion strength of ice is largely reduced to 72 KPa, which is as low as ∼1/3 that of ordinary glass. Meanwhile, the subcooling of adhering droplets is reduced to -12 °C under one solar illumination condition and exhibits a rapid de-icing capability. More impressively, the prepared functional coating glass shows an outstanding transmittance of more than 75% in the visible region, while it is over the minimum glass transmittance limit allowed by Safety Standards for Glass (GB9656-2016, China). In addition, the multifunctional photothermal glass coating exhibits good physical/chemical stability, which facilitates the long-term application of the coating in different environments.

A plasmonic AgNP decorated heterostructure substrate for synergetic surface-enhanced Raman scattering identification and quantification of pesticide residues in real samples.

Rapid and on-site Raman spectroscopic identification and quantification of pesticide residues have been restricted to the low instrumental sensitivity of a portable Raman instrument, and no ideal platforms have been reported for analyzing pesticides on real sample surfaces. An efficient method to improve the detection sensitivity is to fabricate a highly sensitive surface-enhanced Raman scattering (SERS) substrate. Here, we present a MOF-derived ZnO@TiO2 heterostructure combined with plasmonic AgNPs as a SERS sensor to achieve synergetic EM and CM enhancement, exhibiting high sensitivity, excellent signal reproducibility (RSD < 5.9%) and superior stability for analysis of model molecules. The SERS sensor achieved a low detection concentration of 10-8 M for both CV and R6G molecular solutions on a portable Raman device. As a proof of concept, we modelled a pesticide residue on real samples of dendrobium leaves. Thiram, triazophos and fonofos solutions were selected as analytes for mimicking the function of on-site analysis. The SERS analytical platform showed not only high sensitivity for single- and multi-component identification, but also quantitative detection of pesticide residues on dendrobium leaves. These preliminary investigations indicate that this SERS analytical platform will allow the development and potential applications in rapid and on-site pesticide analysis.

Enzyme-free and rapid visual quantitative detection for pesticide residues utilizing portable smartphone integrated paper sensor.

Serious toxicity for organisms from pesticide glyphosate (Gly) residues to the ecosystem and human health has become a consensus. Rapid and selective detection of glyphosate, especially using a simple and portable instrument, is highly desired. In this work, we develop a novel enzyme-free rapid and visual ratiometric fluorescence sensor for selectively quantitative detecting glyphosate by integrating the designed blue carbon nanodots (CDs) and gold nanoclusters (Au NCs). The fluorescence of CDs can be quickly quenched via aggregation-caused quenching (ACQ) within 2 s after introducing glyphosate, resulting from the formation of CDs-Gly-CDs complex aggregation. While the Au NCs serve as the reference signal without any change, therefore leading to obvious and instant ratiometric fluorescence variation from blue to pink to orange. The broad linear range was obtained from 0 to 180 nM with a satisfactory detection limit of 4.19 nM. Furthermore, this approach was successfully applied to detect glyphosate in real samples and a portable smartphone platform integrated paper sensor was developed for in-site visual quantitative glyphosate detection, offering a promising strategy for the construction of enzyme-free trace hazard detection system.

A Portable Sensing Platform Using an Upconversion-Based Nanosensor for Visual Quantitative Monitoring of Mesna.

Mesna is an important regional antidote for protecting the urinary system of chemotherapy patients, which requires monitoring its level in real time to ensure the curative effect. The fluorescence method is a powerful tool in real-time detection with the advantages of fast response and visualization. However, the background interference limits its application in biological sensing. Here, we developed a portable sensing platform using an upconversion-based nanosensor for visual quantitative monitoring of mesna in real-time/on-site conditions. The nanosensor was constructed by upconversion nanoparticles (UCNPs) and ethyl violet (EV), in which the UCNPs emitted red and green light, while EV quenched the green light due to the inner filter effect (IFE). The reaction of mesna with EV caused its fading and broke the IFE process, leading to the recovery of green light. By the fluorescence and colorimetric chromaticity variations, the nanosensor achieved a dual-readout detection for mesna with low limits of detection (LODs) of 26 and 48 nM, respectively. Furthermore, a highly compatible sensing platform was fabricated for facile determination of mesna with an LOD of 56 nM, realizing visual quantitative monitoring of the mesna level to ensure the curative effect and providing a new strategy for point-of-care testing of drugs in clinical settings.

Ratiometric fluorescent sensors for nitrite detection in the environment based on carbon dot/Rhodamine B systems.

A novel carbon dot/Rhodamine B-based ratiometric fluorescent probe was developed for a highly sensitivity and selective detection of nitrite (NO2 -). The probe showed colour changes from blue to orange under ultraviolet light in response to NO2 - with a detection limit as low as 67 nM in the range of 0 to 40 µM. A ratiometric fluorescent test paper was successfully prepared using the probe solution, which demonstrated its feasibility towards a rapid and semi-quantitative detection of NO2 - in real samples.

Chromaticity Evolutionary Detection of Food Contaminant Semicarbazide through an Upconversion Luminescence-Based Nanosensor.

Semicarbazide (SEM) is a widespread carcinogenic and neurotoxic food contaminant, originating from the metabolite of antibiotic nitrofurazone, which is used in aquaculture, or thermal decomposition byproduct of a flour blowing agent azodicarbonamide. Although optical detection technologies are powerful tools considering the advantages of fast response and visualization detection, there are few optical nanosensors for highly sensitive and visual assays of SEM due to no luminescence response and UV absorbance of SEM. Herein, an upconversion luminescence (UCL)-based nanosensor was designed for visual detection of SEM with high sensitivity and good selectivity. The nanosensor was constructed by combining upconversion nanoparticles (UCNPs) and phosphomolybdic acid (PMA), which was used as the specific recognition element of SEM. The developed nanosensor exhibited selective absorbance enhancement and UCL quenching behavior with the addition of SEM based on the inner filter effect (IFE). Since the change in absorbance translated into an exponential change in the luminescence, the sensitivity of the nanosensor was greatly improved. The nanosensor realized a highly sensitive and visual response to SEM in the linear range of 0.5-16 µM with a low limit of detection of 58 nM. Moreover, satisfactory recovery values ranging from 90 to 112% in spiked real samples indicated the practical applicability of the nanosensor. The nanosensor designed here provides a sensitive and convenient sensing strategy for visual detection of hazardous substances and is expected to develop the upconversion sensing application in food safety.

Portable Smartphone Platform Based on a Single Dual-Emissive Ratiometric Fluorescent Probe for Visual Detection of Isopropanol in Exhaled Breath.

The components in the exhaled breath have been confirmed to be related to certain diseases, especially studies have shown that isopropanol (IPA) might be closely associated with illnesses such as lung cancer, and are considered as a biomarker. Herein, we designed a portable smartphone platform based on a chemically synthesized ratiometric fluorescent probe for real-time/on-site, sensitive, and quantitative visual detection of IPA in exhaled breath. The fluorescent probe was fabricated by a nicotinamide adenine dinucleotide (NAD+) functional modified onto fluorescent internal standard red carbon dots (RCDs). Whereas, IPA can convert NAD+ into reduced nicotinamide adenine dinucleotide (NADH) through an enzymatic reaction of secondary alcohol dehydrogenase (S-ADH). The electron transfer from IPA to NAD+ emitted a blue emission of NADH, which displayed consecutive color changes from red to light blue. Under optimum conditions, the fluorescent probe shows sensitive responses to IPA with a detection limit as low as 4.45 nM. Moreover, combined with the smartphone color recognizer application (APP), the ratio of fluorescence intensity response was recorded on a blue channel (B)/red channel (R), which has been employed for the visual quantitative determination of IPA with a detection limit of 8.34 nM and a recovery rate of 90.65-110.09% (RSD ≤ 4.83). The method reported here provides a convenient pathway for real-time/on-site and visual detection of IPA in exhaled air and is expected to extend the application of investigation of potential volatile biomarkers for preliminary monitoring and clinical diagnosis.

3D-printed smartphone-based device for fluorimetric diagnosis of ketosis by acetone-responsive dye marker and red emissive carbon dots.

A portable smartphone device is reported that uses 3D printing technology for the primary diagnosis of diseases by detecting acetone. The key part of the device consists of red carbon dots (RCDs), which are used as internal standards, and a sensing reagent (3-N,N-(diacethydrazide)-9-ethylcarbazole (2-HCA)) for acetone. With an excitation wavelength of 360 nm, the emission wavelengths of 2-HCA and RCDs are 443 nm and 619 nm, respectively. 2-HCA effectively captures acetone to form a nonfluorescent acylhydrazone via a condensation reaction occurring in aqueous solution, resulting in obvious color changes from blue-violet to dark red. The detection limit for acetone is 2.62 µM (~ 0.24 ppm). This is far lower than the ketone content in normal human blood (≤ 0.50 mM) and the acetone content in human respiratory gas (≤ 1.80 ppm). The device has good recovery rates for acetone detection in blood and exhaled breath, which are 90.56-109.98% (RSD ≤ 5.48) and 92.80-108.00% (RSD ≤ 5.07), respectively. The method designed here provides a reliable way to provide health warnings by visually detecting markers of ketosis/diabetes in blood or exhaled breath. The portable smart phone device visually detects ketosis/diabetes markers in the blood or exhaled breath through the nucleophilic addition reaction, which effectively captures acetone to form nonfluorescent acyl groups. This will be a reliable tool to warn human health.

A dual-response ratiometric fluorescent sensor by europium-doped CdTe quantum dots for visual and colorimetric detection of tetracycline.

Residues in animal food and drinking water caused by the abuse of antibiotics lead to cell resistance and many chronic diseases in the human body. Therefore, it has become an inevitable trend to develop a fast, easy-to-use, on-site/real-time visualization method for the detection of antibiotics. Herein, we report a dual-response ratiometric fluorescence sensor which is fabricated by chelating europium ions (Eu3+) onto cadmium telluride quantum dots (CdTe QDs) for real-time and visible detection of tetracycline (TC). With the TC addition, the fluorescence of probe can be seen by the naked eye, from green to yellow and finally to red, exhibiting a dosage-sensitive and broad-chromatic detection strategy for TC. The fluorescence intensity ratio of I616/I512 of Eu/CdTe QDs sensor displays a good linear relation to TC concentrations in the range of 0-80 µM with a limit of detection (LOD) of 2.2 nM. In addition, the sensor can visually detect 200 nM TC in actual samples, which is lower than the maximum residue limit (MRL) of the safety standard. The methodology reported here opens a window toward the real applications of fluorescent and shows the wide applicability in pursuing the concepts simple, rapid, visual, and real-time for food safety and environmental protection.

Colorimetric fluorescent paper strip with smartphone platform for quantitative detection of cadmium ions in real samples.

Instrument-free, portable and direct read-out mini-devices have wider application prospects in various fields, especially for real-time/on-site detection in environmental science. Herein, a colorimetric fluorescent sensor for detecting cadmium ions (Cd2+) based on aggregation-induced emission (AIE) was established, fluorescent paper strips integrated with smartphone platform was further designed for the visualization, on-site and quantitative detection of Cd2+. The colorimetric fluorescent sensor was prepared by mixing orange emission glutathione-stabilized gold nanoclusters (AuNCs) with blue emission ethylenediamine functionalized graphene oxide (EDA-GO), and introducing copper ions (Cu2+) to quench the orange emission of AuNCs while the blue emission served as a background reference without color change. The Cd2+ can induce Cu2+-GSH-AuNCs to aggregation and emit orange fluorescence, causing the fluorescent color of the sensor changed from blue to red with the limit of detection (LOD) as low as 33.3 nM in solution. Moreover, fluorescent paper strips integrated with smartphone platform has a sensitive detection of Cd2+ with the LOD of 0.1 µM in rice samples. The method reported here might have great application prospects in real-time monitoring of foods safety and environmental protection.

A Portable Smartphone Platform Using a Ratiometric Fluorescent Paper Strip for Visual Quantitative Sensing.

Instrument-free, portable, and direct read-out mini-devices have wider application prospects in various fields, especially for real-time/on-site sensing. Herein, combined with a paper strip, a smartphone sensing platform integrated with a UV lamp and dark cavity by 3D-printing technology has been developed for the rapid, sensitive, instrument-free, and visual quantitative analysis in real-time/on-site conditions. The platform proved the feasibility for visual quantitative detection of pesticide via a fluorescence "on-off-on" response with a single dual-emissive ratiometric paper strip. Red-emitting CdTe quantum dots (rQDs) were embedded into the silica nanoparticles (SiO2 NPs) as an internal reference, while blue-emitting carbon dots (bCDs) as a signal report unit were covalently linked to the outer surface of SiO2 NPs. The blue fluorescence could be quenched by gold nanoparticles (Au NPs) and then recovered with pesticide. The red (R), green (G), and blue (B) channel values of the generated images were determined by a color recognizer application (APP) installed in the smartphone, and the R/B values could be used for pesticide quantification with a sensitive detection limit (LOD) of 59 nM. The smartphone sensing platform based on 3D printing might provide a general strategy for visual quantitative detection in a variety of fields including environments, diagnosis, and safety monitoring.