Elsevier

Biosensors and Bioelectronics

Volume 194, 15 December 2021, 113598
Biosensors and Bioelectronics

Background-free sensing platform for on-site detection of carbamate pesticide through upconversion nanoparticles-based hydrogel suit

https://doi.org/10.1016/j.bios.2021.113598Get rights and content

Highlights

  • Hydrogel portable suit was constructed for on-site monitoring of carbaryl.

  • Smartphone-based detector was designed for accurate quantitation analysis.

  • Background-free performance was achieved by using upconversion nanoparticles.

  • Detection limit of carbaryl was 0.5 ng mL-1.

  • Hydrogel portable suit performed good reliability in tea samples.

Abstract

On-site monitoring of carbamate pesticide in complex matrix remians as a challenge in terms of the real-time control of food safety and supervision of environmental quality. Herein, we fabricated robust upconversion nanoparticles (UCNPS)/polydopamine (PDA)-based hydrogel portable suit that precisely quantified carbaryl in complex tea samples with smartphone detector. UCNPS/PDA nanoprobe was developed by polymerization of dopamine monomers on the surface of NaErF4: 0.5% Tm3+@NaYF4 through electrostatic interaction, leading to efficient red luminescence quenching of UCNPS under near-infrared excitation, which circumvented autofluorescence and background interference in complicated environment. Such a luminescence quenching could be suppressed by thiocholine that was produced by acetylcholinesterase-mediated catalytic reaction, thus enabling carbaryl bioassay by inhibiting the activity of enzyme. Bestowed with the feasibility analysis of fluorescent output, portable platform was designed by integrating UCNPS-embedded sodium alginate hydrogel with 3D-printed smartphone device for quantitatively on-site monitoring of carbaryl in the range of 0.5–200 ng mL-1 in tea sample, accompanied by a detection limit of 0.5 ng mL-1. Owing to specific UCNPS signatures and hydrogel immobilization, this modular platform displayed sensitive response, portability and anti-interference capability in complex matrix analysis, thus holding great potential in point-of-care application.

Introduction

Carbamate pesticides perform a key role in pests controlling and diseases precaution for effectively guaranteeing and boosting production of agriculture, forestry and animal husbandry (Bazrafshan et al., 2017; Chen et al., 2017b; Cwielag-Piasecka et al., 2017; Zhu et al., 2018). Although carbamate pesticides with relatively low toxicity and short half-life period, public safety hazard arising from abuse and long-term accumulation has regarded as a major concern. Analogous to the toxicity mechanism of organophosphorus pesticides, carbamate pesticides could act as the immediate blockers of cholinesterase activity (Chen et al., 2021b; Sun et al., 2013). Exposure to carbamate pesticides could trigger cerebral edema, coma and respiratory depression. International Agency for Research on Cancer (IARC) has listed carbamate pesticides as a Class 2A carcinogen since that they can transformed into nitrosobenzene compounds under acidic conditions. Hence, accurate quantification of carbamate pesticides residuals is highly disired for public health (Larsen et al., 2017; Tang et al., 2021).

Conventional methods including gas/liquid chromatography and mass spectrometry as ISO 17025 certification standards have been served for pesticides monitoring (Ge et al., 2020; Rajski et al., 2019; Zheng et al., 2019). Despite these technologies euipping with high accuracy, the complex operation, high equipment costs and time-consuming process made it unavailable in point-of-care (POC) application, particularly in the case of limited or noncentralized resources (Jin et al., 2019). In consideration of these limitations, vast efforts have been made for exploring alternative schemes for profiling pesticides residuals, aiming at portability and simplicity (Yu et al., 2019). Paper-based POC technique that takes target-triggered color variation as the principle is utilized for pesticides analysis by naked eye identification, being featured with easy operation and cost-saving immobilized carrier (Sheng et al., 2021; Yan et al., 2017). For instance, fluoremetric test strips-based device was fabricated for visual sensing organophosphorus pesticides by using luminogen@manganese dioxide core-shell nanomaterial (Chen et al., 2021a). Despite no requirement of expensive apparatus, trace pesticide was unattainable detection because of the restrictions of qualitative and semiquantitative identification. Due to the difference of sensitivity of eye toward light, false-negative results may emerge by judging the brightness variations of device. Another encountered problem was that test strips were easily damaged and susceptible to environmental conditions, leading to poor stability. Stimuli-responsive hydrogel enabled myriad applications from cell/tissue scaffolds, drug/gene delivery carriers and biosensors, equiped with functional characteristics including internal cross-linking microchannels, high loading capacity and mechanical stability (Jin et al., 2020; Vazquez-Gonzalez and Willner, 2020; Wang et al. 2019, 2021; Zhang et al., 2020). It is confirmed that the formed hydrogel cross-linked network not only maintained the structure stability and prevented dissolution against changeable outer circumstance, but also allowed target molecules to diffuse well in porous structure (Mohamed et al., 2019; Ogura and Rehm, 2019). For example, bimetallic AuPt hydrogel with surface functionalization was applied to immobilized enzyme, exhibiting good electrochemical performance toward target (Wu et al., 2019). Taking fluorescence as output signal, our group constructed copper nanoparticles-based hydrogel systems for dimethoate response, overcoming poor stability of nanomaterials (Kong et al., 2019). However, these strategies with blue/green-emission fluorescence probes were susceptible to background interference from complex matrix including secondary metabolites and plant pigments, thus frequently resulting in false-positive reaction. Furthermore, fluorescence hydrogel images were recorded under full-exposure ultraviolet irradiation, which inevitably caused strong color interference from excitation light unless introuducing a applicable cut-off filter (Chen et al., 2019; Su et al., 2020). Thereby exploring alternative fluorescence materials with low background noise still remains a daunting challenge for the development of pesticides biosensors.

Lanthanide doped upconversion nanoparticles (UCNPS) that convert near-infrared (NIR) irradiation into ultraviolet, visible or NIR emission through nonlinear optical processes serve as an ideal nanoprobe candidate for biosensors owing to high photo/chemical stability and autofluorescence-free effect (Ke et al., 2019; Mei et al., 2016). Unlike conventional fluorescence nanomaterials (organic dyes, quantum dots and metal nanoclusters) that are excited by high-energy ultraviolet light or visible light, which might cause autofluorescence and photic damage of biological samples, resulting in low signal-to-noise ratio and reduced sensitivity. Meanwhile, biological matrix possessed low absorption of NIR light, thereby reducing the excitation light loss. Currently reported UCNPS-based analytical technique was frequently fabricated by employing test strip as the carrier, which was confined to qualitative visualization through blue/green luminescence emission (He et al., 2021; You et al., 2017; Zhang et al., 2019). The utilized blue/green upconversion luminescence maybe absorbed and scattered by the substrate and complex sample-containing chromophores. Compared with blue/green upconversion luminescence, red upconversion luminescence with the strong penetration ability was located in the optical window of biology, which could efficiently avoid background interference from complex matrix and improve the detection efficiency. In addition, it can be easily interfered to measurement signal on blue/green/yellow-region emission due to strong attenuation of visible light in biological systems, resulting in low emission collection.

Driven by the aforementioned development, herein we constructed an on-site analysis paltform for sensing carbamate pesticides (carbaryl as model target) by integrating sodium alginate hydrogel immobilized UCNPS (NaErF4: 0.5% Tm3+@NaYF4) with handheld smartphone detector (Scheme 1). Employing inert shell coating strategy and Tm3+-mediated transient energy trapping could circumvente the concentration quenching effect for activator (Er3+) and realize high-efficiency upconversion monochromic red fluorescence (NIR-to-R signal). Signal indicator of UCNPS and enzyme substrate were initially encapsulated in sodium alginate hydrogel, followed by dopamine (DA) triggered auto-polymerization and deposition on the surface of UCNPS. Note that the formed polydopamine (PDA) layer with broad absorbance possessed the ability of efficient quenching toward UCNPS. Thiocholine (TCh) produced by acetylcholinesterase (AChE) controlled-catalytic reactions could restrain the polymerization process of DA. The carbaryl suppressed the activity of AChE, accompanied by the fluorescence signal quenching. Based on the NIR-to-R signal response toward carbaryl, on-site quantification of pesticide was performed by a 3D-printed auxiliary equipment. The fluorescence photographs were captured by smartphone as color shooter and analyzed by ImageJ software, whose hue intensity was in correlation with the content of target. As far as we know, the integration of UCNPS and hydrogels was the first time to use for on-site pesticides detection. The detection of carbaryl in eleven kinds of tea samples was realized by using background-free UCNPS/PDA system, revealing the great potential of on-site food safety monitoring.

Section snippets

Preparation of core-shell UCNPS (NaErF4: 0.5% Tm3+@NaYF4)

In a typical procedure, 0.15168 g YCl3·6H2O was firstly added into a 100 mL flask including 6 mL of oleic acid and 15 mL of 1-octadecene, then stirred for 30 min under nitrogen flowing. When heated to 150 °C, the mixture was remained for 45 min until it completely dissolved. After cooling, methanol which contained 0.05 g NaOH and 0.074 g NH4F was dropwise added to above solution, and then heated to 70 °C for 30 min. Under nitrogen protection, 2 mL of the core UCNPS was dropwise injected and

Characterization of UCNPS/PDA architectures

Core-inert shell UCNPS (NaErF4: 0.5% Tm3+@NaYF4) with an intensely suppressed concentration quenching for the activator (Er3+) and high-efficiency upconversion red luminescence was synthesized through a solvothermal method. Doping Tm3+ as a transient energy trapping center can facilitate collection and preservation of excitation energy by Er3+ ions (Chen et al., 2017a). The hexagonal phase nanoparticles were verified by XRD data (Fig. 1A), in which the diffraction peaks were consistent with the

Conclusion

In summary, we constructed a portable and cost-effective sensing hydrogel suit for accurate screening of carbaryl by employing UCNPS embedded sodium alginate hydrogel with miniaturized readout devices. By utilizing NIR-to-R signatures of UCNPS, a simple hydrogel-based platform with preferable sensitive response toward carbaryl achieved an LOD of 0.5 ng mL-1 in tea samples. What is worth mentioning is that the anti-interference ability resulted from the NIR-excitation and red-emission of UCNPS

CRediT authorship contribution statement

Dandan Su: Conceptualization, Methodology, Writing – original draft. Xu Zhao: Conceptualization, Methodology, Writing – original draft. Xu Yan: Conceptualization, Methodology, Writing – original draft, Funding acquisition, Supervision. Xiaosong Han: Methodology. Zhifang Zhu: Methodology. Chenguang Wang: Writing – original draft. Xiaoteng Jia: Writing – original draft. Fangmeng Liu: Methodology. Peng Sun: Methodology. Xiaomin Liu: Writing – original draft, Supervision. Geyu Lu: Funding

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

The authors would like to acknowledge the financial support by the National Natural Science Foundation of China (No. 62171194, 21806051, U2003127, 61831011, 61722305, 61833006 and 61875191), the National Key Research and Development Program of China (No. 2016YFC0207300), China Post-doctoral Science Foundation funded project (No. 2020M670857 and 2021M691217), Natural Science Foundation of Jilin Province (20200201021JC and 20200201218JC). Jilin Province Science and Technology Development Plan

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