A rapid and reliable immunochromatographic strip for detecting paraquat poinsoning in domestic water and real human samples

Highlights

• This is the first PQ-targeted test strip designed for environmental water and multiple human samples.

• The visual limit of detection of the proposed PQ strip is as low as 10 ng/mL

• The PQ strip has the excellent advantages in testing time, specificity and stability.

• The performance of the PQ strips have been assessed in multicenter in China.

Abstract

Paraquat (PQ) is one of the most commonly used herbicides, but it has polluted the environment and threatened human health through extensive and improper usage. Here, a new naked-eye PQ immunochromatographic strip was developed to recognize PQ in domestic water and real human samples within 10 min based on a novel custom-designed anti-PQ antibody. The PQ test strip could recognize PQ at a concentration as low as 10 ng/ml, reaching the high-efficiency time-of-flight mass spectrometry detection level and identifying trace amounts of PQ in samples treated with a diquat (DQ) and PQ mixture. Notably, both the performance evaluation and clinical trial of the proposed PQ strips were validated in multiple hospitals and public health agencies. Taken together, our study firstly provide the clinical PQ-targeted colloidal gold immunochromatographic test strip designed both for environment water and human sample detection with multiple advantages, which are ready for environmental monitoring and clinical practice.

Introduction

Paraquat (N, N-dimethyl-4,4-bipyridine dichloride; PQ) is one of the most commonly used herbicides for controlling weeds worldwide (Rashidipour et al., 2019). However, this herbicide can not only lead to the serious pollution of water resources such as groundwater and rivers (Grillo et al., 2014; Leite et al., 2013) but also cause fatal poisoning in humans (Dawson et al., 2010; Karunarathne et al., 2020). According to the World Health Organization (WHO), oral poisoning with PQ has a high mortality rate of 60%–70%, and its min lethal dose in humans is 35 mg/kg (Gawarammana and Buckley, 2011). In addition, chronic exposure to PQ induces dopaminergic loss, which is considered a key risk factor for PD in wild lifes as well as humans (Cristóvão et al., 2020; Vaccari et al., 2019).

Due to its biodegradability, PQ in soil can be rapidly and completely mineralized by soil microorganisms (Roberts et al., 2002). However, with powerful toxicity and environmental persistence, PQ could alter water quality, affect the physiology and biochemistry of non-target organisms (e.g., fish), and contaminate aquatic systems (Ikpesu, 2015). Hence, the development of user-friendly biosensors that can readily monitor the PQ content in water is of interest for environmental monitoring. In human, PQ concentrations in circulating blood and metabolic urine are closely related to the prognosis of patients with PQ poisoning (Qi et al., 1987; Saito et al., 2011). The time of poisoning diagnosis is usually closely related to the survival rate of patients, so a timely evaluation of PQ poisoning can provide important support for public safety and clinical emergency treatment. Therefore, it is very meaningful to establish a rapid, simple, protable and sensitive biosensor to detect PQ in eviroment water and common clinical specimens.

Several conventional analytical methods have been reported for PQ detection in water, food and environmental samples or even biological fluids such as serum, comprising high-performance liquid chromatography (HPLC) (Lu et al., 2016), liquid chromatography tandem mass spectrometry (LC–MS/MS) (Hao et al., 2013a), gas chromatographic tandem mass spectrometry (GCMS) (Gao et al., 2014) and enzyme-linked immunosorbent assays (van Emon et al., 1986). These expensive techniques offer high sensitivity and reliability. However, they are not suitable for rapid testing in random water sampling at any time and emergency poisoning accidents due to the requirement for expensive equipment, trained personnel and time-consuming sample preparation steps.

As one of the most popular rapid test techniques, colloidal gold immunochromatography (GICA) is a mature and reliable chemical analytical technology. However, compared with the mature GICA strip technology that has been widely applied to test infectious diseases (Lin et al., 2011), drugs (Zhou et al., 2014), influenza (Li et al., 2011) and tumor markers (Olding et al., 1984), test strips for small-molecule poisons are rarely seen in hospitals. Due to the lack of immunogenicity of most toxic small-molecule compounds and the inability to directly produce appropriate monoclonal antibodies (Yang et al., 2020), it is difficult to produce colloidal gold strips for small molecule poisons to meet enviroment monitoring and clinical needs. To date, no colloidal gold strip has been used for both water sample and the biological sample detection of PQ.

In this work, aimed at environment-related public safety support and clinical application, we synthesized haptens of PQ, prepared a high-efficiency monoclonal antibody (McAb) and established a one-step PQ test GICA strip with high sensitivity, strong anti-interference and good stability that can directly detect PQ from water and various types of clinical samples. We confirmed the performance of the designed test strip with many domestic medical institutions and public security institutions. Further refinement and specialized mass production of the designed test strip are anticipated, which will provide important support for environment-related public health security and clinical diagnosis.