Development and Clinical Validation of a Sensitive Lateral Flow Assay for Rapid Urine Fentanyl Screening in the Emergency Department

Rapid and Sensitive Detection of Fentanyl and Its Analogs by a Novel Chemiluminescence Immunoassay

BACKGROUND

Abuse of fentanyl and its analogs is a major contributor to the opioid overdose epidemic in the United States, but detecting and quantifying trace amounts of such drugs remains a challenge without resorting to sophisticated mass spectrometry-based methods.

METHODS

A sensitive immunoassay with a sub-picogram limit of detection for fentanyl and a wide range of fentanyl analogs has been developed, using a novel high-affinity antibody fused with NanoLuc, a small-size luciferase that can emit strong and stable luminescence. When used with human urine samples, the assay has a sub-picogram limit of detection for fentanyl, with results fully concordant with LC-MS.

RESULTS

When applied to clinical samples, the novel chemiluminescence immunoassay can detect low positive fentanyl missed by routine screening immunoassays, with a limit of detection of 0.8 pg/mL in human urine. When applied to environmental samples, the assay can detect levels as low as 0.25 pg fentanyl per inch2 of environment surface. Assay turnaround time is less than 1 h, with inexpensive equipment and the potential for high-throughput automation or in-field screening.

CONCLUSIONS

We have established a novel assay that may have broad applications in clinical, environmental, occupational, and forensic scenarios for detection of trace amounts of fentanyl and its analogs.

Rapid deep learning-assisted predictive diagnostics for point-of-care testing

Prominent techniques such as real-time polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), and rapid kits are currently being explored to both enhance sensitivity and reduce assay time for diagnostic tests. Existing commercial molecular methods typically take several hours, while immunoassays can range from several hours to tens of minutes. Rapid diagnostics are crucial in Point-of-Care Testing (POCT). We propose an approach that integrates a time-series deep learning architecture and AI-based verification, for the enhanced result analysis of lateral flow assays. This approach is applicable to both infectious diseases and non-infectious biomarkers. In blind tests using clinical samples, our method achieved diagnostic times as short as 2 minutes, exceeding the accuracy of human analysis at 15 minutes. Furthermore, our technique significantly reduces assay time to just 1-2 minutes in the POCT setting. This advancement has the potential to greatly enhance POCT diagnostics, enabling both healthcare professionals and non-experts to make rapid, accurate decisions.

Stepwise Au decoration-assisted double signal amplified lateral flow strip for ultrasensitive detection of morphine in fingerprint sweat

Point-of-care testing (POCT) of morphine (MOP) without invasion of privacy is of critical importance for law-enforcement departments to realize on-site rapid screening. In this study, ultrasensitive and non-invasive screening of MOP residues in the fingerprint sweat was easily realized by stepwise Au decoration-assisted double signal amplification and antibody-saving strategies on lateral flow strip (LFS). The construction of LFS was not intrinsically changed compared with traditional LFS except the labeling material on conjugation pad for enhanced signal reporting. The gold nanoparticle-seeded SiO2 was adopted as the labeling materials in place of traditional gold nanoparticles, which acted as the first-round signal amplification and ready for second-round gold deposition-assisted amplification. And the second-round amplification could be completed in just 10 s, which did not alter the intrinsic simplicity of LFS for rapid and on-site screening. With the designed signal amplification principle of LFS, target MOP in the fingerprint sweat can be effectively transferred to the LFS for analysis without invasion of privacy. As low as 0.5 pg MOP in fingerprint sweat can be visually judged with this double signal amplified LFS, the sensitivity of which has been improved at least 10-fold compared with traditional Au-labeled LFS, guaranteeing accurate screening of trace MOP in the fingerprint sweat. Of great importance, the consumption of valuable antibody can be reduced to just 1/20, which greatly reduces the cost of high-throughput screening. This stepwise Au decoration-assisted double signal amplified LFS holds great potential in the ultrasensitive screening of trace analytes in various fields and further widens the application scope of lateral flow strips.

A Highly Sensitive and Specific Photonic Crystal-Based Opioid Sensor with Rapid Regeneration

Opioid misuse and overdose have caused devastating public health challenges and economic burdens, calling for the need of rapid, accurate sensitive opioid sensors. Here, we report a photonic crystal-based opioid sensor in the total internal reflection configuration, providing label-free, rapid, quantitative measurements through change of the refractive index. The one-dimensional photonic crystal with a defect layer that is immobilized with opioid antibodies acts as a resonator with an open microcavity. The highly accessible structure responds to analytes within a minute after the aqueous opioid solution is introduced, achieving the highest sensitivity of 5688.8 nm/refractive index unit (RIU) at the incident angle of 63.03°. Our sensor shows a limit of detection (LOD) of 7 ng/mL for morphine in phosphate-buffered saline (PBS, pH 7.4) solutions, well below the required clinical detection limit, and an LOD of 6 ng/mL for fentanyl in PBS, close to the clinical requirement. The sensor can selectively detect fentanyl from a mixture of morphine and fentanyl and be regenerated in 2 min with up to 93.66% recovery rate after five cycles. The efficacy of our sensor is further validated in artificial interstitial fluid and human urine samples.

Using Machine Learning to Predict Treatment Adherence in Patients on Medication for Opioid Use Disorder

OBJECTIVE

Patients receiving medication for opioid use disorder (MOUD) may continue using nonprescribed drugs or have trouble with medication adherence, and it is difficult to predict which patients will continue to do so. In this study, we develop and validate an automated risk-modeling framework to predict opioid abstinence and medication adherence at a patient's next attended appointment and evaluate the predictive performance of machine-learning algorithms versus logistic regression.

METHODS

Urine drug screen and attendance records from 40,005 appointments drawn from 2742 patients at a multilocation office-based MOUD program were used to train logistic regression, logistic ridge regression, and XGBoost models to predict a composite indicator of treatment adherence (opioid-negative and norbuprenorphine-positive urine, no evidence of urine adulteration) at next attended appointment.

RESULTS

The XGBoost model had similar accuracy and discriminative ability (accuracy, 88%; area under the receiver operating curve, 0.87) to the two logistic regression models (accuracy, 88%; area under the receiver operating curve, 0.87). The XGBoost model had nearly perfect calibration in independent validation data; the logistic and ridge regression models slightly overestimated adherence likelihood. Historical treatment adherence, attendance rate, and fentanyl-positive urine at current appointment were the strongest contributors to treatment adherence at next attended appointment.

DISCUSSION

There is a need for risk prediction tools to improve delivery of MOUD. This study presents an automated and portable risk-modeling framework to predict treatment adherence at each patient's next attended appointment. The XGBoost algorithm appears to provide similar classification accuracy to logistic regression models; however, XGBoost may offer improved calibration of risk estimates compared with logistic regression.

Highly Sensitive Fentanyl Detection Based on Nanoporous Electrochemical Immunosensors

Rapid and accurate detection of fentanyl (highly potent opioid) is a critical importance due to current opioids crisis worldwide. We report the highly sensitive detection of fentanyl utilizing the synergetic effect of nanoporous silicon as a substrate with a high interfacial area and specific antibody functionalization of nanoporous silicon. The electrochemical sensor consists of gold working and counter electrodes deposited on nanoprous silicon, antibodies immobilized between these electrodes and an Ag/AgCl reference electrode. Square wave voltammetry was used as an electrochemical transduction method. The detection limit was determined as 6 ng/ml and 11.5 ng/ml for specific peak (fentanyl signature) in phosphate buffer and human sweat, respectively. A future goal of this study is to a wearable sweat sensor array for rapid and on-site detection of multiple opioids with analytical sensitivity comparable with laboratory tests.

Normalizing the Optical Signal Enables Robust Assays with Lateral Flow Biosensors

Lateral flow assays (LFAs) are widely adopted for fast, on-site molecular diagnostics. Obtaining high-precision assay results, however, remains challenging and often requires a dedicated optical setup to control the imaging environment. Here, we describe quick light normalization exam (qLiNE) that transforms ubiquitous smartphones into a robust LFA reader. qLiNE used a reference card, printed with geometric patterns and color standards, for real-time optical calibration: a photo of an LFA test strip was taken along with the card, and the image was processed using a smartphone app to correct shape distortion, illumination brightness, and color imbalances. This approach yielded consistent optical signal, enabling quantitative molecular analyses under different illumination conditions. We adapted qLiNE to detect cortisol, a known stress hormone, in saliva samples at point-of-use settings. The assay was fast (15 min) and sensitive (detection limit, 0.16 ng/mL). The serial qLiNE assay detected diurnal cycles of cortisol levels as well as stress-induced cortisol increase.

Endogenous opiates and behavior: 2020

This paper is the forty-third consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2020 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

The North American opioid epidemic: opportunities and challenges for clinical laboratories

Since 1999, the opioid epidemic in North America has resulted in over 1 million deaths, and it continues to escalate despite numerous efforts in various arenas to combat the upward trend. Clinical laboratories provide drug testing to support practices such as emergency medicine, substance use disorder treatment, and pain management; increasingly, these laboratories are collaborating in novel partnerships including drug-checking services (DCS) and multidisciplinary treatment teams. This review examines drug testing related to management of licit and illicit opioid use, new technologies and test strategies employed by clinical laboratories, barriers hindering laboratory response to the opioid epidemic, and areas for improvement and standardization within drug testing. Literature search terms included combinations of "opioid," "opiate," "fentanyl," "laboratory," "epidemic," "crisis," "mass spectrometry," "immunoassay," "drug screen," "drug test," "guidelines," plus review of PubMed "similar articles" and references within publications. While immunoassay (IA) and point-of-care (POC) test options for synthetic opioids are increasingly available, mass spectrometry (MS) platforms offer the greatest flexibility and sensitivity for detecting novel, potent opioids. Previously reserved as a second-tier application in most drug test algorithms, MS assays are gaining a larger role in initial screening for specific patients and DCS. However, there are substantial differences among laboratories in terms of updating test menus, algorithms, and technologies to meet changing clinical needs. While some clinical laboratories lack the resources and expertise to implement MS, many are also slow to adopt available IA and POC tests for newer opioids such as fentanyl. MS-based testing also presents challenges, including gaps in available guidance for assay validation and ongoing performance assessment that contribute to a dramatic lack of standardization among laboratories. We identify opportunities for improvement in laboratory operations, reporting, and interpretation of drug test results, including laboratorian and provider education and laboratory-focused guidelines. We also highlight the need for collaboration with providers, assay and instrument manufacturers, and national organizations to increase the effectiveness of clinical laboratory and provider efforts in preventing morbidity and mortality associated with opioid use and misuse.

False-positive fentanyl screening kit results during treatment with long term injectable risperidone (Risperdal-Consta)

Fentanyl, a highly potent synthetic opioid, is a major cause of overdose deaths in the United States and worldwide. Urine drug immunoassay tests that include fentanyl in their drug panel are the common screening tool. However, false positive results may compromise test accuracy and cause grave clinical outcomes. In this preliminary report we describe 3 cases of patients with schizophrenia, who are treated with long-term injectable risperidone (Risperdal Consta) and were false positively screened for fentanyl by a rapid commercial screening kit. This finding warrants clinical attention to the possibility of inaccurate results regarding fentanyl misuse in multiple clinical settings.

Monoclonal Antibodies Application in Lateral Flow Immunochromatographic Assays for Drugs of Abuse Detection

Lateral flow assays (lateral flow immunoassays and nucleic acid lateral flow assays) have experienced a great boom in a wide variety of early diagnostic and screening applications. As opposed to conventional examinations (High Performance Liquid Chromatography, Polymerase Chain Reaction, Gas chromatography-Mass Spectrometry, etc.), they obtain the results of a sample's analysis within a short period. In resource-limited areas, these tests must be simple, reliable, and inexpensive. In this review, we outline the production process of antibodies against drugs of abuse (such as heroin, amphetamine, benzodiazepines, cannabis, etc.), used in lateral flow immunoassays as revelation or detection molecules, with a focus on the components, the principles, the formats, and the mechanisms of reaction of these assays. Further, we report the monoclonal antibody advantages over the polyclonal ones used against drugs of abuse. The perspective on aptamer use for lateral flow assay development was also discussed as a possible alternative to antibodies in view of improving the limit of detection, sensitivity, and specificity of lateral flow assays.

Point-of-Care Drug of Abuse Testing in the Opioid Epidemic

CONTEXT.—

The United States is experiencing an opioid overdose epidemic. Point-of-care (POC) drug of abuse testing is a useful tool to combat the intensified opioid epidemic.

OBJECTIVES.—

To review commercially available POC drug of abuse testing involving opioids, to review opportunities and challenges for POC opioid testing and emerging testing methods in research literature, and finally to summarize unmet clinical needs and future development prospects.

DATA SOURCES.—

The Google search engine was used to access information for commercial opioid POC devices and the Google Scholar search engine was used to access research literature published from 2000 to 2019 for opioid POC tests.

CONCLUSIONS.—

The opioid epidemic provides unprecedented opportunities for POC drug testing, with significant clinical needs. Compared with gold standard tests, limitations for commercially available opioid POC testing include lower analytical sensitivity, lower specificity, and cross-reactivity. In response to unmet clinical needs, novel methods have emerged in research literature, such as microfluidics and miniature mass spectrometry. Future prospects include the development of quantitative POC devices and smarter and real-time drug testing.

Tutorial: design and fabrication of nanoparticle-based lateral-flow immunoassays

Lateral-flow assays (LFAs) are quick, simple and cheap assays to analyze various samples at the point of care or in the field, making them one of the most widespread biosensors currently available. They have been successfully employed for the detection of a myriad of different targets (ranging from atoms up to whole cells) in all type of samples (including water, blood, foodstuff and environmental samples). Their operation relies on the capillary flow of the sample throughout a series of sequential pads, each with different functionalities aiming to generate a signal to indicate the absence/presence (and, in some cases, the concentration) of the analyte of interest. To have a user-friendly operation, their development requires the optimization of multiple, interconnected parameters that may overwhelm new developers. In this tutorial, we provide the readers with: (i) the basic knowledge to understand the principles governing an LFA and to take informed decisions during lateral flow strip design and fabrication, (ii) a roadmap for optimal LFA development independent of the specific application, (iii) a step-by-step example procedure for the assembly and operation of an LF strip for the detection of human IgG and (iv) an extensive troubleshooting section addressing the most frequent issues in designing, assembling and using LFAs. By changing only the receptors, the provided example procedure can easily be adapted for cost-efficient detection of a broad variety of targets.