Application of programmable bio-nano-chip system for the quantitative detection of drugs of abuse in oral fluids

Highlights

• First application of p-BNC technology for the detection of drugs of abuse in oral fluids..

• Rapid (∼10 min), sensitive detection (∼ng/mL) and quantitation of 12 drugs of abuse was demonstrated on the p-BNC platform.

• Demonstration of simultaneous detection and measurement of multiple drugs.

• Strong correlation of p-BNC test against reference method.

• P-BNC quantitate drugs of abuse and reveal their time-course in oral fluids with potential to elucidate level of impairment.

Abstract

Objective

There is currently a gap in on-site drug of abuse monitoring. Current detection methods involve invasive sampling of blood and urine specimens, or collection of oral fluid, followed by qualitative screening tests using immunochromatographic cartridges. While remote laboratories then may provide confirmation and quantitative assessment of a presumptive positive, this instrumentation is expensive and decoupled from the initial sampling making the current drug-screening program inefficient and costly. The authors applied a noninvasive oral fluid sampling approach integrated with the in-development chip-based Programmable bio-nano-chip (p-BNC) platform for the detection of drugs of abuse.

Method

The p-BNC assay methodology was applied for the detection of tetrahydrocannabinol, morphine, amphetamine, methamphetamine, cocaine, methadone and benzodiazepines, initially using spiked buffered samples and, ultimately, using oral fluid specimen collected from consented volunteers.

Results

Rapid (∼10 min), sensitive detection (∼ng/mL) and quantitation of 12 drugs of abuse was demonstrated on the p-BNC platform. Furthermore, the system provided visibility to time-course of select drug and metabolite profiles in oral fluids; for the drug cocaine, three regions of slope were observed that, when combined with concentration measurements from this and prior impairment studies, information about cocaine-induced impairment may be revealed.

Conclusions

This chip-based p-BNC detection modality has significant potential to be used in the future by law enforcement officers for roadside drug testing and to serve a variety of other settings, including outpatient and inpatient drug rehabilitation centers, emergency rooms, prisons, schools, and in the workplace.

Introduction

Driving under the influence of drugs is a problem of growing concern in many countries, including the United States (US) and the United Kingdom (UK). In spite of the most stringent drug policies and punitive laws, in 2008 the US had the highest levels of lifetime illegal cocaine and marijuana use, with these and other drugs and their metabolites being increasingly detected in impaired and injured automobile drivers (http://oas.samhsa.gov/nsduh.htm). Drug use is a contributory factor to a significant percentage of fatal road traffic collisions. In the UK, in 2010/2011, an estimated 19% of adult drivers who had taken illegal drugs reported driving at least once or twice within the last 12 months while they were affected by or under the influence of illegal drugs (http://assets.dft.gov.uk/statistics/releases/road-accidents-and-safety-annual-report-2011/rrcgb2011-05.pdf).

Despite these dire facts, neither the US nor UK, nor any other country for that matter, has access to a reliable method analogous to the alcohol breath-alyzer to detect drugged-drivers. Likewise, practical limitations associated with the current sampling approaches to collect forensic specimens, as well as lack of suitable technologies that could efficiently, accurately and sensitively determine drug concentrations outside of the laboratory setting have hindered progress in this area.

Current approaches involve blood sampling, which is invasive, and requires specialized sample collection and preparatory work prior to sample analysis. This process is time-consuming and, in most cases, confined to a laboratory setting. In some situations urine sampling is a better alternative, but associated with privacy issues, concerns with chain of custody and vulnerability to adulteration. Hence, there is a pressing need for alternative diagnostic fluids/matrices, such as hair, sweat and oral fluids for drug testing.

Indeed, in recent reviews saliva is presented as a clinically informative biological fluid that is increasingly shown to be useful for prognosis, laboratory or clinical diagnosis, and monitoring and management of patients with both oral and systemic diseases (Malamud and Rodriguez-Chavez, 2011, Lee et al., 2009, Wong, 2008, Parisi et al., 2009, White et al., 2009).

Oral fluid-based immunochromatographic strip (ICS) tests have been developed with capabilities in various drug testing/screening settings outside the laboratory (Crouch et al., 2008, Vanstechelman et al., 2012). However, these tests are not quantitative, thereby limiting access to potential impairment status, as well as they exhibit only restricted multiplexed capabilities, making them less practical for point-of-need settings (Bosker and Huestis, 2009).

The marriage of noninvasive sampling with portable detection capabilities afforded with lab-on-a-chip systems provides an ideal opportunity to address unmet needs for the drug testing and monitoring areas. Over the past two decades much progress has been made in the direction of development of new chip-based systems. Indeed, pioneering work by Whitesides in the basic sciences defined the ideal coatings, materials and designs for the development of microfluidic channels and manipulations of biological fluids (Whitesides, 2006), while Quake's group advanced the ‘large-scale integration’ of microfluidics, analogous to the electronics field (Thorsen et al., 2002). Other groups, such as those of Mirkin, Wang and Heath, measured diverse sample types and created a variety of assembly types by using precious metal nanoparticles, nanowires, and magnetic techniques, respectively (Goluch et al., 2006, Osterfield et al., 2008, Qin et al., 2009). Advancements by Sia via micro-electromechanical systems and Singh using chip-based separation and quantitation benefited integration of such systems (Srivastava et al., 2009, Chin et al., 2007). Both Singh and Ligler have extended their integrated approaches into the rapid, multiplexed detection of analytes, such as toxins and other bio-threats (Kim et al., 2009), while Walt's work with electronic noses used arrays of optical fibers as the underlying infrastructure for biological sensing systems (Walt, 2005). Finally, researchers in the Toner group have explored a number of novel methods for the isolation and enumeration of lymphocytes, erythrocytes and circulating tumor cells (Cheng et al., 2009, Maheswaran et al., 2008). While such chip-based detection modalities have strong potential for use in clinical and sensor applications, the development of fully integrated and clinically validated structures remains a significant barrier for these structures, including for those intended for drug testing point-of-need applications (Bell and Hanes, 2007, Bruls et al., 2009, Qiang et al., 2009, Zhou et al., 2012). In the area of oral fluid testing, additional challenges are presented with respect to the management and processing of oral fluid samples due to the high viscosity and complex nature of such specimens.

The purpose of this article is to describe recent work that is leading to the development of new oral fluid detection capabilities, whereby multiple drug and metabolites can be detected and quantitated using Programmable bio-nano-chips (p-BNCs; Christodoulides et al., 2002, Christodoulides et al., 2012, Floriano et al., 2009, Goodey et al., 2001, Raamanathan et al., 2012, Rodriguez et al., 2005). These efforts place into the pipeline new options for drug testing that have significant potential to influence measurement of drug samples for a wide variety of settings.