Label-Free Porous Silicon Immunosensor for Broad Detection of Opiates in a Blind Clinical Study and Results Comparison to Commercial Analytical Chemistry Techniques

Abstract

In this work we evaluate for the first time the performance of a label-free porous silicon (PSi) immunosensor assay in a blind clinical study designed to screen authentic patient urine specimens for a broad range of opiates. The PSi opiate immunosensor achieved 96% concordance with liquid chromatography-mass spectrometry/tandem mass spectrometry (LC-MS/MS) results on samples that underwent standard opiate testing (n=50). In addition, successful detection of a commonly abused opiate, oxycodone, resulted in 100% qualitative agreement between the PSi opiate sensor and LC-MS/MS. In contrast, a commercial broad opiate immunoassay technique (CEDIA ® ) achieved 65% qualitative concordance with LC-MS/MS. Evaluation of important performance attributes including precision, accuracy, and recovery was completed on blank urine specimens spiked with test analytes. Variability of morphine detection as a model opiate target was < 9% both within-run and between-day at and above the cutoff limit of 300 ng ml −1 . This study validates the analytical screening capability of label-free PSi opiate immunosensors in authentic patient samples and is the first semi-quantitative demonstration of the technology's successful clinical use. These results motivate future development of PSi technology to reduce complexity and cost of diagnostic testing particularly in a point-of-care setting.

Chemical stabilization of porous silicon for enhanced biofunctionalization with immunoglobulin

“…This result indicates that the Cox preserves the porosity of the PSi layer, keeping its internal surface available for the biomolecule attachment. By exploiting this optical shift, PSi devices can be used as label-free optical biosensing systems [16,31,32].…”

Advances in Porous Silicon–Based Nanomaterials for Diagnostic and Therapeutic Applications

“…The specific nature of the antibody–antigen interaction can be exploited to generate a measurable optical signal in an interferometric pSi biosensor. Interferometric immunosensors based on a range of pSi photonic crystal structures have been demonstrated for the detection of a variety of analytes of biomedical interest, including opiates, bacteria, and human immunoglobulin G (IgG) . Significant research efforts have been devoted to optimizing the analyte diffusion into the pores, the immobilization chemistry, the signal processing, or the photonic crystal preparation in order to achieve the sufficient sensitivity for real clinical diagnosis.…”

Porous Silicon Optical Devices: Recent Advances in Biosensing Applications

“…The free drugs, contained in urine samples and analogues, bound to the matrix, competed for the binding site of the antibodies. An indirect methodology was used to detect the free drug, measuring an LoD of 0.018 µM and making the platform appealing for POC applications [ 137 , 138 ].…”