Hybrid Graphene-Metallic Optofluidic Nanostructures for the Point-of-Care Detection of Illicit Drugs and Biological Agents

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There is a timely need in Canada for sensing technologies that allow ultrasensitive, rapid and in situ detection of chemical and biological agents such as bioterrorism agents, explosives, or illicit drugs and pathogenic bacteria in bodily fluids. There is no commercial technol¬ogy capable of detecting those analytes, in situ, and in timely fashion. Current detection technologies require costly and labor-intensive procedures that prevent potential users, such as law enforcement officers, (para)medics or soldiers, to perform detection at the point of use. Metallic nanostructures that support surface plasmons, such as metallic nanohole arrays, have demonstrated to be great contenders as biosensors, holding distinct merits for the label-free detection of bio-molecular interactions. We have very recently developed optofluidic nanostructured sensors based on metallic flow-through nanoholes, that enable the detection of ovarian cancer biomarkers and uropathogenic E. coli in humane urine - the bacteria responsible for urinary tract infections (UTI) - at concentrations below the clinical threshold for UTI diagnosis. Despite their potential as biosensors, three major obstacles limit the performance of optofluidic nanostructures as biosensor: (i) poor mechanical stability in flow-through operation, (ii) the use of metals with subpar photonic characteristics to build the nanostructures, and (iii) their operation is limited to the visible range of the spectrum. Recent scientific breakthroughs, published in Science and Nature Photonics, have demonstrated that graphene can support surface plasmons at mid-infrared and THz frequencies. In addition, graphene also owns outstanding mechanical properties. The proposed research aims to develop a new generation of hybrid graphene-metallic nanostructured biosensors with superior properties in terms of performance and sensitivity, through three distinct objectives: (1) the exploration and development of hybrid graphene-metallic optofluidic nanostructured (bio)sensors; (2) investigation of structure-performance relations that correlate key optical and mechanical characteristics of the nanostructures with consequential sensitivity in flow-through conditions; and (3) investigate the utilization of N-heterocyclic carbenes as functionalization agents to achieve detection of bacteria in acidic pH media (pH < 2) and illicit drugs (i.e. opioids). These sensors will advance the state-of-the-art by providing the following advantages: (a) the use of metals with superior photonic properties (other than gold); (b) better mechanical stability and operation at THz frequencies; and (c) enhanced sensitivity by facilitating the active concentration of analyte, such as charged molecules, proteins and bacteria. The program will train 3 PhD, 3 MSc and 4 undergraduate students, who will acquire theoretical, experimental and computational modelling skills used in the (bio)sensing, medical diagnostics and analytical chemistry R&D industry.