title: Integrated electrochemical microsystems for genetic detection of pathogens at the point of care.
abstract: The capacity to achieve rapid, sensitive, specific, quantitative, and multiplexed genetic detection of pathogens via a robust, portable, point-of-care platform could transform many diagnostic applications. And while contemporary technologies have yet to effectively achieve this goal, the advent of microfluidics provides a potentially viable approach to this end by enabling the integration of sophisticated multistep biochemical assays (e.g., sample preparation, genetic amplification, and quantitative detection) in a monolithic, portable device from relatively small biological samples. Integrated electrochemical sensors offer a particularly promising solution to genetic detection because they do not require optical instrumentation and are readily compatible with both integrated circuit and microfluidic technologies. Nevertheless, the development of generalizable microfluidic electrochemical platforms that integrate sample preparation and amplification as well as quantitative and multiplexed detection remains a challenging and unsolved technical problem. Recognizing this unmet need, we have developed a series of microfluidic electrochemical DNA sensors that have progressively evolved to encompass each of these critical functionalities. For DNA detection, our platforms employ label-free, single-step, and sequence-specific electrochemical DNA (E-DNA) sensors, in which an electrode-bound, redox-reporter-modified DNA "probe" generates a current change after undergoing a hybridization-induced conformational change. After successfully integrating E-DNA sensors into a microfluidic chip format, we subsequently incorporated on-chip genetic amplification techniques including polymerase chain reaction (PCR) and loop-mediated isothermal amplification (LAMP) to enable genetic detection at clinically relevant target concentrations. To maximize the potential point-of-care utility of our platforms, we have further integrated sample preparation via immunomagnetic separation, which allowed the detection of influenza virus directly from throat swabs and developed strategies for the multiplexed detection of related bacterial strains from the blood of septic mice. Finally, we developed an alternative electrochemical detection platform based on real-time LAMP, which not is only capable of detecting across a broad dynamic range of target concentrations, but also greatly simplifies quantitative measurement of nucleic acids. These efforts represent considerable progress toward the development of a true sample-in-answer-out platform for genetic detection of pathogens at the point of care. Given the many advantages of these systems, and the growing interest and innovative contributions from researchers in this field, we are optimistic that iterations of these systems will arrive in clinical settings in the foreseeable future.
authors.affiliation: †Department of Mechanical Engineering, ‡Institute for Collaborative Biotechnologies, §Interdepartmental Program in Biomolecular Science and Engineering, ∥Department of Chemistry and Biochemistry, and ⊥Materials Department, University of California, Santa Barbara, Santa Barbara, California 93106, United States.
authors.forename: Kuangwen
authors.initials: K
authors.lastname: Hsieh
authors.affiliation: †Department of Mechanical Engineering, ‡Institute for Collaborative Biotechnologies, §Interdepartmental Program in Biomolecular Science and Engineering, ∥Department of Chemistry and Biochemistry, and ⊥Materials Department, University of California, Santa Barbara, Santa Barbara, California 93106, United States.
authors.forename: B Scott
authors.initials: BS
authors.lastname: Ferguson
authors.affiliation: †Department of Mechanical Engineering, ‡Institute for Collaborative Biotechnologies, §Interdepartmental Program in Biomolecular Science and Engineering, ∥Department of Chemistry and Biochemistry, and ⊥Materials Department, University of California, Santa Barbara, Santa Barbara, California 93106, United States.
authors.forename: Michael
authors.initials: M
authors.lastname: Eisenstein
authors.affiliation: †Department of Mechanical Engineering, ‡Institute for Collaborative Biotechnologies, §Interdepartmental Program in Biomolecular Science and Engineering, ∥Department of Chemistry and Biochemistry, and ⊥Materials Department, University of California, Santa Barbara, Santa Barbara, California 93106, United States.
authors.forename: Kevin W
authors.initials: KW
authors.lastname: Plaxco
authors.affiliation: †Department of Mechanical Engineering, ‡Institute for Collaborative Biotechnologies, §Interdepartmental Program in Biomolecular Science and Engineering, ∥Department of Chemistry and Biochemistry, and ⊥Materials Department, University of California, Santa Barbara, Santa Barbara, California 93106, United States.
authors.forename: H Tom
authors.initials: HT
authors.lastname: Soh
mesh_terms: D000818:Animals; D004269:DNA, Bacterial / Q000235:genetics*; D004279:DNA, Viral / Q000235:genetics*; D055664:Electrochemical Techniques; D004566:Electrodes; D006801:Humans; D046210:Microfluidic Analytical Techniques; D021141:Nucleic Acid Amplification Techniques; D019095:Point-of-Care Systems; D016133:Polymerase Chain Reaction
chemical_list: D004269:DNA, Bacterial; D004279:DNA, Viral