Magnetically guided ultrasound-powered nanowire motors, functionalized with bioreceptors and a drug-loaded polymeric segment, are described for "capture and transport" and drug-delivery processes. These high-performance fuel-free motors display advanced capabilities and functionalities, including magnetic guidance, coordinated aligned movement, cargo towing, capture and isolation of biological targets, drug delivery, and operation in real-life biological and environmental media. The template-prepared three-segment Au-Ni-Au nanowire motors are propelled acoustically by mechanical waves produced by a piezoelectric transducer. An embedded nickel segment facilitates a magnetically guided motion as well as transport of large "cargo" along predetermined trajectories. Substantial improvement in the speed and power is realized by the controlled concavity formation at the end of the motor nanowire using a sphere lithography protocol. Functionalization of the Au segments with lectin and antiprotein A antibody bioreceptors allows capture and transport of E. coli and S. aureus bacteria, respectively. Potential therapeutic applications are illustrated in connection to the addition of a pH-sensitive drug-loaded polymeric (PPy-PSS) segment. The attractive capabilities of these fuel-free acoustically driven functionalized Au-Ni-Au nanowires, along with the simple preparation procedure and minimal adverse effects of ultrasonic waves, make them highly attractive for diverse in vivo biomedical applications.

The transport properties of single-strand DNA probe-modified self-propelling micromachines are exploited for "on-the-fly" hybridization and selective single-step isolation of target nucleic acids from "raw" microliter biological samples (serum, urine, crude E. coli lysate, saliva). The rapid movement of the guided modified microrockets induces fluid convection, which enhances the hybridization efficiency, thus enabling the rapid and selective isolation of nucleic acid targets from untreated samples. The integration of these autonomous microrockets into a lab-on-chip device that provides both nucleic acid isolation and downstream analysis could thus be attractive for diverse applications.

Ultrasound (US)-powered nanowire motors based on nanoporous gold segment are developed for increasing the drug loading capacity. The new highly porous nanomotors are characterized with a tunable pore size, high surface area, and high capacity for the drug payload. These nanowire motors are prepared by template membrane deposition of a silver-gold alloy segment followed by dealloying the silver component. The drug doxorubicin (DOX) is loaded within the nanopores via electrostatic interactions with an anionic polymeric coating. The nanoporous gold structure also facilitates the near-infrared (NIR) light controlled release of the drug through photothermal effects. Ultrasound-driven transport of the loaded drug toward cancer cells followed by NIR-light triggered release is illustrated. The incorporation of the nanoporous gold segment leads to a nearly 20-fold increase in the active surface area compared to common gold nanowire motors. It is envisioned that such US-powered nanomotors could provide a new approach to rapidly and efficiently deliver large therapeutic payloads in a target-specific manner.

A new nanomotor-based target isolation strategy, based on a "built-in" recognition capability, is

Detection of specific DNA sequences in clinical samples is a key goal of studies on DNA biosensors and gene chips. Herein we present a highly sensitive electrochemical genosensor for direct measurements of specific DNA sequences in undiluted and untreated human serum and urine samples. Such genosensing relies on a new ternary interface involving hexanedithiol (HDT) co-immobilized with the thiolated capture probe (SHCP) on gold surfaces, followed by the incorporation of 6-mercapto-1-hexanol (MCH) as diluent. The performance of ternary monolayers prepared with linear dithiols of different lengths was systematically examined, compared and characterized by cyclic voltammetry and electrochemical impedance spectroscopy, with HDT exhibiting the most favorable analytical performance. The new SHCP/HDT+MCH monolayer led to a 80-fold improvement in the signal-to-noise ratio (S/N) for 1 nM target DNA in undiluted human serum over the common SHCP/MCH binary alkanethiol interface, and allowed the direct quantification of the target DNA down to 7 pM (28 amol) and 17 pM (68 amol) in undiluted/ untreated serum and urine, respectively. It also displayed attractive antifouling properties, as indicated from the favorable S/N obtained after a prolonged exposure (24 h) to untreated biological matrices. These attractive features of the SHCP/HDT+MCH sensor interface indicate considerable promise for a wide range of clinical applications.

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Biosensors can deliver the rapid bacterial detection that is needed in many fields including food safety, clinical diagnostics, biosafety and biosecurity. Whole-cell imprinted polymers have the potential to be applied as recognition elements in biosensors for selective bacterial detection. In this paper, we report on the use of 3-aminophenylboronic acid (3-APBA) for the electrochemical fabrication of a cell-imprinted polymer (CIP). The use of a monomer bearing a boronic acid group, with its ability to specifically interact with cis-diol, allowed the formation of a polymeric network presenting both morphological and chemical recognition abilities. A particularly beneficial feature of the proposed approach is the reversibility of the cis-diol-boronic group complex, which facilitates easy release of the captured bacterial cells and subsequent regeneration of the CIP. Staphylococcus epidermidis was used as the model target bacteria for the CIP and electrochemical impedance spectroscopy (EIS) was explored for the label-free detection of the target bacteria. The modified electrodes showed a linear response over the range of 10-10cfu/mL. A selectivity study also showed that the CIP could discriminate its target from non-target bacteria having similar shape. The CIPs had high affinity and specificity for bacterial detection and provided a switchable interface for easy removal of bacterial cell.

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