Nanoparticle-modified microrobots for in vivo antibiotic delivery to treat acute bacterial pneumonia.

Bioinspired microrobots capable of actively moving in biological fluids have attracted considerable attention for biomedical applications because of their unique dynamic features that are otherwise difficult to achieve by their static counterparts. Here we use click chemistry to attach antibiotic-loaded neutrophil membrane-coated polymeric nanoparticles to natural microalgae, thus creating hybrid microrobots for the active delivery of antibiotics in the lungs in vivo. The microrobots show fast speed (>110 µm s-1) in simulated lung fluid and uniform distribution into deep lung tissues, low clearance by alveolar macrophages and superb tissue retention time (>2 days) after intratracheal administration to test animals. In a mouse model of acute Pseudomonas aeruginosa pneumonia, the microrobots effectively reduce bacterial burden and substantially lessen animal mortality, with negligible toxicity. Overall, these findings highlight the attractive functions of algae-nanoparticle hybrid microrobots for the active in vivo delivery of therapeutics to the lungs in intensive care unit settings.

Acoustic Nanomotors for Detection of Human Papillomavirus-Associated Head and Neck Cancer.

OBJECTIVE: Human papillomavirus (HPV)-associated oropharyngeal cancer (OPC) is a lethal disease with increasing incidence; however, technologies for early detection are limited. Nanomotors are synthetic nanostructures that can be powered by different mechanisms and functionalized for specific applications, such as biosensing. The objective of this investigation was to demonstrate an in vitro proof of concept for a novel nanomotor-based cancer detection approach toward in vivo detection of HPV-OPC. STUDY DESIGN: In vitro cell line incubated with ultrasound-propelled nanomotors. SETTING: Basic science and engineering laboratories. SUBJECTS AND METHODS: Ultrasound-powered gold nanowire nanomotors were functionalized with graphene oxide and dye-labeled single-stranded DNA for the specific intracellular detection of HPV16 E6 mRNA transcripts. Nanomotors were incubated with HPV-positive or HPV-negative human OPC cells under static conditions or with an applied ultrasound field for 15 minutes. The resulting intracellular fluorescence was assessed with fluorescence microscopy and analysis software. RESULTS: Nanomotors incubated with RNA extracted from HPV-positive OPC cells resulted in 60.7% of maximal fluorescence recovery, while incubation with RNA extracted from HPV-negative cells produced negligible fluorescence. Nanomotor incubation with intact HPV-negative cells produced minimal fluorescence (0.01 au), while incubation with HPV-positive cells produced a detectable signal (0.43 au) under static conditions and had 2.3-times greater intensity when powered with ultrasound. CONCLUSION: Acoustically powered nanomotors can successfully identify HPV16 E6 mRNA transcripts extracellularly and within intact cells. This work represents the first step toward a novel, practical approach to address the challenge of visually detecting HPV-OPC in real time.

Wearable biosensors for healthcare monitoring.

Wearable biosensors are garnering substantial interest due to their potential to provide continuous, real-time physiological information via dynamic, noninvasive measurements of biochemical markers in biofluids, such as sweat, tears, saliva and interstitial fluid. Recent developments have focused on electrochemical and optical biosensors, together with advances in the noninvasive monitoring of biomarkers including metabolites, bacteria and hormones. A combination of multiplexed biosensing, microfluidic sampling and transport systems have been integrated, miniaturized and combined with flexible materials for improved wearability and ease of operation. Although wearable biosensors hold promise, a better understanding of the correlations between analyte concentrations in the blood and noninvasive biofluids is needed to improve reliability. An expanded set of on-body bioaffinity assays and more sensing strategies are needed to make more biomarkers accessible to monitoring. Large-cohort validation studies of wearable biosensor performance will be needed to underpin clinical acceptance. Accurate and reliable real-time sensing of physiological information using wearable biosensor technologies would have a broad impact on our daily lives.

Active Intracellular Delivery of a Cas9/sgRNA Complex Using Ultrasound-Propelled Nanomotors.

Direct and rapid intracellular delivery of a functional Cas9/sgRNA complex using ultrasound-powered nanomotors is reported. The Cas9/sgRNA complex is loaded onto the nanomotor surface through a reversible disulfide linkage. A 5 min ultrasound treatment enables the Cas9/sgRNA-loaded nanomotors to directly penetrate through the plasma membrane of GFP-expressing B16F10 cells. The Cas9/sgRNA is released inside the cells to achieve highly effective GFP gene knockout. The acoustic Cas9/sgRNA-loaded nanomotors display more than 80 % GFP knockout within 2 h of cell incubation compared to 30 % knockout using static nanowires. More impressively, the nanomotors enable highly efficient knockout with just 0.6 nm of the Cas9/sgRNA complex. This nanomotor-based intracellular delivery method thus offers an attractive route to overcome physiological barriers for intracellular delivery of functional proteins and RNAs, thus indicating considerable promise for highly efficient therapeutic applications.

Targeting and isolation of cancer cells using micro/nanomotors.

Micro/nanomotors distinguish themselves with in situ energy conversion capability for autonomous movement, a feature that confers remarkable potential to improve cancer treatment. In this review article, three areas are highlighted where micro/nanomotors have established themselves with unique contributions, including propelled navigation to promote cancer cell targeting, powered cell membrane penetration to enhance intracellular delivery, and steered isolation of circulating tumor cells for detection. Progress made in these areas has offered promising inspiration and opportunities aimed for enhancing the efficiency and precision of drug targeting to cancer cells, improving the capability of delivering anticancer drug into cytoplasm for bioactivity, and enabling more rapid and sensitive cancer cell detection. Herein, we review each area with highlights of the current and forthcoming micro/nanomotor techniques in advancing cancer diagnosis and treatment.

Author correction: Micromotor-enabled active drug delivery for in vivo treatment of stomach infection.

Marygorret Obonyo, who provided the H. pylori SS1 strain for this work and participated in the design of H. pylori infection studies, was inadvertently omitted from the author list. This has now been corrected in both the PDF and HTML versions of the Article.

Micromotor-enabled active drug delivery for in vivo treatment of stomach infection.

Advances in bioinspired design principles and nanomaterials have led to tremendous progress in autonomously moving synthetic nano/micromotors with diverse functionalities in different environments. However, a significant gap remains in moving nano/micromotors from test tubes to living organisms for treating diseases with high efficacy. Here we present the first, to our knowledge, in vivo therapeutic micromotors application for active drug delivery to treat gastric bacterial infection in a mouse model using clarithromycin as a model antibiotic and Helicobacter pylori infection as a model disease. The propulsion of drug-loaded magnesium micromotors in gastric media enables effective antibiotic delivery, leading to significant bacteria burden reduction in the mouse stomach compared with passive drug carriers, with no apparent toxicity. Moreover, while the drug-loaded micromotors reach similar therapeutic efficacy as the positive control of free drug plus proton pump inhibitor, the micromotors can function without proton pump inhibitors because of their built-in proton depletion function associated with their locomotion.Nano- and micromotors have been demonstrated in vitro for a range of applications. Here the authors demonstrate the in-vivo therapeutic use of micromotors to treat H. pylori infection.

Rapid micromotor-based naked-eye immunoassay.

A dynamic micromotor-based immunoassay, exemplified by cortisol detection, based on the use of tubular micromotors functionalized with a specific antibody is described. The use of antibody-functionalized micromotors offers huge acceleration of both direct and competitive cortisol immunoassays, along with greatly enhanced sensitivity of direct and competitive immunoassays. The dramatically improved speed and sensitivity reflect the greatly increased likelihood of antibody-cortisol contacts and fluid mixing associated with the dynamic movement of these microtube motors and corresponding bubble generation that lead to a highly efficient and rapid recognition process. Rapid naked-eye detection of cortisol in the sample is achieved in connection to use of horseradish peroxidase (HRP) tag and TMB/H2O2 system. Key parameters of the competitive immunoassay (e.g., incubation time and reaction volume) were optimized. This fast visual micromotor-based sensing approach enables "on the move" specific detection of the target cortisol down to 0.1µgmL-1 in just 2min, using ultrasmall (50µL) sample volumes.

Disposable amperometric magnetoimmunosensor for the sensitive detection of the cardiac biomarker amino-terminal pro-B-type natriuretic peptide in human serum.

A novel amperometric magnetoimmunosensor using an indirect competitive format is developed for the sensitive detection of the amino-terminal pro-B-type natriuretic peptide (NT-proBNP). The immunosensor design involves the covalent immobilization of the antigen onto carboxylic-modified magnetic beads (HOOC-MBs) activated with N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) and N-hydroxysulfosuccinimide (sulfo-NHS), and further incubation in a mixture solution containing variable concentrations of the antigen and a fixed concentration of an HRP-labeled detection antibody. Accordingly, the target NT-proBNP in the sample and that immobilized on the MBs compete for binding to a fixed amount of the specific HRP-labeled secondary antibody. The immunoconjugate-bearing MBs are captured by a magnet placed under the surface of a disposable gold screen-printed electrode (Au/SPE). The amperometric responses measured at -0.10 V (vs. a Ag pseudo-reference electrode), upon addition of 3,3',5,5'-tetramethylbenzidine (TMB) as electron transfer mediator and H2O2 as the enzyme substrate, are used to monitor the affinity reaction. The developed magnetoimmunosensor provides attractive analytical characteristics in 10-times diluted human serum samples, exhibiting a linear range of clinical usefulness (0.12-42.9 ng mL(-1)) and a detection limit of 0.02 ng mL(-1), which can be used in clinical diagnosis of chronic heart failure in the elderly and for classifying patients at risk of death after heart transplantation. The magnetoimmunosensor was successfully applied to the analysis of spiked human serum samples.

Disposable amperometric magnetoimmunosensors for the specific detection of Streptococcus pneumoniae.

Disposable amperometric magnetoimmunosensors, based on the use of functionalized magnetic beads and gold screen-printed electrodes, have been developed for the selective detection and quantification of Streptococcus pneumoniae. A specific antibody prepared against a serotype 37 S. pneumoniae strain, selected by flow cytometry among seven anticapsular or antisomatic antibodies, was linked to Protein A-modified magnetic beads and incubated with bacteria. The same antibody, conjugated with horseradish peroxidase, was attached to the bacteria and the resulting modified magnetic beads were captured by a magnetic field on the surface of tetrathiafulvalene-modified gold screen-printed electrodes. The amperometric response obtained at -0.15 V vs. the silver pseudoreference electrode of the Au/SPE after the addition of H(2)O(2) was used as transduction signal. Different assay formats were examined and the experimental variables optimized. The limits of detection achieved, without pre-concentration or pre-enrichment steps, were 1.5×10(4) cfu mL(-1) (colony forming unit) and 6.3×10(5) cfu mL(-1) for S. pneumoniae strains Dawn (serotype 37) and R6 (non-encapsulated), respectively. The developed methodology shows a good selectivity against closely related streptococci and its usefulness for the analysis of inoculated urine samples has been demonstrated. The total analysis time of 3.5 h from sampling to measurement, the possibility to prepare up to 30 sensors per day and the use of small amounts of test solution for S. pneumoniae identification, constitute important advantages that make the developed methodology a promising alternative for clinical diagnosis.