Healthcare acquired infections are a major human health problem, and are becoming increasingly troublesome with the emergence of drug resistant bacteria. Engineered surfaces that reduce the adhesion, proliferation, and spread of bacteria have promise as a mean of preventing infections and reducing the use of antibiotics. To address this need, we created a flexible plastic wrap that combines a hierarchical wrinkled structure with chemical functionalization to reduce bacterial adhesion, biofilm formation, and the transfer of bacteria through an intermediate surface. These hierarchical wraps were effective for reducing biofilm formation of World Health Organization-designated priority pathogens Gram positive methicillin-resistant Staphylococcus aureus (MRSA) and Gram negative Pseudomonas aeruginosa by 87 and 84%, respectively. In addition, these surfaces remain free of bacteria after being touched by a contaminated surface with Gram negative E. coli. We showed that these properties are the result of broad liquid repellency of the engineered surfaces and the presence of reduced anchor points for bacterial adhesion on the hierarchical structure. Such wraps are fabricated using scalable bottom-up techniques and form an effective cover on a variety of complex objects, making them superior to top-down and substrate-specific surface modification methods.

Photoelectrochemical (PEC) biosensors, with optical biasing and electrochemical readout, are expected to enhance the limit-of-detection of electrochemical biosensors by lowering their background signals. However, when PEC transducers are functionalized with biorecognition layers, their current significantly decreases, which reduces their signal-to-noise ratio and dynamic range. Here, we develop and investigate a wrinkled conductive scaffold for loading photoactive quantum dots into an electrode. The wrinkled photoelectrodes demonstrate an order of magnitude enhancement in the magnitude of the transduced PEC current compared to their planar counterparts. We engineer PEC biosensors by functionalizing the wrinkled photoelectrodes with nucleic acid capture probes. We challenge the sensitivity of the wrinkled and planar biosensors with various concentrations of DNA target and observe a 200 times enhancement in the limit-of-detection for wrinkled versus planar electrodes. In addition to enhanced sensitivity, the wrinkled PEC biosensors are capable of distinguishing between fully complementary and targets with a single base-pair mismatch, demonstrating the suitability of these biosensors for use in clinical diagnostics.

agents, [7-12] or changing the surface charge, wettability, chemical affinity, and hydrophilicity. [13-17] Anticoagulants such as heparin have been widely used as coatings on biomedical devices to overcome these adverse effects. [18] Heparin-coated surfaces typically operate through either the release of heparin into the bloodstream for inhibiting clotting in the vicinity of the device surface or reducing coagulation via immobilized heparin on the surface of the device. Anticoagulant coatings fail over time due to leaching and the loss of anticoagulant activity. Furthermore, the administration of anticoagulants (e.g., heparin) both as a coating and a chronic medication, enters the bloodstream, elevating the risk of life-threatening heparin-induced thrombocytopenia, reported to occur in 1-5% of surgical patients. [19] Recently, omniphobic coatings have been introduced on the surface of biomedical devices for reducing biofouling and the resultant blood coagulation, [20-29] while minimizing the administration of anticoagulants. [30] Liquid-infused surfaces are one of the recent classes of omniphobic surfaces which have shown to significantly suppress biofouling and thrombosis with their performances surpassing previous anticoagulant based strategies in terms of longevity under blood flow and anti-biofouling ability. [20-25,27-30] However, in order for these surfaces to sustain their omniphobic and repellent properties, the lubricant layer must be stable on the surfaces, making them difficult to use in open-air applications where the lubricant is susceptible to evaporation. [31] Another class of omniphobic surfaces is those with structural modifications wherein the micro-and nano-scale topography of the surface provides omniphobic properties. Through the formation of micro, nano, and hierarchical structures, air pockets are trapped within the features, leading to the formation of a Cassie wetting state, which reduces the apparent surface energy seen by liquids, [32] resulting in elevated contact angles (CA) and low sliding angles (SA) which lead to omniphobicity. [32] Additionally, the formation of the Cassie state reduces the effective surface area to which platelets and proteins in the blood can bind to, and decreases shear stress at the surfaces reducing platelet adhesion. These two effects reduce the number of nucleation sights for thrombin generation. [33] Hydrophilic polymer surfaces Liquid repellant surfaces have been shown to play a vital role for eliminating thrombosis on medical devices, minimizing blood contamination on common surfaces as well as preventing non-specific adhesion. Herein, an all solution-based, easily scalable method for producing liquid repellant flexible films, fabricated through nanoparticle deposition and heat-induced thin film wrinkling that suppress blood adhesion, and clot formation is reported. Furthermore, superhydrophobic and hydrophilic surfaces are combined onto the same substrate using a facile streamlined process. The patterned superhydrophobic/hydrophilic surfaces show select...

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Electrodeposition is widely used to fabricate tunable nanostructured materials in applications ranging from biosensing to energy conversion. A model based on 3D island growth is widely accepted in the explanation of the initial stages of nucleation and growth in electrodeposition. However, there are regions in the electrodeposition parameter space where this model becomes inapplicable. We use liquid cell transmission electron microscopy along with post situ scanning electron microscopy to investigate electrodeposition in this parameter space, focusing on the effect of the supporting electrolyte, and to shed light on the nucleation and growth of palladium. Using a collection of electron microscopy images and current time transients recorded during electrodeposition, we discover that electrochemical aggregative growth, rather than 3D island growth, best describes the electrodeposition process. We then use this model to explain the change in the morphology of palladium electrodeposits from spherical to open clusters with nonspherical morphology when HCl is added to the electrolyte solution. The enhanced understanding of the early stages of palladium nucleation and growth and the role of electrolyte in this process provides a systematic route toward the electrochemical fabrication of nanostructured materials.