Researchers at UC San Diego have developed a dipeptide composed of two arginine (Arg-Arg) that is capable of inducing the assembly of citrate-capped gold nanoparticles (AuNPs-citrate). Surprisingly, the resulting Arg-Arg-AuNPs are stable over time as the peptide protects the particles from degradation. The assemblies can even be dried without any loss of particles. The assembly of AuNPs-citrate changes their optical properties and the color of the suspension turns from red to blue. Importantly, the assemblies can be dissociated with thiolated polyethylene glycol (HS-PEGs) molecules which leads to the recovery of the initial optical properties of the AuNPs, i.e. the red color of the suspension. Surprisingly, we have observed that such dissociation of AuNPs assemblies is not sensitive to the composition of the medium. It can thus be performed in biological fluids such as pure plasma, saliva, urine, bile, cell lysates or even sea water.

Plant viral nanoparticles (plant VNPs) are promising biogenetic nanosystems for the delivery of therapeutic, immunotherapeutic, and diagnostic agents. The production of plant VNPs is simple and highly scalable through molecular farming in plants. Some of the important advances in VNP nanotechnology include genetic modification, disassembly/reassembly, and bioconjugation. Although effective, these methods often involve complex and time-consuming multi-step protocols.

Polybrominated diphenyl ethers (PBDEs) are a common brominated flame retardant, which are commonly found in consumer products. Because they are not chemically bound to polymers, PBDEs are blended in during formation and have the ability to migrate from products into the environment.  Studies suggest that PBDEs pose potential health risks such as hormone disruptors, adverse neurobehavioral toxins and reproductive or developmental effects.  For this reason it is important to have the capability to sense the presence of PBDEs even in low concentrations.

Piezoelectric sensors have long existed to monitor applied pressures between two objects. In large applications with malleable substrates or where low cost is key, individual piezoelectric sensors are not practical. A variety of applications exist where monitoring the pressure being applied to a soft surface would providing meaningful insights into the system or subject under observation. For instance, in a long-term care setting where patients need to be monitored for pressure ulcers, a bedding material that could sense the pressure points between a person’s body and the mattress could alert care givers that an adjustment in body position is warranted. Likewise, in a sports training application, a pressure sensitive boxing ring canvas could track a boxer’s footwork, or punching power and hand speed if applied to the inside of a punching bag.   Pressure sensitive soft toys could also benefit from feedback that might differ when a child scratches behind their stuffed animal’s ears vs. rubbing its belly.  To achieve discrete sensing in these applications, a low cost bulk sensing system is needed.

Conventional pigments are used to color materials and are subject to fading in ultraviolet light as well having the potential toxicity associated with conjugated organic pigments. Recently, there has been an interest in replacing these conventional pigments with so called structural colors which allow for the creation of a spectrum of nonfading colors without pigments. Moreover, these new structures create color and cause light to scatter. The creation of these new structures have been challenging, but researchers have developed a technique that can transcend these obstacles.

Broadband absorbers are essential components of many light detection, energy harvesting and camouflage schemes. Materials that “perfectly” absorb light already exist, but they are bulky and can break when bent. They also cannot be controlled to absorb only a selected range of wavelengths, which is a disadvantage for certain applications. In addition, transferring planar materials to flexible, thin or low-cost substrates poses a significant challenge.

Brief description not available

Mechanically flexible piezoelectric materials are highly sought after when building advanced sensors, actuators, and energy scavenger devices. The most common piezoelectric materials used in applications are focused on electroceramic thin films made from lead zirconate titanate or barium titanate. Although these materials can have large piezoelectric moduli, as thin films they are extremely brittle and difficult to shape into highly mechanically compliant structures. Improving mechanical flexibility of piezoelectrics, and creating higher order structures, is critical for driving new applications such as biological energy harvesting, compact acoustic transducers, and in vivo biodiagnostics.  There is a need to develop alternative materials that offer high piezoelectric coefficients while maintaining elasticity and isotropic mechanical integrity—that are also cheap to produce.

Light emitting diodes (LEDs) directly convert electronic modulations into light signals and play an essential role in optical wireless communications links. Modulation speed and quantum efficiency of LEDs have been major challenges in achieving better optical wireless communications systems. Plasmonic structures represent a promising approach to improve both the brightness and speed of LEDs because of the delicate dynamic interactions between the light emission materials and surface plasmons. In current plasmonic-based LEDs, the plasmonic enhancement frequencies are typically misaligned with the light emission frequencies of the LEDs, significantly limiting their practical applications. Of relevance to this problem are artificially engineered materials, or metamaterials, with unique properties not attainable with naturally occurring substances. 

Nucleic acids have exceptional potential in the preparation of complex nanostructured materials for use as therapeutic agents and as powerful investigative tools. However, unmodified nucleic acids are inherently susceptible to enzymatic degradation in biological milieu, limiting their practical utility in detection and as therapeutics in real world applications. Specifically, new strategies are needed for the preparation of well-defined, stable and competent nucleic acid-based materials.

Brief description not available

Concentrated solar power and solar hot water systems convert sunlight to thermal energy (heat) by using solar absorbers. For efficient operation, the solar absorber has to effectively absorb the solar energy without emitting much of its own blackbody radiation. As most materials do not possess such features naturally, a spectrally selective coating (SSC) is usually needed. Ideally SSCs would possess: (a) high absorption (0.95) in the solar spectrum (0.3-1.5 microns); (b) low emissivity in the IR spectrum (1.5-2 microns) corresponding to the blackbody radiation of the surface temperature of the solar receiver; and, (c) excellent durability at elevated temperatures, preferably in air and with humidity. Further, the coating performance should not degrade significantly during the lifetime of a solar thermal system, and the coating and its adhesion to the substrate must have excellent thermal cyclability due to the intermittent nature of solar irradiation.

Lighting is a major contributor to electricity consumption, accounting for 19 percent of global use and 34 percent in the U.S. The U.S. lighting market is currently dominated by the incandescent light bulb and is only 5percent efficient whereas the fluorescent lamp is 15 to 25 percent efficient. Compact fluorescent lamps (CFLs) have a rated lifespan of 6,000 to 15,000 hours whereas incandescent bulbs have a lifespan of only 750 to 1,000 hours. On the other hand, CFLs contain small amounts of mercury, a neurotoxin, which gets released with breakage. Solid-state luminaires, which are typically based on light-emitting diodes (LEDs), have the potential to revolutionize the industry with higher efficiency, lower maintenance, and better quality/safety, possibly leading to a reduction by half of energy consumed by general illumination.

The elastic properties of a biomaterial tissue scaffold reflect its ability to handle external loading conditions and must be tailored to match the attributes of the native tissue that it aims to repair. A scaffold’s elastic modulus and Poisson’s ratio describe how it supports and transmits external stresses to the host tissue site. (The Poisson ratio is positive/negative when the material contracts/expands transversally with axial expansion; “auxetic” materials are materials that exhibit negative Poisson ratio.) While the elastic modulus is tunable in scaffolds, the Poisson’s ratio of virtually every porous tissue construct is positive. There have been no reports of solid-phase micro-cellular biomaterials synthesized with a precisely-tuned negative Poisson’s ratio. Others have formed auxetic polyurethane foams by compressing the foams and annealing them while compressed; however, the annealing process renders little practical control over the cellular microstructure comprising the foams, making it very difficult to tune the strain-dependent behavior of Poisson’s ratio. Additionally, the foams have little to no use in biological applications involving the interactions between biomaterials and living tissue (e.g., tissue engineering applications) and other biological applications.

Researchers have proposed the use of carbon nanotubes (CNTs) as electrodes in electrochemical capacitors and supercapacitors primarily due to their large surface area, abundance of reaction sites, and the possibility of large-charge storage capacity and capacitance. While possessing superior power densities due to fast charge/discharge capabilities, CNT based capacitors have lower energy densities compared to batteries, making them less competitive for most energy-storage applications. The invention provides an approach that overcomes this disadvantage.

A significant part of past work on artificial nanomotors involves catalytic nanowire motors that self-propel in the presence of a specific fuel, e.g. hydrogen peroxide. However, many applications of nanomachines require elimination of the fuel requirement.

Nanoparticles capable of reversible changes in morphology in response to specific stimuli are expected to have broad utility in designing targeted drug-delivery, detection strategies, self-healing materials, and templates for hierarchical directed assembly. While there are several elegant examples of stimuli-responsive soft nanoparticles, programmable materials with the requisite shape-change properties remain elusive.

High-throughput and low-cost techniques for fabrication at sub-50nm scale on wide area substrates are currently a very active and competitive field of cross-disciplinary R&D. Of the recent crop of nanofabrication technologies, dip-pen nanolithography (DPN) is notable for its success in serving the nanofabrication needs of biotechnology, advanced materials, and nano-scale devices. In DPN, molecules in an “ink” are transferred from a coated atomic force microscopy tip to a substrate, forming a pattern as the tip is scanned. DPN however has the disadvantages of slow processing and patterning of small areas and limited parallelization capabilities.

Brief description not available

Cleantech is an emerging sector of innovation and deals with products and processes that harness renewable energy sources, minimizes pollution and waste, and reduces the depletion of natural resources, including water supply. There are two different technical approaches for self-cleaning coatings: hydrophobic versus hydrophilic. Both types of coatings clean themselves through the action of water. In the case of the hydrophobic surface, rolling droplets take away the dirt and dust. In the case of the hydrophilic surface, sheeting water carries away dirt. For hydrophobic surfaces, an indicator of their effectiveness is the contact angle of the water on the surface, which measures the amount of surface tension induced by the coating on the water.

Brief description not available

Photovoltaics have thus far been largely based on semiconductors, e.g., Si, CdTe, and cadmium indium selenide. Solar cells using these materials have increasingly been available commercially but still need improvement relative to stability, cost, and environmental concerns. A leading alternative solar-cell technology relies on photoelectrochemistry and the absorption and excited-state properties of dye molecules bound to a TiO2 substrate. Research on such dye-sensitized solar cells (DSSCs) has targeted and achieved higher efficiency. The prevailing approach in fabricating DSSCs has been based on mesoporous random networks of TiO2 nanocrystals. This approach however suffers from increases in resistance and recombination losses.