Our group currently working in three broad areas (a) Energy storage (b) Contaminant detection in sea and fresh water (c) Influence of anthropogenic stressors such as microplastics on marine and freshwater bacteria.
We are developing all-solid lithium ion batteries for active implantable medical devices, and for unmanned underwater vehicles, that are much safer than current batteries that contain organic liquid electrolytes. Our strategy is to use a combination of polymer-based electrolytes and active materials to deliver high cycle stability and the power and energy required for these diverse applications. We have developed novel processing strategies for making batteries with silicon-based anodes, and examined the composition and morphology of the growing solid electrolyte interphase layer from graphite and silicon anodes.
Funding: DOE, ONR (through the National Institute for Underwater Vehicle Technology), RI Innovation Voucher, EaglePicher.
Analyte detection in sea and fresh water
We are developing hybrid carbon-gold nanoparticles that can be used for detecting a broad spectrum of analytes using Surface Enhanced Raman Scattering. Our immediate focus is the detection of nitrate and phosphate ions in ‘natural’ water. This is important because excess nitrates and phosphates in water (typically from fertilizer runoff after storms) cause algae blooms that result in local hypoxia with deleterious consequences on marine and freshwater organisms.
In a parallel effort, we are doping our SERS particles in algae leaves that act as bioconcentrators for nitrate ions, to detect this analyte at low concentrations. The algae leaves naturally filter out debris that can confound detection, and they do not biofoul easily, making them potentially robust sensors.
Funding: National Science Foundation.
Influence of microplastics on marine and freshwater bacteria
About 150 million tons of plastic are in the world’s oceans currently, and 8 million additional tons are dumped into the ocean each year. By 2050, the weight of plastics in the ocean will exceed the weight of all marine organisms. These are highly concerning statistics, since plastics, (mostly polyethylene) in the ocean do not degrade easily, and can impact marine life for over a hundred years. Through ocean action, light and wind exposure these plastics eventually break up into millimeter- and lower-sized objects, or microplastics. Microbeads were also prevalent in personal care products such as exfoliating shower gel, toothpaste, and makeup, which eventually ended up in the ocean. A range of sea creatures, such as oysters and fish, are known to consume these microplastics. with inevitable negative consequences up the food chain.
Important natural processes that follow a polluting stressor are bacterial colonization and degradation, and they can be used to assess resilience. Cyanobacteria (CB) is a gram-negative bacterium, prevalent in abundance in ocean waters. CB senses, then attaches and responds biologically to microplastics, either by mutating for its own survival or by developing enzymes that degrade these plastics. We have exposed CB to microplastics, and then used time-resolved cryogenic scanning electron microscopy and fluorescence microscopy to monitor CB attachment, and the development of biofilms. We have sequenced CB DNA to understand mutations caused by exposure to microplastics.
Funding: RI Science and Technology Advisory Council.