C60 is the most common and stable form of a unique family of all-carbon spheroids known as Buckminsterfullerenes, or fullerenes for short. While past environmental studies mostly focused only on pristine C60, it is becoming more common to chemically modify fullerenes, which makes it difficult to assess their potential environmental impacts as fullerene derivatives. Chemically modified, or functionalized, C60 provides tremendous opportunities for applications in diverse fields including biocidal materials for water and surface disinfection, due to C60's unique property of mediating the transfer of light energy to ambient oxygen, producing reactive singlet oxygen (1O2). The production of 1O2, however, can also have negative consequences to biological systems upon unintended release into the environment. Since C60 is very insoluble in water, it forms stable, nano-sized aggregates that lose the ability to produce 1O2. Functionalizing C60, however, has been found to allow C60 to achieve more dispersion in water and generate 1O2. These properties are strongly affected by the type and the number of chemical functional groups attached to the fullerene cage, yet no systematic studies have been conducted on the relationship between photochemical activity and functionalization of fullerene aggregates to date.
Intellectual Merit: This project will examine a series of fullerene derivatives to better understand the relationship between functionalization of C60 and its key properties of interest for environmental implications and applications. Such properties include absorption of light in visible and UVA range, capability to transfer energy to oxygen and produce 1O2, water solubility or ability to disperse as aggregates, and surface interactions with microorganisms. Experimental plans were developed to examine (1) physical and chemical properties; (2) photochemical properties; and (3) kinetics and mechanisms of antibacterial and antiviral properties, using a suite of analytical techniques and microbiological tools. The proposed study is one of the first studies to establish a foundation for predicting the properties of fullerene derivatives in water based on their functionalities and will significantly contribute to advancing knowledge on functionalizing fullerene in the context of environmental implications. This study will also provide the necessary information for the utilization of functionalized fullerenes in environmental remediation. The first, realistic step toward these goals would be examining the key relationships on a selected range of fullerene derivatives that are of utmost significance in terms of availability and commercialization potential.
Broader impacts: Educating graduate students is an integral part of the proposed project and the PI intends to recruit students in underrepresented groups. This project will train students in an emerging area where qualified professionals are in short supply. These students will gain interdisciplinary experience with applications of nanochemistry, photochemistry and environmental engineering. The project will also leverage an existing high school student summer internship program.
