Shelly Casciato

Current Research

Chemical sensors for the detection of metals have been a growing interest in recent years.  In our research, we are utilizing a metal ion sensor which takes advantage of FRET.  In essence, FRET (Fluorescence Resonance Energy Transfer) involves two fluorophores:  one donor fluorophore and one acceptor fluorophore.  The donor fluorophore is excited by electromagnetic radiation, and then emits fluorescence at its characteristic emission wavelength.  Though some of this fluorescence will be picked up by the detector, if there is another fluorophore (an acceptor) in close proximity to the donor fluorophore, then some of this emitted radiation will be used to excite the acceptor fluorophore.  In order for this to occur, however, the emission spectrum of the donor and the excitation spectrum of the acceptor must overlap.  Once this emission energy is “transferred” from the donor to the acceptor and the acceptor fluorophore is excited, it will go through fluorescence, emitting its own characteristic emission wavelength. 

Ion exchangers are commonly used for the removal of metal from wastewaters.  The ideal exchange media should exhibit selectivity, strong binding of the metals, fast binding kinetics, large capacity, on demand metal release, and low cost.  Several chelators have been utilized for metal binding such as immobilized amino acids, short peptides, and proteins.  Natural proteins have a tertiary structure that is responsible for the formation of polydenate chelation which provides good metal extraction through strong binding.  Also, the polymeric character of synthetic peptides can allow for polydentate chlelation which can provide strong binding of the metals of interest.  However, there is a major difference in synthetic peptides and natural proteins’ structure.  Synthetic peptides have durability due to the absence of a preformed tertiary structure.  Therefore, the synthetic peptides are flexible enough to allow the peptide backbone to essentially “wrap” around the metal as it binds.  In our research, such property is utilized in regards to our peptide chain for the detection of metals.   After binding metal ions to selective peptide chains between a donor and acceptor fluorophore, our peptide will “wrap” around the metal ions, causing the two fluorophores’ distance to decrease and, therefore, increase the likelihood of FRET occurrence as shown in the Figure below.  Such mechanism can prove useful as a chemical sensor for the detection of metal ions.  Also, it is our intent of immobilizing these peptide chains in some fashion to allow for this mechanism to be incorporated into a mobile sensing device.

Undergraduate Research

As an undergraduate, I had the opportunity to be involved with two very different research projects.  In the summer of 2006, I worked as an intern at the University of Texas in Austin for their Biomedical Engineering Department.  I worked for Dr. Lisa Brannon-Peppas and her graduate student, Dr. Tania Betancourt, researching the incorporation of poly(ethylene glycol) (PEG) onto the surface of PLA/PLGA nanoparticles for the use as active targeting agents.  While at UTPA, I worked in Dr. Thomas Whelan’s lab, examining trace metal concentration trends in drinking water across the Rio Grande Valley.  

Peer-Reviewed Publications

• Betancourt, Tania; Byrne, James D.; Sunaryo, Nicole; Crowder, Spencer W.; Kadapakkam, Meena; Patel, Shefali; Casciato, Shelly; Brannon-Peppas, Lisa.  PEGylation strategies for active targeting of PLA/PLGA nanoparticles.  Journal of Biomedical Materials Research Part A.  (Accepted for Publication)