Francesca Starvaggi

All Publications

• Accurate Determination of Reactivity Ratios for Copolymerization Reactions with Reversible Propagation Mechanisms MACROMOLECULES Lundberg, D. J., Kilgallon, L. J., Cooper, J. C., Starvaggi, F., Xia, Y., Johnson, J. A. 2024; 57 (14): 6727-6740

  View details for DOI 10.1021/acs.macromol.4c00835

  View details for Web of Science ID 001275465100001

• Ring Opening Metathesis Polymerization of Cyclooctadiene and Cyclooctene with Dihydrofuran: Influence of Ru Fischer Carbene. ACS macro letters Starvaggi, F. A., Suslick, B. A., Xia, Y. 2024: 296-301

  Abstract

  Vinyl ethers are commonly used to deactivate Grubbs catalysts and terminate ring opening metathesis polymerization (ROMP) by forming Fischer carbene species with attenuated metathesis reactivity. However, we recently demonstrated that a cyclic enol ether, 2,3-dihydrofuran (DHF), can in fact be homopolymerized or copolymerized with norbornene derivatives. 1,5-Cyclooctadiene (COD) and cyclooctene (COE) consist of an important class of ROMP monomers, and we describe here a study of their copolymerization with DHF. Addition of DHF greatly suppressed the ROMP activity of COD and COE and resulted in significant alkene isomerization of COD. Chloranil was found to be an effective additive to prevent undesired isomerization and promote copolymerization. As a result, high molecular weight COD/COE and DHF copolymers were synthesized. Hydrolysis of the enol ether main chain linkages yields polyalkenamers with alcohol and aldehyde end groups. This study encourages further exploration of the in situ formed Ru Fischer carbene species in ROMP to access degradable polymers.

  View details for DOI 10.1021/acsmacrolett.3c00770

  View details for PubMedID 38359364

• Tunable, bacterio-instructive scaffolds made from functional graphenic materials. Biomaterials science Eckhart, K. E., Arnold, A. M., Starvaggi, F. A., Sydlik, S. A. 2021

  Abstract

  The balance of bacterial populations in the human body is critical for human health. Researchers have aimed to control bacterial populations using antibiotic substrates. However, antibiotic materials that non-selectively kill bacteria can compromise health by eliminating beneficial bacteria, which leaves the body vulnerable to colonization by harmful pathogens. Due to their chemical tunablity and unique surface properties, graphene oxide (GO)-based materials - termed "functional graphenic materials" (FGMs) - have been previously designed to be antibacterial but have the capacity to actively adhere and instruct probiotics to maintain human health. Numerous studies have demonstrated that negatively and positively charged surfaces influence bacterial adhesion through electrostatic interactions with the negatively charged bacterial surface. We found that tuning the surface charge of FGMs provides an avenue to control bacterial attachment without compromising vitality. Using E. coli as a model organism for Gram-negative bacteria, we demonstrate that negatively charged Claisen graphene (CG), a reduced and carboxylated FGM, is bacterio-repellent through electrostatic repulsion with the bacterial surface. Though positively charged poly-l-lysine (PLL) is antibacterial when free in solution by inserting into the bacterial cell wall, here, we found that covalent conjugation of PLL to CG (giving PLLn-G) masks the antimicrobial activity of PLL by restricting polypeptide mobility. This allows the immobilized positive charge of the PLLn-Gs to be leveraged for E. coli adhesion through electrostatic attraction. We identified the magnitude of positive charge of the PLLn-G conjugates, which is modulated by the length of the PLL peptide, as an important parameter to tune the balance between the opposing forces of bacterial adhesion and proliferation. We also tested adhesion of Gram-positive B. subtilis to these FGMs and found that the effect of FGM charge is less pronounced. B. subtilis adheres nondiscriminatory to all FGMs, regardless of charge, but adhesion is scarce and localized. Overall, this work demonstrates that FGMs can be tuned to selectively control bacterial response, paving the way for future development of FGM-based biomaterials as bacterio-instructive scaffolds through careful design of FGM surface chemistry.

  View details for DOI 10.1039/d0bm01471k

  View details for PubMedID 33404025