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@ccrespo.bsky.social
Please to see that the research work by group members, Reshma Mathew, PhD, Tazrin Islam Tonny, Rubej Khan, and Sourav Seth, PhD, were selected among the top 10 breakthroughs of the year at CWRU! I am very proud of them!

case.edu/news/year-di...
A year of discovery: 10 research breakthroughs at CWRU | CWRU Newsroom | Case Western Reserve University
From advancing precision medicine and examining how nail fungus affects various sports to investigating multilingual hearing behavior in noisy environ...
case.edu
December 24, 2025 at 5:10 PM
Pleased to see online our most recent publication, which is part of a Special Issue in memory of Dr. Kendric Smith.

doi.org/10.1111/php....
Alloxazine derivatives as multifunctional agents for photodynamic therapy, cancer cell imaging, and cell proliferation inhibition
Alloxazine photosensitizers, molecularly engineered through sugar conjugation and methoxy substitution to enhance solubility, photodynamic potency, and fluorescence, enable image-guided photodynamic ...
doi.org
September 6, 2025 at 1:44 PM
What is the role of pyrimidine functionalization on the chemical origins of the RNA and DNA building blocks of life?
pubs.aip.org/aip/jcp/arti...
Impact of diamino and imidazole functionalization on the photophysical properties and electronic and structural dynamics of the pyrimidine nucleobase
The photostability of DNA and RNA bases to ultraviolet radiation is essential to life, as evidenced by their ability to dissipate excess electronic energy via u
pubs.aip.org
August 8, 2025 at 5:14 PM
I am pleased to share the online publication of our latest article. I want to specially thank and acknowledge Dr. Sourav Seth for enabling organic synthesis in our group. Cheers!

pubs.acs.org/doi/full/10....
Harnessing the Excited States of 5-(5-Phenylthiophen-2-yl)-6-Azauridine as a Three-Pronged Agent for Skin Cancer Therapy: Photodynamic Action, Cell Imaging, and Cancer Cell Inhibition
Nucleoside analogs simultaneously exhibiting high fluorescence quantum yields and efficient triplet state population are rare. Such multifunctional nucleosides represent a crucial advancement for cell imaging-assisted photodynamic therapy relying on heavy-atom-free photosensitizers and hold additional promises as inhibitors of cancer cell proliferation. This study investigates the photophysical, electronic structure, excited state dynamics, and skin cancer cell photodynamic and inhibitory properties of 5-(5-phenylthiophen-2-yl)-6-azauridine (PTAU). PTAU absorbs up to 425 nm and demonstrates dual photophysical characteristics, with fluorescence and singlet oxygen quantum yields of 43 ± 1% and 52 ± 2% in acetonitrile and 12 ± 1% and 33 ± 2% in aqueous buffer, respectively. Time-resolved absorption and fluorescence spectroscopy, complemented by quantum chemical calculations, reveal the existence of two rotameric species of PTAU in solution. Both rotamers exhibit nanosecond-scale fluorescence and intersystem crossing lifetimes, as well as microsecond-scale triplet decay lifetimes. When applied to B16F10 murine melanoma cells, PTAU localizes mostly in the cytoplasm, primarily in mitochondria, and demonstrates moderate photodynamic activity, achieving IC50 values of 125 ± 5 μM and 80 ± 3 μM at photoactivation doses of 7.5 J cm–2 and 25 J cm–2, respectively, while exhibiting no cytotoxicity in the dark. Notably, PTAU also inhibits the cell proliferation of B16F10 murine melanoma and A431 human epidermoid carcinoma by more than 95% at a concentration of 250 μM in the dark. Therefore, this proof-of-concept study reveals PTAU as the first example of a nucleoside analog with potential multifunctional applications, including photodynamic action, bioimaging, and the inhibition of skin cancer cell proliferation. These findings pave the way for further developing next-generation modified 6-azauridine analogs absorbing visible to near-infrared light for their use as cell imaging-assisted PDT agents and cancer cell inhibitors, targeting potential deep-tissue cancer treatment.
pubs.acs.org
July 24, 2025 at 4:41 PM
Pleased to share our recent publication about the safety implications in the use of an artificial nucleotide for DNA expansion and therapeutic applications.

pubs.acs.org/doi/full/10....
dTAT1: An Unnatural Nucleoside Exhibiting Low Photocytotoxicity for Genetic Code Expansion
Synthetic biology aims to expand the genetic code by increasing cellular information storage and retrieval. A recent advance is the dTAT1-dNaM unnatural base pair, which is more photo- and thermostable than dTPT3-dNaM while maintaining high efficiency and fidelity in vitro and in vivo. However, the photophysics and cytotoxicity behavior of dTAT1 under UV light have not been investigated. We demonstrate that dTAT1 populates the triplet state upon 390 nm excitation but exhibits minimal cytotoxicity in cells. Analysis of reactive oxygen species indicates that dTAT1 produces a low singlet oxygen quantum yield of 17% while it generates superoxide, a less harmful reactive oxygen species. Its triplet lifetime is 2.7 times shorter than that of dTPT3, contributing to its lower photocytotoxicity. These findings highlight the potential of dTAT1 for safe genetic code expansion and therapeutic applications, providing valuable insights for designing next-generation unnatural nucleosides with minimal impact on cellular health.
pubs.acs.org
May 22, 2025 at 2:05 PM
May 20, 2025 at 4:27 PM
Here is a sneak peek of our most recent publication about the photocytotoxicity of expanding the genetic code using the dATT1 unnatural nucleoside.
April 25, 2025 at 3:40 PM
Here is a teaser of our most recent review article…
February 6, 2025 at 1:39 AM
Very proud of Eric Lee and his graduate student mentor Chris Acquah for their outstanding presentation and participation in Intersections: CWRU Undergraduate Poster Session featurung CWRU undergraduates presenting their faculty mentored research and creative projects.
December 8, 2024 at 4:27 PM
Very proud of Nitza Falcón and Tazrin Islam Tonny who in November successfully passed their oral examination to officially become Ph.D. candidates in our chemistry graduate program at CWRU. My very best wishes for both of them!
December 8, 2024 at 4:18 PM
Consider doing your chemistry graduate education at CWRU! Free application waivers are available! And check out our new facilities: case.edu/iseb/
November 26, 2024 at 8:59 PM