2022 40th Puerto Rico Interdisciplinary Scientific Meeting (PRISM) & 55th ACS Junior Technical Meeting on April 9, 2022. PRISM & JTM are the Island’s largest annual scientific forum for undergraduate and graduate STEM students to present their research projects to peers and faculty members.

The PRISM/JTM provides vertical integration of the educational pipeline by bringing together secondary school students and teachers, undergraduate and graduate students from all STEM disciplines from all major institutions of higher education in Puerto Rico. Participants are encouraged to cross-disciplinary lines by attending presentations and posters from other disciplines.    

Electronic Registration Deadline: March 18th, 2022
(this registration is required only for students presenting at the event)

Important Links:

Invited Plenary Speakers:

Carlos E. Crespo-Hernández
Department of Chemistry,
Case Western Reserve University

Development of All-Organic Photosensitizers for the Treatment of Cancer Cells Independent of the Oxygenation Status

Photodynamic therapy (PDT) is a clinically approved, noninvasive therapy for cancer treatment that relies on the administration of a photosensitizer (PS) and light to the affected area. The aim of PDT is to selectively neutralize tumor cells with minimal effects on healthy surrounding tissue. PDT is more attractive than conventional therapies such as radiotherapy and chemotherapy because it is minimally invasive, has exceptional spatiotemporal selectivity, diminished side effects, and is overall simplistic amongst other important considerations. Notwithstanding the significant benefits over traditional therapies, PDT has yet to reach its full potential primarily because optimal PSs, applicable to a wide range of cancers and biological tissues, are difficult to develop. There is a clinical need for diverse alternatives offering improved target cell selectivity and the efficiency of more than one sensitization mechanism. An approach developed in our group that is swiftly gaining increased attention is to replace the oxygen atom with a sulfur atom in carbonyl groups of existing organic molecules to red shift their absorption spectra and increase their triplet yields and the generation of singlet oxygen and other reactive oxygen species. Many of these all-organic PSs are inexpensive to make and offer good biocompatibility, biodegradability, minimal dark cytotoxicity, and structural stability. In this presentation, I will show that fundamental physicochemical investigations can be used to envision and develop all-organic PSs exhibiting tunable absorption spectra from the ultraviolet-A (UVA) to the near infrared (IR) regions of the electromagnetic spectrum and nearly 100% greater photoreactivity than the carbonyl counterparts. When applied in vitro with a low dose of light, these PSs substantially decrease the proliferation of cancer cells. In the first example of all-organic PSs developed in our group, the unique structural, biochemical, and photochemical properties of sulfur-substituted DNA and RNA bases will be discussed. When activated with UVA radiation, these thiobases offer an attractive strategy for developing highly effective and highly targeted phototherapeutic compounds, working both in the absence and in the presence of molecular oxygen. In a second example, I will present our most recent results for all-organic PSs absorbing near visible and near IR radiation, which exhibit excellent PDT efficacy in vitro against monolayer melanoma, cervical, and HeLa cancer cells independent of the oxygenation status (i.e., under both normoxic and hypoxic conditions). 

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