Marvin Pollum

PPG Industries | PPG

The thiopurine prodrugs 6‐mercaptopurine and azathioprine are among the world’s essential medications for acute lymphoblastic leukemia, immunosuppression, and several autoimmune conditions. Thiopurine prodrugs are efficient UVA absorbers and singlet oxygen generators and the long‐term treatment with these prodrugs correlates with a high incidence o...

The thiopurine prodrugs 6-mercaptopurine and azathioprine are among the world’s essential medications for acute lymphoblastic leukemia, immunosuppression, and several autoimmune conditions. Thiopurine prodrugs are efficient UVA absorbers and singlet oxygen generators and the long-term treatment with these prodrugs correlates with a high incidence o...

The thiopurine prodrugs 6-mercaptopurine and azathioprine are among the world’s essential medications for acute lymphoblastic leukemia, immunosuppression, and several autoimmune conditions. Thiopurine prodrugs are efficient UVA absorbers and singlet oxygen generators and the long-term treatment with these prodrugs correlates with a high incidence o...

Dissimilar metal joining is of increasing interest in many structural applications due to its potential to enable light weighting. Light-weight substrates such as aluminum alloys, magnesium alloys and carbon-fiber reinforced polymer (CFRP) are increasingly used in place of conventional steels due to their high strength-to-weight ratios. Two of the...

Sulfur‐substituted nucleobases (a.k.a., thiobases) are among the world's leading prescriptions for chemotherapy and immunosuppression. Long‐term treatment with azathioprine, 6‐mercaptopurine, and 6‐thioguanine has been correlated with the photoinduced formation of carcinomas. Establishing an in‐depth understanding of the photochemical properties of...

Sulfur-substituted nucleobases (i.e. thiobases) are a prospective class of compounds for clinical and cosmetic topical phototherapies. Recent investigations of several thiobases have revealed the ultrafast and efficient population of reactive triplet states upon UVA irradiation and the subsequent generation of singlet oxygen in high yield. In this...

Single-atom substitution within a natural nucleobase—such as replacing oxygen by sulfur in uracil—can result in drastic changes in the relaxation dynamics after UV excitation. While the photodynamics of natural nucleobases like uracil are dominated by pathways along singlet excited states, the photodynamics of thiobases like 2-thiouracil populate t...

Enteroviruses use a type I IRES structure to facilitate protein synthesis and promote genome replication. Type I IRES elements require auxiliary host proteins to organize RNA structure for 40S ribosomal subunit assembly. Heterogeneous nuclear ribonucleoprotein A1 stimulates Enterovirus 71 (EV71) translation in part through specific interactions wit...

Photosensitization of DNA by thionucleosides is a promising photo-chemotherapeutic treatment option for a variety of malignancies. DNA metabolization of thiated prodrugs can lead to cell death upon exposure to a low dose of UVA light. The exact mechanisms of thionucleoside phototoxicity are still not fully understood. In this work, we have combined...

In 2014, two unnatural nucleosides, d5SICS and dNaM, were shown to selectively base pair and replicate with high fidelity in a modified strain of E. coli, thus effectively expanding its genetic alphabet from four to six letters. More recently, a significant reduction in cell proliferation was reported in cells cultured with d5SICS, and putatively w...

Elucidating the photophysical mechanisms in sulfur-substituted nucleobases (thiobases) is essential for designing prospective drugs for photo-and chemotherapeutic applications. Although it has long been established that the phototherapeutic activity of thiobases is intimately linked to efficient intersystem crossing into reactive triplet states, th...

Supplementary Figures 1-8, Supplementary Tables 1-7, Supplementary Notes 1-3 and Supplementary References

The base-pair d5SICS•dNaM was recently reported to incorporate and replicate in the DNA of a modified strain of E. coli, thus making the world’s first stable semi-synthetic organism. This newly expanded genetic alphabet may allow organisms to store considerably more information in order to translate proteins with unprecedented enzymatic activities....

Correction for 'Photochemical etiology of promising ancestors of the RNA nucleobases' by M. M. Brister et al., Phys. Chem. Chem. Phys., 2016, DOI: .

The photodynamic properties of molecules determine their ability to survive in harsh radiation environments. As such, the photostability of heterocyclic aromatic compounds to electromagnetic radiation is expected to have been one of the selection pressures influencing the prebiotic chemistry on early Earth. In the present study, the gas-phase photo...

RNA is a product of chemical and biological evolution and the identification of its heterocyclic ancestors is essential for understanding the molecular origins of life. Among a diverse array of selection pressures thought to have shaped the composition of the nucleobases on prebiotic Earth, protection against intense ultraviolet radiation must have...

Thiopurine prodrugs are currently among the leading treatment options for leukemia, immunosuppression, and arthritis. Patients undergoing long-term thiopurine treatment are at a higher risk of developing sunlight-induced skin cancers than the general population. This side effect originates from the cellular metabolization of thiopurine prodrugs to...

The ability of 4-thiouracil to strongly absorb UVA radiation and to populate a reactive triplet state in high yield has enabled its use as a versatile photocrosslinker for nearly 50 years. In this contribution, we present a detailed spectroscopic and photochemical investigation of the 2-thiouracil, 4-thiouracil, and 2,4-dithiouracil series in an ef...

The excited-state dynamics of the purine free base and 9 methylpurine are investigated using experimental and theoretical methods. Femtosecond broadband transient absorption experiments reveal that excitation of these purine derivatives in aqueous solution at 266 nm results primarily in ultrafast conversion of the S2(ππ*) state to the vibrationally...

Substitution of both oxygen atoms in the exocyclic carbonyl groups of the thymine chromophore by sulfur atoms results in a remarkable redshift of its absorption spectrum from an absorption maximum at 267 nm in thymidine to 363 nm in 2,4-dithiothymine (ΔE = 9905 cm–1). A single sulfur substitution of a carbonyl group in the thymine chromophore at po...

The steady-state and time-resolved photochemistry of the natural nucleic acid bases and their sulfur- and nitrogen-substituted analogues in solution is reviewed. Emphasis is given to the experimental studies performed over the last 3–5 years that showcase topical areas of scientific inquiry and those that require further scrutiny. Significant progr...

Femtosecond broadband transient absorption experiments are reported for 2-thiothymine and 2-thiouracil in aqueous buffer solution and in acetonitrile. It is shown that the S1(nπ*) state acts as a doorway state in the ultrafast and efficient population of the T1(ππ*) state upon 316 nm excitation. A sequential kinetic model is presented to explain th...

Dye-sensitized solar cells (DSSCs) are a promising alternative to the current silicon solar cell technologies. DSSCs have a lower manufacturing cost, can be made to be flexible, semi-transparent, and in any variety of colors for aesthetic applications. Despite these advantageous properties, the stability and power conversion efficiency of DSSCs are...

According to Förester's equations, the efficiency (EFRET) of resonance energy transfer between fluorophores is governed by three factors: separation distance, relative orientation of transition dipole moments, and the spectral overlap integral. We've designed an ideal architecture for controlling each of these parameters by covalently linking FRET...