Thesis (M.S.)--Rochester Institute of Technology, 1994. / Typescript. Includes bibliographical references (leaf 82).

A series of polypeptides with well-defined sequences, (Asp3Phe1)n, (Asp2Phe1)n, (Asp1Phe1)n, (Asp1Phe2)n, and (Asp1Phe3)n, containing the hydrophilic amino acid, aspartic acid (Asp) and the hydrophobic amino acid, phenylalanine (Phe), were synthesized. Their behaviour in aqueous solution was investigated by performing fluorescence quenching and non-radiative energy transfer (NRET) experiments which were complemented by dynamic (DLS) and static (SLS) light scattering. The photophysical properties of the polypeptides were dependent on their Phe content. An increase in the Phe content led to an increase in the extinction coefficient, fluorescence quantum yield, and fluorescence average lifetime of the polypeptides. Circular dichroism experiments revealed that except for the (Asp1Phe3)n polypeptide, which adopts an alpha-helical conformation in aqueous solution, the other polypeptides did not adopt any known conformation in solution. The fluorescence quenching studies performed using molecular pyrene physically bound to the polypeptide via hydrophobic interactions resulted in protective quenching for the (Asp1Phe1)n, (Asp1Phe2)n, and (Asp1Phe3)n polypeptides, with some pyrenes having a lifetime of ~300 ns. Evidence for protective quenching was also observed in the polypeptides richer in Phe, when pyrene was covalently attached onto the polypeptides. However pyrene was found to be fully exposed to the quencher solution for the more hydrophilic polypeptides. The presence of NRET between a naphthalene labeled polypeptide and a pyrene labeled polypeptide for the (Asp1Phe2)n and (Asp1Phe3)n polypeptides and its absence for the (Asp3Phe1)n, (Asp2Phe1)n, and (Asp1Phe1)n polypeptides led to the conclusion that those polypeptides richer in Phe generate interpolymeric aggregates which provide protection to a hydrophobic cargo like molecular pyrene whereas the hydrophilic polypeptides exist predominantly as unimolecular micelles. These results were confirmed by DLS and SLS experiments.

A series of polypeptides with well-defined sequences, (Asp3Phe1)n, (Asp2Phe1)n, (Asp1Phe1)n, (Asp1Phe2)n, and (Asp1Phe3)n, containing the hydrophilic amino acid, aspartic acid (Asp) and the hydrophobic amino acid, phenylalanine (Phe), were synthesized. Their behaviour in aqueous solution was investigated by performing fluorescence quenching and non-radiative energy transfer (NRET) experiments which were complemented by dynamic (DLS) and static (SLS) light scattering. The photophysical properties of the polypeptides were dependent on their Phe content. An increase in the Phe content led to an increase in the extinction coefficient, fluorescence quantum yield, and fluorescence average lifetime of the polypeptides. Circular dichroism experiments revealed that except for the (Asp1Phe3)n polypeptide, which adopts an alpha-helical conformation in aqueous solution, the other polypeptides did not adopt any known conformation in solution. The fluorescence quenching studies performed using molecular pyrene physically bound to the polypeptide via hydrophobic interactions resulted in protective quenching for the (Asp1Phe1)n, (Asp1Phe2)n, and (Asp1Phe3)n polypeptides, with some pyrenes having a lifetime of ~300 ns. Evidence for protective quenching was also observed in the polypeptides richer in Phe, when pyrene was covalently attached onto the polypeptides. However pyrene was found to be fully exposed to the quencher solution for the more hydrophilic polypeptides. The presence of NRET between a naphthalene labeled polypeptide and a pyrene labeled polypeptide for the (Asp1Phe2)n and (Asp1Phe3)n polypeptides and its absence for the (Asp3Phe1)n, (Asp2Phe1)n, and (Asp1Phe1)n polypeptides led to the conclusion that those polypeptides richer in Phe generate interpolymeric aggregates which provide protection to a hydrophobic cargo like molecular pyrene whereas the hydrophilic polypeptides exist predominantly as unimolecular micelles. These results were confirmed by DLS and SLS experiments.

Thesis (M.S.)--Ohio University, June, 1987. / Title from PDF t.p.

Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xi, 160 p.; also includes graphics (some col.). Includes bibliographical references (p. 146-160). Available online via OhioLINK's ETD Center.

In this paper, an improved method [1] for the chemical synthesis of 2SeU-RNA was reported using a streamlined strategy employs 2'-O-Thiomopholine-4-carbothioate protecting group. And single step deprotection of the resulting oligoribonucleotide product using 1,2-diamines/toluene under anhydrous conditions would retain the Selenium atom introduced on the 2-possiton of the modified Uracil. The process is doable with most standard heterobase protection and deprotection, it greatly simplifies the synthesis of 2SeU-RNAs and can be applied to other Selenium modified RNAs synthesis. It makes the synthesis of RNA become as simple and efficient as the chemical synthesis of DNA. Furthermore, the design and synthesis of self-assembling 2SeU-RNA square are reported which enable further structure studies and application of unique 2SeU-RNAs.

Preliminary work towards the development of novel biosensing interfaces for EMPAS (ElectroMagnetic Piezoelectric Acoustic Sensor) is presented in this manuscript. This method involves the use of unprecedented thiosulfonate-based linkers to construct robust and durable SAMs (Self-Assembling Monolayer) onto piezoelectric quartz crystals, which can chemoselectively immobilize thiol-containing biomolecules under aqueous conditions in a single, straightforward, reliable and coupling-free manner. Initial efforts are devoted to the construction of SAMs and the subsequent immobilization of thiol-containing biomolecules, and then characterization by CAMs (Contact Angle Measurement) and ARXPS (Angle-Resolved X-ray Photoelectron Spectroscopy). This method is then implemented into the construction of biosensing interfaces dedicated to the detection of avidin. With the incorporation of OEG (Oligo(Ethylene Glycol)) backbone and diluent in the method, 14-fold difference in signal response of EMPAS was observed between biotinylated and unfunctionalized SAMs.

Preliminary work towards the development of novel biosensing interfaces for EMPAS (ElectroMagnetic Piezoelectric Acoustic Sensor) is presented in this manuscript. This method involves the use of unprecedented thiosulfonate-based linkers to construct robust and durable SAMs (Self-Assembling Monolayer) onto piezoelectric quartz crystals, which can chemoselectively immobilize thiol-containing biomolecules under aqueous conditions in a single, straightforward, reliable and coupling-free manner. Initial efforts are devoted to the construction of SAMs and the subsequent immobilization of thiol-containing biomolecules, and then characterization by CAMs (Contact Angle Measurement) and ARXPS (Angle-Resolved X-ray Photoelectron Spectroscopy). This method is then implemented into the construction of biosensing interfaces dedicated to the detection of avidin. With the incorporation of OEG (Oligo(Ethylene Glycol)) backbone and diluent in the method, 14-fold difference in signal response of EMPAS was observed between biotinylated and unfunctionalized SAMs.

We used self-assembling tunnel junctions (SATJs) to study the electron transport through films of the molecular magnets, Mn12-Acetate. Pulse laser deposition (PLD) was used to deposit two monolayers of Mn12-Acetate on thin Pt wires (diameter 0.001 in). The electron tunneling current was measured with typical bias voltages from -1 to 1 V at liquid helium temperature, 4.2 K. I, dI/dV , and d2I/dV 2 signals were directly acquired with the aid of a current amplifier and two lock-in-amplifiers. Results show that the differential conductance is approximately 10â 6 S for bias voltages 0.04 V < or =| V |< or = V and exhibits a strong voltage dependence. In the region | V |< or = 0.04 V, we find a zero-bias feature (ZBF) in which the differential conductance is suppressed. In some samples, we observe I -V staircases which we attribute to electrons "hopping" between the electrodes and the molecules. The observed hysteresis was attributed to the slow relaxation of molecules re-orienting within the junction. Abrupt conductance jumps at a bias voltage of -0.12 V were also observed and may indicate state transitions in the Mn12-Acetate molecules. Furthermore, we observed that the zero bias feature (ZBF) can switch from an enhancement to a suppression of the differential conductance. A dip and dry (DAD) method was also used to form films of Mn12-Acetate on Al and Pt wires. Although the conductances were similar to those obtained using the PLD method, there were some subtle differences. In particular, we did not observe the I -V staircases and the state jumps were more ambiguous. The differential conductance for the Mn12-Acetate films on Al wires were typically 10- 7 S, which we attributed to the oxide layer on Al surfaces. We have also found substantial changes in the I - V characteristics when the Pt wires coated with the Mn12-Acetate films were stored in 10-2 Torr for 6 months. In particular, we observed many new features such as peaks in the conductance as a function as the bias voltage. We believe that these effects may be caused by the slow oxidation of the Mn12-Acetate molecules.

Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2002. / Includes bibliographical references (leaves 140-148). Also available in electronic version. Access restricted to campus users.