Recent advances in glylons science

A variety of sugar- based polyamides called glylons were synthesized by using different pathways. The sugar- units were derived from D- glucaric acid and D-galactaric acid. Glylons D-glucaric- based with pendant free hydroxyl groups showed a low solubility in organic solvents, due to hydroxyl preference to form strong intra- and intermolecular H- bonding. To minimize these interactions an acetalation reaction was performed. Monoacetalated D-glucaric-based po-lymers exhibited a better solubility in a broader range of solvents but the residual hydroxyl groups favored aggregation. Completely blocked bis-acetalated galactaric-based glylons are so-luble in a broad range of solvents including toluene/methanol mixtures. Deprotection reaction performed with hydrofluoric acid led to the initial problem of solubility. A combination of techniques such as FTIR, 1H, 13C, COSY NMR, MALDI-TOF, GPC, DSC and TGA were employed to characterize the synthesized glylons. The course of the poly-meri¬zation reaction was monitored with FTIR and NMR. Cyclic and linear species were identi-fied with MALDI-TOF mass spectrometry. The cyclization leads to premature termination and only low molecular weight glylons can be isolated. The ration linear to cyclic varies for glylons with both odd-carbon numbered and even-carbon numbered diamines. Glylons bearing pro¬pylene di¬amine units have a higher ratio of linear species when compared with glylons having hexame-thylene diamine units. These conformers were identified also by GPC, DSC and TGA. Furthermore, GPC technique suggests the existence of a higher molecular weight polymer frac-tion. Thermal analysis pointed out that glylons are low crystalline polymers. Organized patterns resembling tree-rings were found to form in solutions of deprotected glylons (gly-6, 6 and GalEt_unpr) in NMMO monohydrate and BMIMCl. The investigation of their morphologies was performed with optical, polarized light and confocal microscopy,small/wide angle light scattering as well. The thickness of the rings was noted to be highly influenced by the concentration, temperature, viscosity and the surface available for growth. In dimethylsulfoxide deprotected galactaric glylons were found to form gels

Silica Polypeptide-Based Colloids: Physical Properties and Novel Materials

The investigation of polypeptide composite particles, PCPs, is described. The production of mesoporous and polycolloid architectures is also addressed. PCPs were prepared by both growing form and grafting to method. They consist of a core made of silica, silica-coated magnetite or silica-coated cobalt. Some of the particles were covalently labeled with fluorescein isothiocyanate. Several polypeptides were chosen for attachment on the core: poly(γ-stearyl-L-glutamate), PSLG, poly(Nε-carbobenzyloxy-L-lysine), PCBL and poly(o-benzyl-L-tyrosine), PBTY. Attachment of a well-characterized alkyne-end terminated PSLG and PCBL to an azide- functionalized particle yielded PCPs with a desired sparse coverage. A blend of techniques such as FTIR, XPS, TEM, HTEM, XRD, GPC, MALDI-TOF, DLS, and SQUID was used to confirm their production and to investigate their properties. The near superparamagnetic PCBL-CPs showed thinning behavior when subjected to stress. PSLG-CPs dispersed in different surfactant aqueous solutions and also enabled the immobilization by adsorption of a lipase from Candida rugosa. Dispersed in a liquid crystal PSLG matrix they rendered interesting morphologies. Mesoporous silica structures, some called geodesics, were obtained by prolonged storage in a slightly basic solution of ammonium hydroxide. Treatment with 3mM NaOH of fluorescent silica and PCPS yielded interesting mesoporous structures. Silica fluorescent particles were easily up-taken in the living cells of the Arabidopsis thaliana leaf. A concentrated NaOH solution (~10%) was used to cleave the polypeptide shell and measure the molecular weight. The helix conformation of the shell and the molecular weight, were confirmed by GPC assays. PCBL-CPs underwent to an inverse helix-to-coil transition in m-cresol as a function of temperature. The transition was followed by DLS, DSC, NMR T1 and SAXS. The results obtained with the blend of these techniques suggested a complicated landscape for the transition. The conformational change is not a pure coil-to-helix transition, rather transient states were identified. Polycolloid architectures were obtained by using enzymatic (Horseradish peroxidase) and photolytic catalysis (PICUP-Photo-induced Cross-linking of Unmodified Proteins). Comparison between the two approaches emphasized the facile preparation of the polycolloid structures by PICUP. The technique was suitable for preparation of different architectures obtained by patterning the reaction vessels. PICUP also enabled the formation of permanent magnetic PCP chains

Organophilic, Superparamagnetic, and Reversibly Thermoresponsive Silica-Polypeptide Core-Shell Particles

Particles with a superparamagnetic cobalt inner core, silica outer core, and covalently bound homopolypeptide shell were investigated under thermal and magnetic stimuli. The homopolypeptide was poly(ϵ-carbobenzyloxy-l-lysine), PCBL, which is known to exhibit a thermoreversible coil → helix transition when dissolved as a pure polymer in m-cresol. Tethering to a core particle did not prevent PCBL from undergoing this conformational transition, as confirmed by dynamic light scattering and optical rotation, but the transition was broadened compared to that of the untethered polymer. The Co@SiO2-PCBL hybrid particles retained the superparamagnetic properties of the cobalt inner nougat. Indeed, some response remains even after aging for \u3e5 years. The aged PCBL shell also preserved its responsiveness to temperature, although differences in the shape of the size vs temperature transition curve were observed compared to the freshly made particles. A reversible coil → helix transition for a particle-bound polypeptide in a pure organic solvent is rare. In addition to providing a convenient tool for characterizing coil → helix transitions for surface-bound polypeptides without interference from pH or the strong ionic forces that dominate behavior in aqueous systems, the Co@SiO2-PCBL/m-cresol system may prove useful in studies of the effect of shell polymer conformation on colloid interactions. The stability of the magnetic core and polypeptide shell suggest a long shelf life for Co@SiO2-PCBL, which can, in principle, be deprotected to yield positively charged Co@SiO2-poly(l-lysine) particles for possible transfection or antimicrobial applications or chained magnetically to produce responsive poly(colloids)

Polypeptide Induced Organization of Semiconducting Polymers into Hybrid Electroactive Materials with Enhanced Photo Physical Properties

Presented at the Symposium on Soft Matter Forefronts "Contributed Talks", April 20, 2018, from 11:10 a.m.-12:00 p.m. in the Student Center Ballroom, Georgia Tech.Chairs: Volodymyr Korolovych & Blair Brettmann (Georgia Tech).Cornelia Rosu is with the Georgia Institute of Technology, School of Chemical and Biomolecular Engineering.Paul S. Russo is with Georgia Institute of Technology, School of Chemistry and Biochemistry and School of Materials Science and Engineering.Elsa Reichmanis is with the Georgia Institute of Technology, School of Chemical and Biomolecular Engineering, School of Chemistry and Biochemistry, and School of Materials Science and Engineering.Runtime: 10:26 minutesInteraction of biopolymers with organic electronic materials provides an appealing opportunity to design electroactive materials for use in many applications especially bioelectronics. Because of their biocompatibility, polypeptides do not act just as simple bio- components; rather they effectively influence the organization of π-conjugated polymers into highly crystalline structures that allow charge transport. The talk will focus on poly(γ-benzyl-L-glutamate), PBLG, a synthetic polypeptide that forms thermoreversible tree-dimensional networks. Blends with poly(3-hexylthiophene), P3HT, resulted in gel materials able to switch reversibly on and off their photo-physical properties. This behavior was observed during two cycles of heating-cooling-aging. Enhanced alignment of P3HT chains into J-aggregate structures, ideal for effective electronic performance, was attributed to interactions between the PBLG benzyl side chains and P3HT hexyl arms.Georgia Institute of Technology. College of SciencesGeorgia Institute of Technology. Institute for MaterialsGeorgia Institute of Technology. Parker H. Petit Institute for Bioengineering and BioscienceGeorgia Institute of Technology. School of Materials Science and EngineeringGeorgia Institute of Technology. School of PhysicsAmerican Physical SocietyExxon Mobil CorporationNational Science Foundation (U.S.

Diffusion of Rodlike Polymers: Pulsed Gradient Spin Echo NMR of Poly(γ-stearyl-α,l-glutamate) Solutions and the Importance of Helix Stability

Many natural and synthetic polymers and particles have a rodlike shape, leading to important and intriguing solution behavior, such as high intrinsic viscosities and liquid crystalline phases. Much of what is known about suspensions of rods has been learned by studying helical polypeptides, even though such molecules are not perfectly rigid, smooth cylinders. Previous optical tracer self-diffusion studies of poly(γ-benzyl-α,l-glutamate) (PBLG) revealed that the molecule initially resists topological constraints imposed by neighboring molecules, but diffusion strongly decreases as concentration rises beyond a certain number density. In contrast, the tracer self-diffusion coefficient of truly rigid tobacco mosaic virus begins decreasing immediately with concentration. We used pulsed gradient spin echo NMR to measure another polypeptide, poly(γ-stearyl-α,l-glutamate) (PSLG), to gain physical insight into the question of polypeptide diffusion in crowded isotropic solutions. The PSLG molecule, with long alkyl sidechains, is semiflexible like PBLG but does not exhibit the same ability to evade topological constraints. Instead, PSLG follows a simple exponential decay, D/ D = A e + B, where D is the Kirkwood-Riseman expectation for rod diffusion, ν is the number density of rods, ν* is the Onsager expectation for the number density at the onset of liquid crystal formation, A = 1 ± 0.1, B = 0.1 ± 0.01, and κ = 4.5 ± 0.5. The results emphasize the importance of helix stability when choosing rodlike polypeptides as model systems, particularly with regard to the chain ends

The Petroleum Systems from the Western Black Sea Basin, Romania

Although oil production has a long history in Romania, the offshore discoveries from the Western part of the Black Sea are still relatively newly developed and with further potential to be revealed. To find the best places for new wells, as well as making new oil field discoveries, it is very important to understand the petroleum system of the area. If the elements of the petroleum system are well understood, then the potential of the Black Sea will become bigger, as the complexity of the area will be acknowledged. Two major petroleum systems were discovered in the area, the thermogenic system, and the biogenic system. The thermogenic system is corresponding to the shallow area of the Black Sea, where current productive fields are, while the biogenic system is corresponding to the deeper area, currently being in the exploration stage. The purpose of this article is to present both petroleum systems from the Black Sea Romania, their elements, the evolution they had, and the major differences between the two

Poly(colloid)s: “Polymerization” of Poly(l‑tyrosine)-silica Composite Particles through the Photoinduced Cross-Linking of Unmodified Proteins Method

Photoinduced cross-linking of unmodified proteins, PICUP, was extended to core–shell silica-polypeptide composite particles to produce poly­(colloid)­s. Silica particles coated with poly­(l-tyrosine), PTYR-SiO₂, served as the monomer units. The PICUP reaction accomplished the formation of dityrosil linkages between the tyrosine units by illumination of photo-oxidizing ruthenium­(II) bipyridyl catalyst under physiological conditions. The PICUP method was compared with an enzymatic route intermediated by horseradish peroxidase as catalyst. The PTYR-SiO₂ particles feature high PTYR content in the shell, which facilitated the formation of heavily cross-linked but unstructured aggregates. After magnetic alignment of superparamagnetic PTYR-SiO₂-cobalt composite particles, only the PICUP approach enabled the preparation of isolated chain-like poly­(colloid)­s. The cross-linking products were confirmed by FTIR. The native secondary structure of poly­(l-tyrosine) is preserved in these poly­(colloid)­s. Because the PICUP reaction does not require the modification of the polypeptide structure, the cross-linked PTYR will retain its characteristic functions as a poly­(amino acid). The PICUP method opens the door to a variety of PTYR-based poly­(colloid) architectures

Polypeptide-Coated Silica Particles Dispersed in Lyotropic Liquid Crystals of the Same Polypeptide

When a particle is introduced into a liquid crystal (LC), it distorts the LC director field, leading to new arrangements of the particles. This phenomenon is ordinarily studied using \u3e100 nm particles and ∼2 nm mesogens. Usually the particle surface and mesogens are chemically distinct, which adds an enthalpic effect, even though the more interesting interactions are entropic. To raise the structures to the visible regime, while minimizing chemical differences between the particle surface and mesogen, silica particles coated with an α-helical polypeptide have been prepared and dispersed in lyotropic polypeptide LCs. The polypeptide is poly(γ-stearyl-α,l-glutamate) or PSLG. To make the particles easy to manipulate and easy to find, the silica core included superparamagnetic magnetite (Fe O ) and covalently attached dye. Two methods were used to place polypeptides on these magnetic, fluorescent particles: a multistep grafting-to approach in which whole polypeptides were attached and a one-pot grafting-from approach in which the polymerization of the monomers was initiated from the particle surface. These approaches resulted in sparse and dense surface coverages, respectively. The influence of surface curvature and polypeptide molecular weight on the design of sparsely covered particles was investigated using the grafting-to approach. The aggregated grafting-from particles when freshly dispersed in a PSLG/solvent matrix disrupted the orientation of the characteristic cholesteric LC (ChLC) phase directors. In time, the hybrid particles were expelled from some domains, enabling the return of the familiar helical twist of the cholesteric mesophase. The sparsely coated grafting-to hybrid particles when inserted in the PSLG/solvent matrix assembled into stable islet-like formations that could not be disrupted even by an external magnetic field. The bulk particles aligned in chains that were easily manipulated by a magnetic field. These results indicate that polypeptide ChLCs can control and facilitate colloidal assembly of particles with matching surfaces. 3