Metal-Assembled Collagen Peptide Microflorettes as Magnetic Resonance Imaging Agents.

Magnetic resonance imaging (MRI) is a medical imaging technique that provides detailed information on tissues and organs. However, the low sensitivity of the technique requires the use of contrast agents, usually ones that are based on the chelates of gadolinium ions. In an effort to improve MRI signal intensity, we developed two strategies whereby the ligand DOTA and Gd(III) ions are contained within Zn(II)-promoted collagen peptide () supramolecular assemblies.

Dimeric unnatural polyproline-rich peptides with enhanced antibacterial activity.

We report a dimerization strategy to enhance the antibacterial potency of an otherwise weak cationic amphiphilic polyproline helical (CAPH) peptide. Overall, the dimeric CAPHs were more active against Escherichia coli and Staphylococcus aureus than the monomeric counterpart, reaching up to a 60-fold increase in potency. At their minimum inhibitory concentration (MIC), the dimeric peptides demonstrated no hemolytic activity or bacterial membrane disruption as monitored by β-galactosidase release in E.

Dimeric cationic amphiphilic polyproline helices for mitochondrial targeting.

Purpose: Efficient delivery of therapeutic biopolymers across cell membranes remains a daunting challenge. The development of cell-penetrating peptides (CPPs) has been useful; however, many CPPs are found trapped within endosomes, limiting their use as delivery agents. We optimize a class of CPPs, cationic amphiphilic polyproline helices (CAPHs), for direct transport into cells with mitochondrial localization through dimerization.

Cationic amphiphilic polyproline helix P11LRR targets intracellular mitochondria.

We demonstrate that P11LRR, a recently developed amphiphilic polyproline, cell penetrating agent, is able to locate inside the mitochondria of various cell lines when administrated at high concentrations. Mitochondrial targeting was verified by confocal fluorescence co-localization of P11LRR-fluorescein with Mitotracker Red. Elimination of mitochondrial membrane potential dramatically inhibits the localization of P11LRR to mitochondria.

Cationic amphiphilic polyproline helices: side-chain variations and cell-specific internalization.

Cell-penetrating peptides present an attractive and efficient tool for the delivery of a variety of cell impermeable cargoes across the cellular membrane. Cell-penetrating peptides usually consist of short basic peptide sequences that are internalized by a variety of cell lines. Most cell-penetrating peptides lack cell specificity, however, which greatly limits their use as efficient therapeutic agents.

Assembly of dithiocarbamate-anchored monolayers on gold surfaces in aqueous solutions.

Dithiocarbamates (DTCs) can be formed by the in situ condensation of polar alkylamines with CS 2, and assembled into dithiocarbamate-anchored monolayers (DAMs) on Au substrates in aqueous solutions. Primary and secondary amines can both be used to prepare DTCs, but have significant differences in their reactivities and product stabilities. Ultraviolet absorption spectroscopy provides a convenient method for monitoring in situ DTC formation as well as the formation of potential byproducts.

Probing length effects and mechanism of cell penetrating agents mounted on a polyproline helix scaffold.

Cell penetrating peptides (CPP) displaying a type II polyproline helix backbone of different length and amphiphilic character were synthesized and their cellular uptake was compared. The longer CPP sequence, P14LRR, displayed a 7- to 12-fold higher uptake in MCF-7 cells as compared to its shorter counterpart, P11LRR, and a 35-fold higher uptake as compared to Tatp. These results demonstrate that an increased number of cationic and hydrophobic residues can strongly influence the extent of cellular internalization.