Selective Excitation of the L State of Tryptophan in Collagen-like Peptides Can Reveal the Formation of a Heterotrimer.

Fluorescence emission from tryptophan residues has been often used to probe the protein structure due to its transition dipole moment sensitivity to the local environment. We report the fluorescence study of a collagen-like peptide heterotrimer modified with the tryptophan in the X position (X-Y-Gly) that shows the diminished fluorescence in a homotrimer versus a heterotrimer when the L state is selectively excited. This behavior is only observed in folded peptides, below the helix-to-coil transition temperature, and can be explained by long-range interactions between the tryptophans located on different strands within the triple helix, not by the change in the local environment.

Hybrid peptides as platform for synchronized combination therapy.

Combination therapy, where two or more therapeutic agents are combined to target different cellular pathways, is an effective tool in cancer treatment but often difficult to execute. Here we present the collagen peptide-based platform that allows for synchronous and colocalized cellular delivery of three different agents. The peptide is a hybrid between collagen and cell penetrating peptide (CPP) that assembles into a heterotrimer helix and forms fully organic, high aspect ratio nanoparticles.

Tuning Crystal Structures of Iron-Based Metal-Organic Frameworks for Drug Delivery Applications.

Iron-based metal-organic frameworks (Fe-MOFs) have emerged as promising candidates for drug delivery applications due to their low toxicity, structural flexibility, and safe biodegradation in a physiological environment. Here, we studied two types of Fe-MOFs: MIL-53 and MIL-88B, for in vitro drug loading and releasing of ibuprofen as a model drug. Both Fe-MOFs are based on the same iron clusters and organic ligands but form different crystal structures as a result of two different nucleation pathways.

Higher Order Architecture of Designer Peptides Forms Bioinspired 10 nm siRNA Delivery System.

The higher-order architecture observed in biological systems, like viruses, is very effective in nucleic acid transport. The replications of this system has been attempted with both synthetic and naturally occurring polymers with mixed results. Here we describe a peptide/siRNA quaternary complex that functions as an siRNA delivery system.

The Limitations of Collagen/CPP Hybrid Peptides as Carriers for Cancer Drugs to FaDu Cells.

The in vitro efficacy of cancer prodrugs varies significantly between malignant cell lines. The most commonly identified problems relate to delivery: uptake mechanism, endosomal entrapment, and drug release. Here we present the study of collagen/cell penetrating hybrid (COL/CPP) peptide carriers intended to deliver paclitaxel to the hypopharyngeal carcinoma (FaDu) cells.

The Effect of Pulsed Electric Field on Expression of ECM proteins: Collagen, Elastin, and MMP1 in Human Dermal Fibroblasts.

Electrical stimulation of tissues has many uses in pain management, antibacterial treatment, and wound healing. The electric field stimulates epidermal migration and increases fibroblast cell proliferation. Here we show the effects of electrical field (EF) stimulation of human dermal fibroblasts (HDF) on the expression of collagen, elastin, and collagenase (MMP1; matrix metalloproteinase 1).

Cross-Linked Collagen Gels Using Gold Nanoparticles.

Cross-linking collagen results in the formation of a collagen matrix that is one of the most widely used biomaterials for applications in drug delivery, tissue engineering, molecular scaffolds, and materials for wound dressing. The properties of the collagen matrix depend on the cross-linking strategy employed. Here we describe the preparation and characterization of a nonfibrillar collagen matrix stabilized by cross-linking with tiopronin-protected, 3-4 nm polyvalent gold nanoparticles.

Conjugation of Paclitaxel to Hybrid Peptide Carrier and Biological Evaluation in Jurkat and A549 Cancer Cell Lines.

Paclitaxel (PTX) is one of the most potent cancer drugs; however, its low solubility and strong systemic side effects limit its clinical applications. To overcome these issues, new drug formulations and chemical modifications have been proposed. In this study, we present conjugation of PTX to hybrid collagen-cell penetrating peptide (COL-CPP) carriers.

Immune Response Modulation of Conjugated Agonists with Changing Linker Length.

We report immune response modulation with linked Toll-like receptor (TLR) agonists. Conjugating two agonists of synergistic TLRs induce an increase in immune activity compared to equal molarity of soluble agonists. Additionally, varying the distance between the agonists by changing the linker length alters the level of macrophage NF-κB activity as well as primary bone marrow derived dendritic cell IL-6 production.

Thermoresponsive Collagen/Cell Penetrating Hybrid Peptide as Nanocarrier in Targeting-Free Cell Selection and Uptake.

The effective delivery of therapeutics and imaging agents to a selected group of cells has been at the forefront of biomedical research. Unfortunately, the identification of the unique cell surface targets for cell selection remains a major challenge, particularly if cells within the selected group are not identical. Here we demonstrate a novel approach to cell section relying on a thermoresponsive peptide-based nanocarrier.

Peptide internalization enabled by folding: triple helical cell-penetrating peptides.

Cell-penetrating peptides (CPPs) are known as efficient transporters of molecular cargo across cellular membranes. Their properties make them ideal candidates for in vivo applications. However, challenges in the development of effective CPPs still exist: CPPs are often fast degraded by proteases and large concentration of CPPs required for cargo transporting can cause cytotoxicity.

The microstructure of collagen type I gel cross-linked with gold nanoparticles.

Scanning electron microscopy, transmission electron microscopy, rheometry, and electrochemistry were used to provide insight into the microstructure of collagen type I gel (1%, w/v) modified with the tiopronin-protected (N-(2-mercaptopropionyl)glycine) gold nanoparticles (TPAu), a multivalent crosslinker. The cross-linking reaction, performed via EDC (1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide) coupling, results in compliant, mechanically stable and continuous gels. The gels contain unusual interconnected collagen-TPAu particles.

Collagen cross-linking with Au nanoparticles.

Tiopronin (N-(2-mercaptopropionyl)glycine)-protected gold nanoparticles (TPAu) were cross-linked to collagen via EDC (1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide) coupling. On average, each TPAu forms eight amide bonds with collagen lysine moieties. The resulting gels were studied with environmental SEM, TEM, micro-DSC, and TNBS assay.

Diffusion of 2,2,6,6-tetramethylpiperidine 1-oxyl derivatives of variable hydrophobicity in tropocollagen I solution.

Electrochemical time-of-flight was used to measure the diffusion coefficients of 2,2,6,6-tetramethylpiperidine 1-oxyl derivatives, C(n)TPA, (3 to 7 CH(2) groups), in tropocollagen I solution, as a function of the chain length and the cross-linking with glutaraldehyde. The values of the diffusion coefficient of C(n)TPA in pure aqueous electrolyte follow the Stokes-Einstein law, i.e.

Determination of the capacitance of solid-state potentiometric sensors: An electrochemical time-of-flight method.

A dual microelectrode electrochemical time-of-flight technique in which diffusion flux of Ag+, Cl-, or H+ ions electrochemically produced at a generator electrode is measured by recording potential-time transients with Ag, Ag/AgCl, or iridium oxide potentiometric microsensors, respectively, is developed. The generator and microsensor electrodes are typically spaced by 50-100 microm and are incorporated in the lithographically fabricated thin-layer-type devices. Under conditions of moderate rates of the ion electrogeneration, the potential-time (E-t) transients recorded with the three microsensors show excellent agreement with theory involving linear diffusion equations and the experimentally determined Nernstian slopes of the microsensors.

Electrochemical Time-of-Flight in crosslinked collagen matrix solution: implications of structural changes for drug delivery systems.

Electrochemical Time-of-Flight (ETOF) method was used for the first time to measure the diffusion coefficient of 4-hydroxy-TEMPO, a molecular probe in collagen I matrix solution as a function of its concentration and the extent of crosslinking with glutaraldehyde (GA). The values of the diffusion coefficient were correlated with Circular Dichroism (CD) and viscosity data to assess the changes of the structure of a collagen matrix. The low value of probe diffusion coefficient indicates that the molecular collagen contributes to large diffusion hindrance of the medium.