Amplified spontaneous emission and gain in highly concentrated Rhodamine-doped peptide derivative

Bioinspired fluorescence, being widely explored for imaging purposes, faces challenges in delivering bright biocompatible sources. While quite a few techniques have been developed to reach this goal, encapsulation of high-quantum yield fluorescent dyes in natural biological forms suggest achieving superior light-emitting characteristics, approaching amplified spontaneous emission and even lasing. Here we compare gain capabilities of highly concentrated Rhodamine B solutions with a newly synthesized biocompatible peptide derivative hybrid polymer/peptide material, RhoB-PEG1300-F6, which contains the fluorescent covalently bound dye. While concentration quenching effects limit the maximal achievable gain of dissolved Rhodamine B, biocompatible conjugation allows elevating amplification coefficients towards moderately high values. In particular, Rhodamine B, anchored to the peptide derivative material, demonstrates gain of 22–23 cm−1 for a 10−2 M solution, while a pure dye solution possesses 25% smaller values at the same concentration. New biocompatible fluorescent agents pave ways to demonstrate lasing in living organisms and can be further introduced to therapeutic applications, if proper solvents are found.

Pine nut antioxidant peptides ameliorate the memory impairment in a scopolamine-induced mice model via SIRT3-induced synaptic plasticity

This study aimed to investigate the effects of a pine nut albumin hydrolysate (fraction < 3 kDa) and of its short peptide derivative, Trp-Tyr-Pro-Gly-Lys (WYPGK), on synaptic plasticity and memory...

Construction of spatially organized, peptide/peptide derivative containing nanocomposites

The functioning of naturally occurring materials and organisms emerges from the synergistic actions of all involved functional subunits following well-defined spatial hierarchies. Resembling the exquisite structure of biological machinery, the...

Na+/K+-ATPase-associated FXYD3 Protein As An Intracellular Therapeutic Target in Cancer

BackgroundFXYD proteins associate closely with- and protect plasmalemmal Na+/K+-ATPase against oxidative inhibition. One of them, FXYD3, is often overexpressed in cancers, including those of breast and pancreas. Down-regulation of overexpression in MCF-7 breast cancer cells with siRNA augments doxorubicin-induced cytotoxicity. Because down-regulation with siRNA is not readily translated therapeutically, we developed a peptide as an alternative for suppression of FXYD3.MethodsA shortened peptide derivative of the wild-type (WT) FXYD3 protein, FXYD3-pep has the four cysteine residues in the WT protein replaced by serine, which eliminates the WT protein’s protection against oxidative Na+/K+-ATPase inhibition. We exposed human cancer cells to FXYD3-pep and measured cytotoxicity and caspase 3/7 activity with co-exposure to doxorubicin. We also measured effects of the peptide on expression glutathione-S-transferase π (GST-π), implicated in treatment resistance, and on expression of tumor suppressor p53. Selected experiments were performed with parallel FXYD3 suppression with siRNA or FXYD3-pep.ResultsExposure of cells to FXYD3-pep displaced WT FXYD3 from Na+/K+-ATPase. Exposure of MCF-7 breast or pancreatic BxPC-3 cancer cells that highly express FXYD3 to the peptide had little effect alone but combined with doxorubicin it significantly (P < 0.05) increased cytotoxicity. A peptide not mutated to eliminate FXYD3’s protective effect of Na+/K+-ATPase had no effect. FXYD3-pep did not augment doxorubicin’s cytotoxicity against MDA-MB-468 breast and Panc-1 pancreatic cancer cells that have low- or no FXYD3 expression. Cellular FXYD3 expressions was reflected by expression of the α1 Na+/K+-ATPase subunits but not by plasmalemmal Na+/K+-ATPase function. Signals from fluorescently labeled FXYD3-pep were detected in a perinuclear distribution in BxPC-3 cells as reported for overexpressed FXYD3, α- and β Na+/K+-ATPase subunits in cancer. Exposure to FXYD3-pep or to FXYD3 siRNA almost eliminated expression of GST-π. FXYD3-pep alone had no effect on p53 levels but significantly augmented a doxorubicin-induced increase, and, while the peptide alone had no effect on caspase 3/7 activity, it significantly augmented a doxorubicin-induced increase. ConclusionsOverexpressed FXYD3 has intracellular roles beyond its accepted modulation of plasmalemmal Na+/K+-ATPase. These roles can be countered with a membrane-permeable peptide derivative of FXYD3 that suppresses GST-π and enhances chemosensitivity of cancer cells overexpressing FXYD3.

Chemical stimulus-responsive supramolecular hydrogel formation and shrinkage of a hydrazone-containing short peptide derivative

Herein, we describe a short peptide derivative containing a hydrazone bond showing transient hydrogel formation triggered by hydrazone–oxime exchange reaction.

Design and synthesis of a peptide derivative of ametantrone targeting the major groove of the d(GGCGCC)2 palindromic sequence

We report the synthesis of a peptide derivative of antitumor anthraquinones, designed to target GC-rich palindromic sequences. It has micromolar activities on three cancer cell lines and is fifty times less toxic than mitoxantrone on a healthy line.