Photoacoustic (PA) imaging is an emerging imaging modality that utilizes optical excitation and acoustic detection to enable high resolution at centimeter depths. The development of activatable PA probes can expand the utility of this technology to allow for detection of specific stimuli within live-animal models. Herein, we report the design, development, and evaluation of a series of Acoustogenic Probe(s) for Nitric Oxide (APNO) for the ratiometric, analyte-specific detection of nitric oxide (NO) in vivo. The best probe in the series, APNO-5, rapidly responds to NO to form an N-nitroso product with a concomitant 91 nm hypsochromic shift. This property enables ratiometric PA imaging upon selective irradiation of APNO-5 and the corresponding product, tAPNO-5. Moreover, APNO-5 displays the requisite photophysical characteristics for in vivo PA imaging (e.g., high absorptivity, low quantum yield) as well as high biocompatibility, stability, and selectivity for NO over a variety of biologically relevant analytes. APNO-5 was successfully applied to the detection of endogenous NO in a murine lipopolysaccharide-induced inflammation model. Our studies show a 1.9-fold increase in PA signal at 680 nm and a 1.3-fold ratiometric turn-on relative to a saline control.

Extensive research has gone into deciphering the sequence requirements for peptides to fold into coiled-coils of varying oligomeric states. More recently, additional signals have been introduced within coild-coils to promote...

Mimicking the extracellular matrix (ECM) continues to be a goal in the field of regenerative medicine. Herein, we report a modified trimeric GCN4 coiled‐coil sequence containing three ligands for metal ions specifically positioned for crosslinked assembly (TriCross). In the presence of metal ions, TriCross assembles into a three‐dimensional (3D) matrix with significant cavities to accommodate cells. The matrix was found to be stable in media with serum, and mild removal of the metal leads to disassembly. By assembling TriCross with a suspension of cells in media, the matrix encapsulates cells during the assembly process leading to high cell viability. Further disassembly under mild conditions allows for the release of cells from the scaffold. As such, this peptide‐based material displays many of the characteristics necessary for successful 3D cell culture.

Peptide nanotube biomaterials are attractive for their range of applications. Herein, we disclose the co-assembly of coiled-coil peptides, one with ligands for metal ions that demonstrate hierarchical assembly into nanotubes, with spatial control of the metal-binding ligands. Enhanced stability of the nanotubes to phosphate-buffered saline was successfully accomplished in a metal-dependent fashion, depending on the levels and placement of the ligand-containing coiled-coil peptide. This spatial control also allowed for site-specific labeling of the nanotubes with His-tagged fluorophores through the length of the tubes or at the termini, in a metal-dependent manner.

Hardin s 1968 concept of a "commons dilemma" has received much attention from behavioral scientists concerned with current social and environmental problems that deal with shared resources. The dilemma is that selfish, competitive behavior which appears to be advantageous to the individual actually depletes shared resources to the long-term disadvantage of the group. Various laboratory techniques have been employed to study cooperation and competition in commons dilemma simulations. Two programs are described, which use a multiuser computer system and facilitate the operation of one such simulation procedure.