Nanomaterials are rich in potential, particularly for the formation of scaffolds that mimic the landscape of the host environment of the cell. This niche arises from the spatial organization of a series of biochemical and biomechanical signals. Self-assembling peptides have emerged as an important tool in the development of functional (bio-)nanomaterials; these simple, easily synthesized subunits form structures which present the properties of these larger, more complex systems. Scaffolds based upon these nanofibrous matrices are promising materials for regenerative medicine as part of a new methodology in scaffold design where a "bottom-up" approach is used in order to simulate the native cellular milieu. Importantly, SAPs hold the potential to be bioactive through the presentation of biochemical and biomechanical signals in a context similar to the natural extracellular matrix, making them ideal targets for providing structural and chemical support in a cellular context. Here, we discuss a new methodology for the presentation of biologically relevant epitopes through their effective presentation on the surface of the nanofibers. Here, we demonstrate that these signals have a direct effect on the viability of cells within a three-dimensional matrix as compared with an unfunctionalized, yet mechanically and morphologically similar system.

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Two multiplex PCR (mPCR) methods were developed to screen large collections of trimethoprim-resistant Escherichia coli isolates for the most prevalent resistance determinants. Five common integron-carried genes (dfrA1, dfrA5, dfrA7, dfrA12 and dfrA17) were selected as PCR targets. Primers and conditions for standard mPCRs and real-time mPCRs were selected and tested. Two protocols using essentially the same primer pairs were established. The standard mPCR protocol also included an internal control targeting the E. coli 16S rRNA gene. Both protocols proved to be sensitive and specific for detection of the five selected genes. Screening of three different collections of clinical urinary and blood isolates (n = 368) with the two multiplex methods revealed that the five dfr genes accounted for 75-86% of trimethoprim resistance. The standard mPCR is useful and accessible for most laboratories, while the real-time mPCR requires additional equipment and expensive reagents, but is very convenient for high-throughput screening of large collections of bacterial isolates.

Self-assembling peptides (SAPs) are a relatively new class of low molecular weight gelators which immobilize their solvent through the spontaneous formation of (fibrillar) nanoarchitectures. As peptides are derived from proteins, these hydrogels are ideal for use as biocompatible scaffolds for regenerative medicine. Importantly, due to the propensity of peptide sequences to act as signals in nature, they are easily functionalized to be cell instructive via the inclusion of bioactive epitopes. In nature, the fibronectin peptide sequence, arginine-glycine-aspartic acid (RGD) synergistically promotes the integrin α 5 β 1 mediated cell adhesion with another epitope, proline-histidine-serine-arginine-asparagine (PHSRN); however most functionalization strategies focus on RGD alone. Here, for the first time, we discuss the biomimetic inclusion of both these sequences within a self-assembled minimalistic peptide hydrogel. Here, based on our work with Fmoc-FRGDF ( N -flourenylmethyloxycarbonyl phenylalanine-arginine-glycine-aspartic acid-phenylalanine), we show it is possible to present two epitopes simultaneously via the assembly of the epitopes by the coassembly of two SAPs, and compare this to the effectiveness of the signals in a single peptide; Fmoc-FRGDF: Fmoc-PHSRN ( N -flourenylmethyloxycarbonyl-proline-histidine-serine-arginine-asparagine) and Fmoc-FRGDFPHSRN ( N -flourenylmethyloxycarbonyl-phenylalanine-arginine-glycine-asparticacid-phenylalanine-proline-histidine-serine-arginine-asparagine). We show both produced self-supporting hydrogel underpinned by entangled nanofibrils, however, the stiffness of coassembled hydrogel was over two orders of magnitude higher than either Fmoc-FRGDF or Fmoc-FRGDFPHSRN alone. In-vitro three-dimensional cell culture of human mammary fibroblasts on the hydrogel mixed peptide showed dramatically improved adhesion, spreading and proliferation over Fmoc-FRGDF. However, the long peptide did not provide effective cell attachment. The results demonstrated the selective synergy effect of PHSRN with RGD is an effective way to augment the robustness and functionality of self-assembled bioscaffolds.