Strategies to encode or label small particles or beads for use in high-throughput screening and bioassay applications focus on either spatially differentiated, on-chip arrays or random distributions of encoded beads. Attempts to encode large numbers of polymeric, metallic or glass beads in random arrays or in fluid suspension have used a variety of entities to provide coded elements (bits)--fluorescent molecules, molecules with specific vibrational signatures, quantum dots, or discrete metallic layers. Here we report a method for optically encoding micrometre-sized nanostructured particles of porous silicon. We generate multilayered porous films in crystalline silicon using a periodic electrochemical etch. This results in photonic crystals with well-resolved and narrow optical reflectivity features, whose wavelengths are determined by the etching parameters. Millions of possible codes can be prepared this way. Micrometre-sized particles are then produced by ultrasonic fracture, mechanical grinding or by lithographic means. A simple antibody-based bioassay using fluorescently tagged proteins demonstrates the encoding strategy in biologically relevant media.

More than 570,000 coronary artery bypass grafts are implanted each year, creating an important demand for small-diameter vascular grafts. For patients who lack adequate internal mammary artery or saphenous vein, tissue-engineered arteries may prove useful. However, the time needed to tissue engineer arteries (7 weeks or more) is too long for many patients. Decellularized cadaveric human arteries are another possible source of vascular conduit, but limited availability and the potential for disease transmission limit their widespread use. In contrast, decellularized tissue-engineered arteries could serve as grafts for immediate implantation, as scaffolds onto which patients' cells could be seeded, or as carriers for genetically engineered cells to aid cell transplantation. The goal of this study was to quantify the effects of decellularization on vascular matrix and mechanical properties. Specifically, we compared cellular elimination, extracellular matrix retention, and mechanical characteristics of porcine carotid arteries before and after treatment with three decellularization methods. In addition, for the first time, tissue-engineered arteries were decellularized. Decellularized native arteries were also used as a scaffold onto which vascular cells were seeded. These studies identified a decellularization method for native and engineered arteries that maximized cellular elimination, without greatly compromising mechanical integrity. We showed that engineered tissues could be decellularized, and demonstrated the feasibility of reseeding decellularized vessels with vascular cells.

The purpose of the Taking Design Thinking to Schools Research Project was to extend the knowledge base that contributes to an improved understanding of the role of design thinking in K‐12 classrooms. The ethnographic qualitative study focused on the implementation of an interdisciplinary design curriculum by a team of university instructors in a public charter school. Three questions framed the study. How did students express their understanding of design thinking classroom activities? How did affective elements impact design thinking in the classroom environment? How is design thinking connected to academic standards and content learning in the classroom?

. Engineering skeletal myoblasts: roles of three-dimensional culture and electrical stimulation.

Reproducible research is the bedrock of experimental science. To enable the deployment of large-scale proteomics, we assess the reproducibility of mass spectrometry (MS) over time and across instruments and develop computational methods for improving quantitative accuracy. We perform 1560 data independent acquisition (DIA)-MS runs of eight samples containing known proportions of ovarian and prostate cancer tissue and yeast, or control HEK293T cells. Replicates are run on six mass spectrometers operating continuously with varying maintenance schedules over four months, interspersed with~5000 other runs. We utilise negative controls and replicates to remove unwanted variation and enhance biological signal, outperforming existing methods. We also design a method for reducing missing values. Integrating these computational modules into a pipeline (ProNorM), we mitigate variation among instruments over time and accurately predict tissue proportions. We demonstrate how to improve the quantitative analysis of large-scale DIA-MS data, providing a pathway toward clinical proteomics.

No abstract

The biochemical complexity of ant venoms, associated with an enormous ecological and taxonomic diversity, suggests that stinging ant venoms constitute a promising source of bioactive molecules that could be exploited in the search for novel drug and biopesticide leads.

The L-to-D-peptide isomerase from the venom of the platypus (Ornithorhyncus anatinus) is the first such enzyme to be reported for a mammal. In delineating its catalytic mechanism and broader roles in the animal, its substrate specificity was explored. We used N-terminal segments of defensin-like peptides DLP-2 and DLP-4 and natriuretic peptide OvCNP from the venom as substrates. The DLP analogues IMFsrs and ImFsrs (srs is a solubilizing chain; lowercase letters denote D-amino acid) were effective substrates for the isomerase; it appears to recognize the N-terminal tripeptide sequence Ile-Xaa-Phe-. A suite of 26 mutants of these hexapeptides was synthesized by replacing the second residue (Met) with another amino acid, viz. Ala, ␣-aminobutyric acid, Ile, Leu, Lys, norleucine, Phe, Tyr, and Val. It was shown that mutant peptides incorporating norleucine and Phe are substrates and exhibit L-or D-amino acid isomerization, but mutant peptides that contain residues with shorter, ␤-branched or long side chains with polar terminal groups, viz. Ala, ␣-aminobutyric acid, Ile, Val, Leu, Lys, and Tyr, respectively, are not substrates. It was demonstrated that at least three N-terminal amino acid residues are absolutely essential for L-to D-isomerization; furthermore, the third amino acid must be a Phe residue. None of the hexapeptides based on LLH, the first three residues of OvCNP, were substrates. A consistent 2-base mechanism is proposed for the isomerization; abstraction of a proton by 1 base is concomitant with delivery of a proton by the conjugate acid of a second base.Bioactive peptides that contain D-amino acid residues occur in lower animals such as snails (1, 2), crustaceans (3), and spiders (4, 5) and among more the highly evolved amphibians, frogs (6, 7). In mammals, to date, they have only been reported for the Australian duck-bill platypus (Ornithorhyncus anatinus) (8). These peptides are invariably components of venoms. In all cases there is only one D-amino acid residue present, and it is near the N terminus in the case of the frog and platypus peptides, but it is near the C terminus in the case of spider venom peptides. In the latter, the third amino acid residue from the C terminus is in the D-form (4, 9). In all cases the D-amino acid residues are the result of post-translational modification of the original all-L-peptide (10, 11). The stereo-isomerization is catalyzed by a specific enzyme called peptidyl aminoacyl L/Disomerase or, as we use hereafter, peptide isomerase.The crude venom of Australian male platypus contains ϳ50 peptides (12); among them are a C-type natriuretic peptide (OvCNP) and defensin-like peptides (DLPs).2 Both OvCNP and one of the DLPs exist in two isomeric forms; OvCNP exists in an a and a b form with OvCNPa consisting of all L-amino acids, whereas OvCNPb has a D-Leu in position 2 (12). Similarly, DLP-4 consists of all L-amino acids, whereas DLP-2 contains D-Met at position 2 (13). The presence of the L-to-D-amino acid residue isomerase has been reported in several cases where pepti...