Covalent quantum dot receptor linkage via the acyl carrier protein for single-molecule tracking, internalization, and trafficking studies

Novel techniques for intraoperative parathyroid gland identification: a comprehensive review

INTRODUCTION

The parathyroid glands (PGs) are critical for calcium regulation and homeostasis. The preservation of PGs during neck surgery is crucial to avoid postoperative hypoparathyroidism. There are no existing guidelines for intraoperative PG identification, and the current approach relies heavily on the experience of the operating surgeon. A technique that accurately and rapidly identifies PGs would represent a useful intraoperative adjunct.

AREAS COVERED

This review aims to assess common dye and fluorescence-based PG imaging techniques and examine their utility for intraoperative PG identification. A literature search of published data on methylene blue (MB), indocyanine green (ICG) angiography, near-infrared autofluorescence (NIRAF), and the PGs between 1971 and 2020 was conducted on PubMed.

EXPERT OPINION

NIRAF and near-infrared (NIR) parathyroid angiography have emerged as promising and reliable techniques for intraoperative PG identification. NIRAF may aid with real-time identification of both normal and diseased PGs and reduce the risk of postoperative complications such as hypocalcemia. Further large prospective multicenter studies should be conducted in thyroid and parathyroid surgical patient populations to confirm the clinical efficacy of these intraoperative NIR-based PG detection techniques.

Azurin/CdSe-ZnS-Based Bio-Nano Hybrid Structure for Nanoscale Resistive Memory Device

In the present study, we propose a method for bio-nano hybrid formation by coupling a redox metalloprotein, Azurin, with CdSe-ZnS quantum dot for the development of a nanoscale resistive memory device. The covalent interaction between the two nanomaterials enables a strong and effective binding to form an azurin/CdSe-ZnS hybrid, and also enabled better controllability to couple with electrodes to examine the memory function properties. Morphological and optical properties were performed to confirm both hybrid formations and also their individual components. Current-Voltage (I–V) measurements on the hybrid nanostructures exhibited bistable current levels towards the memory function device, that and those characteristics were unnoticeable on individual nanomaterials. The hybrids showed good retention characteristics with high stability and durability, which is a promising feature for future nanoscale memory devices.

Enzymatic bioconjugation of nanoparticles: developing specificity and control

Nanoparticles are finding increasing roles in biotechnology for applications as contrast agents, probes, sensors, therapeutics and increasingly new value-added hybrid materials such as molecular logic devices. In most cases these materials must be conjugated to different types of biologicals such as proteins or DNA to accomplish this. However, most traditional methods of bioconjugation result in heterogeneous attachment and loss of activity. Bioorthogonal chemistries and in particular enzymatic labeling chemistries offer new strategies for catalyzing specific biomolecular attachment. We highlight current enzymatic labeling methods available for bioconjugating nanoparticles, some materials they have been used with, and how the resulting bioconjugates were applied. A discussion of the benefits and remaining issues associated with this type of bioconjugation chemistry and a brief perspective on how this field will develop is also provided.

The phosphopantetheinyl transferases: catalysis of a post-translational modification crucial for life

Covering: up to 2013. Although holo-acyl carrier protein synthase, AcpS, a phosphopantetheinyl transferase (PPTase), was characterized in the 1960s, it was not until the publication of the landmark paper by Lambalot et al. in 1996 that PPTases garnered wide-spread attention being classified as a distinct enzyme superfamily. In the past two decades an increasing number of papers have been published on PPTases ranging from identification, characterization, structure determination, mutagenesis, inhibition, and engineering in synthetic biology. In this review, we comprehensively discuss all current knowledge on this class of enzymes that post-translationally install a 4'-phosphopantetheine arm on various carrier proteins.

Green fluorescent protein fused to peptide agonists of two dissimilar G protein-coupled receptors: novel ligands of the bradykinin B2 (rhodopsin family) receptor and parathyroid hormone PTH1 (secretin family) receptor

We hypothesized that peptide hormone sequences that stimulate and internalize G protein-coupled receptors (GPCRs) could be prolonged with a functional protein cargo. To verify this, we have selected two widely different pairs of peptide hormones and GPCRs that nevertheless share agonist-induced arrestin-mediated internalization. For the parathyroid hormone (PTH) PTH1 receptor (PTH1R) and the bradykinin (BK) B2 receptor (B2R), we have designed fusion proteins of the agonists PTH1-34 and maximakinin (MK, a BK homologue) with the enhanced green fluorescent protein (EGFP), thus producing candidate high molecular weight ligands. According to docking models of each hormone to its receptor, EGFP was fused either at the N-terminus (MK) or C-terminus (PTH1-34) of the ligand; the last construction is also secretable due to inclusion of the preproinsulin signal peptide and has been produced as a conditioned medium. EGFP-MK has been produced as a lysate of transfected cells. Using an enzyme-linked immunosorbent assay (ELISA) for GFP, average concentrations of 1.5 and 1670 nmol/L, respectively, of ligand were found in these preparations. The functional properties and potential of these analogs for imaging receptor-expressing cells were examined. Microscopic and cytofluorometric evidence of specific binding and internalization of both fusion proteins was obtained using recipient HEK 293a cells that expressed the cognate recombinant receptor. Endosomal colocalization studies were conducted (Rab5, Rab7, β-arrestin1). Evidence of agonist signaling was obtained (expression of c-Fos, cyclic AMP responsive element (CRE) reporter gene for PTH1-34-EGFP). The constructs PTH1-34-EGFP and EGFP-MK represent bona fide agonists that support the feasibility of transporting protein cargoes inside cells using GPCRs.

Nonendocytic delivery of functional engineered nanoparticles into the cytoplasm of live cells using a novel, high-throughput microfluidic device

The ability to straightforwardly deliver engineered nanoparticles into the cell cytosol with high viability will vastly expand the range of biological applications. Nanoparticles could potentially be used as delivery vehicles or as fluorescent sensors to probe the cell. In particular, quantum dots (QDs) may be used to illuminate cytosolic proteins for long-term microscopy studies. Whereas recent advances have been successful in specifically labeling proteins with QDs on the cell membrane, cytosolic delivery of QDs into live cells has remained challenging. In this report, we demonstrate high throughput delivery of QDs into live cell cytoplasm using an uncomplicated microfluidic device while maintaining cell viabilities of 80-90%. We verify that the nanoparticle surface interacts with the cytosolic environment and that the QDs remain nonaggregated so that single QDs can be observed.

SMAD versus non-SMAD signaling is determined by lateral mobility of bone morphogenetic protein (BMP) receptors

Bone (or body) morphogenetic proteins (BMPs) belong to the TGFβ superfamily and are crucial for embryonic patterning and organogenesis as well as for adult tissue homeostasis and repair. Activation of BMP receptors by their ligands leads to induction of several signaling cascades. Using fluorescence recovery after photobleaching, FRET, and single particle tracking microscopy, we demonstrate that BMP receptor type I and II (BMPRI and BMPRII) have distinct lateral mobility properties within the plasma membrane, which is mandatory for their involvement in different signaling pathways. Before ligand binding, BMPRI and a subpopulation of BMPRII exhibit confined motion, reflecting preassembled heteromeric receptor complexes. A second free diffusing BMPRII population only becomes restricted after ligand addition. This paper visualizes time-resolved BMP receptor complex formation and demonstrates that the lateral mobility of BMPRI has a major impact in stabilizing heteromeric BMPRI-BMPRII receptor complexes to differentially stimulate SMAD versus non-SMAD signaling.

Fluorescent labeling of proteins with amine-specific 1,3,2-(2H)-dioxaborine polymethine dye

A novel water-soluble amine-reactive dioxaborine trimethine dye was synthesized in a good yield and characterized. The potential of the dye as a specific reagent for protein labeling was demonstrated with bovine serum albumin and lysozyme. Its interaction with proteins was studied by fluorescence spectroscopy and gel electrophoresis. The covalent binding of this almost nonfluorescent dye to proteins results in a 75- to 78-fold increase of its emission intensity accompanied by a red shift of the fluorescence emission maximum by 27 to 45 nm, with fluorescence wavelengths of labeled biomolecules being more than 600 nm. The dye does not require activation for the labeling reaction and can be used in a variety of bioassay applications.