Directly Quantifiable Biotinylation Using a Water-Soluble Isatoic Anhydride Platform.

Isatoic anhydride (IA) has been shown to be a useful platform for quantifiable bioconjugation. The elaboration of a water-soluble isatoic anhydride-based platform with biotin offers readily quantifiable biotinylation reagents through nondestructive methods of quantification. The incorporation of functionality is directly quantified using the reagent's unique absorbance or fluorescence signature, located outside the biological window. Several biotinylation reagents are prepared with various linker lengths, and the quantification of biotinylated proteins is demonstrated and compared to results from the traditional HABA assay.

Innately Water-Soluble Isatoic Anhydrides with Modulated Reactivities for RNA SHAPE Analysis.

1-Methyl-7-nitroisatoic anhydride (1M7) and 2-methylnicotinic acid imidazolide (NAI) are two of the most commonly applied RNA-SHAPE electrophiles; 1M7 due to its high reactivity and NAI for its solubility and cell permeability. While the addition of a nitro group yields desirable activation of the reagent, it also leads to poorer water solubility. This limited solubility has motivated the development of water-soluble reagents. We present alternative, isatoic anhydride-based reagents possessing variable reactivities that are simultaneously water-soluble. Solubility is gained by using a quaternary ammonium, while modulation of the reactivity is obtained by functionalization of the aryl ring. The syntheses of the reagents are discussed, and the electrophiles are demonstrated to be suitable for use for an in vitro RNA SHAPE experiment when directly compared to 1M7.

Water-Soluble Isatoic Anhydrides: A Platform for RNA-SHAPE Analysis and Protein Bioconjugation.

N-(3-Iodopropyl)isatoic anhydride (IPIA) has been demonstrated to serve as an efficient substrate for the development of an extended bioconjugation platform. Derivatives of IPIA are water-soluble and adaptable and share a common chromophore, rendering them easily quantifiable. We demonstrate the preparation of the readily diversified bioconjugation platform technology and application of the reagents in RNA-SHAPE analysis.

Treatment of pancreatic ductal adenocarcinoma with tumor antigen specific-targeted delivery of paclitaxel loaded PLGA nanoparticles.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDA) remains the most aggressive cancers with a 5-year survival below 10%. Systemic delivery of chemotherapy drugs has severe side effects in patients with PDA and does not significantly improve overall survival rate. It is highly desirable to advance the therapeutic efficacy of chemotherapeutic drugs by targeting their delivery and increasing accumulation at the tumor site. MUC1 is a membrane-tethered glycoprotein that is aberrantly overexpressed in > 80% of PDA thus making it an attractive antigenic target. METHODS: Poly lactic-co-glycolic acid nanoparticles (PLGA NPs) conjugated to a tumor specific MUC1 antibody, TAB004, was used as a nanocarrier for targeted delivery into human PDA cell lines in vitro and in PDA tumors in vivo. The PLGA NPs were loaded with fluorescent imaging agents, fluorescein diacetate (FDA) and Nile Red (NR) or isocyanine green (ICG) for in vitro and in vivo imaging respectively or with a chemotherapeutic drug, paclitaxel (PTX) for in vitro cytotoxicity assays. Confocal microscopy was used to visualize internalization of the nanocarrier in vitro in PDA cells with high and low MUC1 expression. The in vivo imaging system (IVIS) was used to visualize in vivo tumor targeting of the nanocarrier. MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) assay was used to determine in vitro cell survival of cells treated with PTX-loaded nanocarrier. One-sided t-test comparing treatment groups at each concentration and two-way ANOVAs comparing internalization of antibody and PLGA nanoparticles. RESULTS: In vitro, TAB004-conjugated ICG-nanocarriers were significantly better at internalizing in PDA cells than its non-conjugated counterpart. Similarly, TAB004-conjugated PTX-nanocarriers were significantly more cytotoxic in vitro against PDA cells than its non-conjugated counterpart. In vivo, TAB004-conjugated ICG-nanocarriers showed increased accumulation in the PDA tumor compared to the non-conjugated nanocarrier while sparing normal organs. CONCLUSIONS: The study provides promising data for future development of a novel MUC1-targeted nanocarrier for direct delivery of imaging agents or drugs into the tumor microenvironment.

Small-molecule-modified surfaces engage cells through the αvß3 integrin.

Integrins play myriad and vital roles in development and disease. They connect a cell with its surroundings and transmit chemical and mechanical signals across the plasma membrane to the cell's interior. Dissecting their roles in cell behavior is complicated by their overlapping ligand specificity and shared downstream signaling components. In principle, immobilized synthetic peptides can mimic extracellular matrix proteins by supporting integrin-mediated adhesion, but most short peptide sequences lack selectivity for one integrin over others. In contrast, synthetic integrin antagonists can be highly selective. We hypothesized that this selectivity could be exploited if antagonists, when immobilized, could support cellular adhesion and activate signaling by engaging specific cell-surface integrins. To investigate this possibility, we designed a bifunctional (RGD)-based peptidomimetic for surface presentation. Our conjugate combines a high affinity integrin ligand with a biotin moiety; the former engages the α(v)ß(3) integrin, and the latter allows for presentation on streptavidin-coated surfaces. Surfaces decorated with this ligand promote both cellular adhesion and integrin activation. Moreover, the selectivity of these surfaces for the α(v)ß(3) integrin can be exploited to capture a subset of cells from a mixed population. We anticipate that surfaces displaying highly selective small molecule ligands can reveal the contributions of specific integrin heterodimers to cell adhesion and signaling.