Integrated Tyramide and Polymerization-Assisted Signal Amplification for a Highly-Sensitive Immunoassay

A novel strategy for ultrasensitive detection of model protein based on the integration of tyramide signal amplification (TSA) and polymerization-assisted signal amplification was proposed. The surface-initiated atom transfer radical polymerization (SI-ATRP) of glycidyl methacrylate (GMA) was triggered by the initiator-coupled protein immobilized on the electrode surface through sandwiched immunoreactions. Growth of long chain polymeric materials provided numerous epoxy groups for subsequent coupling of horseradish peroxidase (HRP), which in turn significantly increased the loading of quantum dots (QDs) labeled tyramide in the presence of hydrogen peroxide. As a result, electrochemiluminescence (ECL) and square-wave voltammetric (SWV) measurements showed 9.4- and 10.5-fold increase in detection signal in comparison with the unamplified method, respectively. To demonstrate the feasibility of this approach, human immunoglobulin G antigen (IgG) as a model target protein was employed and the detection limits were 0.73 and 0.09 pg mL^–1 for ECL and SWV, respectively. The results showed that sensitivity of the presented immunoassay significantly increased by one-order of magnitude and offered great application promises in providing a sensitive, specific, and potent method for biological detection

Nature-Inspired DNA Nanosensor for Real-Time <i>in Situ</i> Detection of mRNA in Living Cells

Rapid and precise <i>in situ</i> detection of gene expressions within a single cell is highly informative and offers valuable insights into its state. Detecting mRNA within single cells in real time and nondestructively remains an important challenge. Using DNA nanotechnology and inspired by nature’s many examples of “protective-yet-accessible” exoskeletons, we designed our mRNA nanosensor, nano-snail-inspired nucleic acid locator (nano-SNEL), to illustrate these elements. The design of the nano-SNEL is composed of a sensory molecular beacon module to detect mRNA and a DNA nanoshell component, mimicking the functional anatomy of a snail. Accurate and sensitive visualization of mRNA is achieved by the exceptional protection conferred by the nanoshell to the sensory component from nucleases-mediated degradation by approximately 9–25-fold compared to its unprotected counterpart. Our nano-SNEL design strategy improved cell internalization is a demonstration of accurate, dynamic spatiotemporal resolved detection of RNA transcripts in living cells

Self-Assembly of a Diblock Copolymer with Pendant Disulfide Bonds and Chromophore Groups: A New Platform for Fast Release

An amphiphilic block copolymer comprising poly­(ethylene glycol) (PEG) and poly­(2-(methacryloyl)­oxyethyl-2′-hydroxyethyl disulfide) (PMAOHD) blocks was synthesized by atom transfer radical polymerization (ATRP). Pyrenebutyric acid was conjugated to the block copolymer by esterification, and a block copolymer with pendant disulfide bonds and pyrenyl groups (PEG-<i>b</i>-P­(MAOHD-<i>g</i>-Py)) was obtained. ¹H NMR and gel permeation chromatography (GPC) results demonstrated the successful synthesis of the block copolymer. The cleavage of the disulfide bonds and the degrafting of the pyrenyl groups were investigated in THF and a THF/methanol mixture. Fluorescence spectroscopy, GPC, and ¹H NMR results demonstrated fast cleavage of the disulfide bonds by Bu₃P in THF. Fluorescence results showed the ratio of the intensity of the excimer peak to the monomer peak decreased rapidly within 20 min. GPC traces of the block copolymer moved to a long retention time region after addition of Bu₃P, indicating the cleavage of the disulfide bonds and the degrafting of the pyrenyl groups. PEG-<i>b</i>-P­(MAOHD-<i>g</i>-Py) can self-assemble into micelles with poly­(MAOHD-<i>g</i>-Py) cores and PEG coronae in a mixture of methanol and THF (9:1 by volume). The dissociation of the micelles in the presence of Bu₃P was investigated. After cleavage of the disulfide bonds in the micellar cores, a pyrene-containing small molecular compound and a block copolymer with pendant thiol groups were produced. Transmission electron microscopy (TEM), dynamic light scattering (DLS), and ¹H NMR were employed to track the dissociation of the polymeric micelles. All the techniques demonstrated the dissociation of the micelles and the fast release of pyrenyl groups from the micelles

Robust Amidation Transformation of Plant Oils into Fatty Derivatives for Sustainable Monomers and Polymers

Sustainable fuels, chemicals, and materials from renewable resources have recently gained tremendous momentum in a global scale, although there are numerous nontrivial hurdles for making them more competitive with petroleum counterparts. We demonstrate a robust strategy for the transformation of plant oils into polymerizable monomers and thermoplastic polymer materials. Specifically, triglycerides were converted into <i>N</i>-hydroxyalkyl fatty amides with the aid of amino alcohols via a mild base-catalyzed amidation process with nearly quantitative yields without the use of column chromatography and organic solvents. These fatty amides were further converted into a variety of methacrylate monomers, cyclic norbornene monomers and imino ether monomers. Representative polymers from selected monomers exhibit drastic different physical properties with subtle structural variations, highlighting the potential of this particular amidation reaction in the field of biomass transformation

Self-Assembly of Monotethered Single-Chain Nanoparticle Shape Amphiphiles

Shape amphiphiles with distinct shapes and amphiphilic properties can be used as fundamental building blocks in the fabrication of novel structures and advanced materials. In this research synthesis and self-assembly of monotethered single-chain nanoparticle shape amphiphiles are reported. Poly­(2-(dimethylamino)­ethyl methacrylate)-<i>block</i>-polystyrene (PDMAEMA-<i>b</i>-PS) was synthesized by two-step reversible addition–fragmentation chain transfer (RAFT) polymerization. The PDMAEMA blocks were intramolecularly cross-linked by 1,4-diiodobutane (DIB) at significantly low concentrations, and PS-tethered PDMAEMA single-chain nanoparticles were prepared. Gel permeation chromatograph, ¹H NMR and transmission electron microscopy results all indicated successful synthesis of the structures. The controlled self-assembly of the shape amphiphiles in selective solvents was investigated. Depending on the size of the single-chain nanoparticles, the shape amphiphiles self-assemble into strawberry-like micelles, a structure with single-chain nanoparticles in the corona and PS in the core, or vesicles in aqueous solutions. Similar to the self-assembled structures in aqueous solution, the morphology of the aggregates in methanol changes from micellar structure to vesicular structure with the decrease of the PDMAEMA single-chain nanoparticles size. In cyclohexane, the shape amphiphiles self-assemble into bunchy micelles with single-chain nanoparticles in the cores and linear PS in the coronae

Photodegradable Dynamic Polyurethane Networks via Dithioacetals

Cross-linked polymer networks fabricated with renewable resources are being actively sought for tackling the resource crisis. Meanwhile, dynamic networks with cleavable groups further promote recycling and degradation. Herein, a vanillin-derived trifunctional compound containing a dithioacetal moiety was found to be an efficient cross-linker for making polyurethane networks (PUNs) with coexisting dynamic dithioacetal and phenolic carbamate groups. The dual-dynamic PUNs were featured with faster stress relaxation over monodynamic PUNs, good stability in acidic environments, and thermally promoted recyclability. Moreover, photocleavage of the dithioacetal groups was realized under blue light (460 nm) to trigger the network degradation. This work represents an appealing molecular design to realize photodegradable dynamic networks via introducing dithioacetals, which could potentially be degraded under different wavelengths

Development of Core–Shell Nanostructures by In Situ Assembly of Pyridine-Grafted Diblock Copolymer and Transferrin for Drug Delivery Applications

We previously reported the coassembly of various proteins with poly­(4-vinylpyridine) (P4VP) to form core–shell nanoparticles (CSNPs). However, P4VP suffers from its cytotoxicity and in vivo toxicity, which prohibit it from many potential biomedical applications. Here, pyridine-grafted diblock copolymer poly­(caprolactone-<i>graft</i>-pyridine)-<i>block</i>-poly­(caprolactone) [P­(CL-<i>g</i>-Py)-<i>b</i>-PCL] was prepared through a combination of ring-opening polymerization and Cu­(I) catalyzed azide–alkyne cycloaddition reaction. CSNPs could be readily constructed by the self-assembly of transferrin (Tf) and P­(CL-<i>g</i>-Py)-<i>b</i>-PCL, which showed a narrower range of particle sizes, improved stability, and higher loading capacity for anticancer drug doxorubicin (DOX), compared with similar particles prepared from the coassembly of Tf and P4VP. Additionally, the drug-loaded Tf/P­(CL-<i>g</i>-Py)-<i>b</i>-PCL CSNPs could effectively target MCF7 cancer cells via the binding of Tf to transferrin receptors (TfR)

Bioinspired High Resilient Elastomers to Mimic Resilin

Natural resilin possesses outstanding mechanical properties, such as high strain, low stiffness, and high resilience, which are difficult to be reproduced in synthetic materials. We designed high resilient elastomers (HREs) with a network structure to mimic natural resilin on the basis of two natural abundant polymers, stiff cellulose and flexible polyisoprene. With plasticization via mineral oil and mechanical cyclic tensile deformation processing, HREs show ultrahigh resilience, high strain, and reasonable tensile strength that closely mimic natural resilin. Moreover, the mechanical properties of HREs can be finely tuned by adjusting the cellulose content, providing the opportunity to synthesize high resilient elastomers that mimic different elastic proteins, such as elastin

Collision and Oxidation of Single LiCoO₂ Nanoparticles Studied by Correlated Optical Imaging and Electrochemical Recording

Electrochemists have witnessed the rapid development of single nanoparticle collision (SNC) in the past decade as a powerful technology to study the electrochemical activity of single nanoparticles (NPs). One of the ultimate goals of SNC is to build the structure–activity relationship in a bottom-up way, which requires the correlation between the electrochemical activity and the morphology/structure of the same individual. In the present work, we demonstrated the capability of combining surface plasmon resonance microscopy (SPRM) and conventional electrochemical recordings to correlate the size and activity of single LiCoO₂ NPs. Electrochemical recordings provided the rate and amount of electron transfer associated with a single LiCoO₂ NP during its collision onto the electrode. SPRM measured the size and the location of the collision of the very same individual, which further allowed for the morphology characterization with scanning electron microscopy. The present work was the first attempt to correlate the electrochemical activity and the morphology of single Li-ion storage NPs during collision events, which not only expanded the SNC technology to study versatile electro-active cathode and anode nanomaterials in different kinds of batteries, but also paved a way toward the structure–activity relationship of Li-ion storage nanomaterials with significant implications for Li-ion batteries

Inhibition of Proliferation and Induction of Autophagy by Atorvastatin in PC3 Prostate Cancer Cells Correlate with Downregulation of Bcl2 and Upregulation of miR-182 and p21

<div><p>The epidemiologic association between statin use and decreased risk of advanced prostate cancer suggests that statins may inhibit prostate cancer development and/or progression. Studies were performed to determine the effects of a model statin, atorvastatin (ATO), on the proliferation and differentiation of prostate cancer cells, and to identify possible mechanisms of ATO action. ATO inhibited the <i>in vitro</i> proliferation of both LNCaP and PC3 human prostate cancer cells in a dose- and time-dependent fashion. The greater inhibitory activity of ATO in PC3 cells was associated with induction of autophagy in that cell line, as demonstrated by increased expression of LC3-II. miR-182 was consistently upregulated by ATO in PC3 cells, but not in LNCaP cells. ATO upregulation of miR-182 in PC3 cells was p53-independent and was reversed by geranylgeraniol. Transfection of miR-182 inhibitors decreased expression of miR-182 by >98% and attenuated the antiproliferative activity of ATO. miR-182 expression in PC3 cells was also increased in response to stress induced by serum withdrawal, suggesting that miR-182 upregulation can occur due to nutritional stress. Bcl2 and p21 were identified to be potential target genes of miR-182 in PC3 cells. Bcl2 was downregulated and p21 was upregulated in PC3 cells exposed to ATO. These data suggest that miR-182 may be a stress-responsive miRNA that mediates ATO action in prostate cancer cells.</p></div