Chemoselective reactions allow near-precision control over the polymer composition and topology to create sequence-controlled polymers with similar secondary and tertiary structures to those found in ...proteins. Dendrimers are recognized as well-defined macromolecules with the potential to mimic protein surface functionality due to the large number of functional groups available at its periphery with the internal structure acting as the support scaffold. Transitioning from using small-molecule dendrimers to dendritic macromolecules will not only allow retention of the high peripheral functionality but also provide an internal scaffold with a desired polymer composition within each generational layer. Here, we exemplify a systematic approach to creating a dendritic macromolecule with the placement of different polymer building blocks in precise locations within the internal structure and the placement of three different amino acid moieties clustered at the periphery. The synthesis of this ABC dendritic macromolecule was accomplished through iterative chemoselective reactions.
There is a strong desire to design and synthesize catalysts that assemble at the oil–water interface to improve the efficiency of biphasic reactions. Anisotropic dumbbell‐shaped bi‐component ...mesoporous carbon–organosilica Janus particles with asymmetric wettability are synthesized through a one‐step compartmentalized growth of a mesoporous organosilica sphere attached to a mesoporous resorcinol–formaldehyde (RF) sphere. A library was prepared of tunable Janus particles possessing diverse hollow structures with various functionalities. As a proof of concept, the Janus particle‐derived catalyst can assemble at the oil–water interface to stabilize Pickering emulsions. Owing to the increased reaction interface area, the Janus catalyst exhibits a more than three‐fold increase in catalytic efficiency compared to the Pt loaded carbon sphere catalyst in aqueous hydrogenation reactions.
Anisotropic dumbbell‐shaped bi‐component mesoporous carbon–organosilica Janus particles with asymmetric wettability were synthesized through a one‐step compartmentalized growth of a mesoporous organosilica sphere attached to a mesoporous resorcinol–formaldehyde sphere. This catalyst assembles at the oil–water interface to stabilize Pickering emulsions, resulting in catalysis efficiency enhancement in aqueous hydrogenation reactions.
Special delivery: An effective group A streptococci vaccine is formed from a delivery device consisting of well‐defined dendritic structures with nanoscale dimensions (see picture). The structures ...are designed to display multiple copies of the minimal B‐cell epitopes, which were in the optimal conformation on the surface of the nanoparticles. The nanoparticles can be administered without the aid of an adjuvant.
Display omitted
•Derivation of log-normal distribution.•Fitting molecular weight distribution.•Determining purity of cyclic polymer.
‘Living’ radical polymerization has opened the way to producing ...complex polymer architectures, including cyclic polymers, dendrimers, stars and many other structures. A major issue in the field of polymer science is the characterization of these polymer products, especially when made to high molecular weights, well beyond the accuracy of NMR or MALDI. Questions of purity arise due to the amount of side products (e.g. dead polymer through termination or cyclic purity). Here, we use the log-normal distribution model to fit distributions of all products to the overall experimental distribution. The fits in all cases were excellent. The log-normal distribution model was simple to implement as it only relies on a two-parameter fit, in which these two parameters, the standard deviation and median, were obtained from the number-average molecular weight and the polydispersity of the molecular weight distribution. This type of analysis can play a role in elucidating the side product distributions, leading to new or modified mechanistic insights.
Layer upon layer: A facile extended Stöber method has been developed for the synthesis of diverse metal–carbon spheres, which includes core–shell‐structured Ag@carbon, rattle‐type Ag,AgBr@meso‐SiO2, ...and yolk–shell‐structured Ag@carbon@meso‐SiO2 (see figure).
Contact Lens Sensors in Ocular Diagnostics Farandos, Nicholas M.; Yetisen, Ali K.; Monteiro, Michael J. ...
Advanced healthcare materials,
04/2015, Letnik:
4, Številka:
6
Journal Article
Recenzirano
Contact lenses as a minimally invasive platform for diagnostics and drug delivery have emerged in recent years. Contact lens sensors have been developed for analyzing the glucose composition of tears ...as a surrogate for blood glucose monitoring and for the diagnosis of glaucoma by measuring intraocular pressure. However, the eye offers a wider diagnostic potential as a sensing site and therefore contact lens sensors have the potential to improve the diagnosis and treatment of many diseases and conditions. With advances in polymer synthesis, electronics and micro/nanofabrication, contact lens sensors can be produced to quantify the concentrations of many biomolecules in ocular fluids. Non‐ or minimally invasive contact lens sensors can be used directly in a clinical or point‐of‐care setting to monitor a disease state continuously. This article reviews the state‐of‐the‐art in contact lens sensor fabrication, their detection, wireless powering, and readout mechanisms, and integration with mobile devices and smartphones. High‐volume manufacturing considerations of contact lenses are also covered and a case study of an intraocular pressure contact lens sensor is provided as an example of a successful product. This Review further analyzes the contact lens market and the FDA regulatory requirements for commercialization of contact lens sensors.
Contact lens sensors have been used as minimally invasive and continuous analytical devices to diagnose glaucoma by measuring intraocular pressure, and diabetes from lachrymal glucose. This Review covers contact lens sensors from concept to market by analyzing detection mechanisms, micro/nanofabrication, powering, readout techniques, and high‐volume manufacturing, supplemented by a case study. A market analysis and FDA approval process are also outlined.
Biological macromolecules such as nucleic acids and proteins are homochiral, display monodisperse chain length with mega, multimillion, molecular weight and encode functions by their precise sequence ...via self-organization. The functions of biological macromolecules are either independent on molecular weight or, like in the case of ribosome, are programmed by the self-organization of their mega molecular weight. In spite of the fact that Staudinger coined the name macromolecule 100 years ago, self-organizable synthetic covalent and supramolecular mega macromolecules exhibiting the symptoms of biological macromolecules started to emerge only recently. This personal perspective will discuss, with examples mostly from our laboratory, methodologies for the synthesis of self-organizable covalent and supramolecular mega macromolecules for which functions are encoded, programmed and perfected via homochiral, sequence-defined and monodisperse components. Methodologies to generate them together with historical developments will be briefly discussed.
Display omitted
•Synthetic self-organizable mega macromolecules.•Sequence-defined encoded extraordinary acceleration of self-organization.•Monodisperse macromolecules by self-interrupted living polymerization.•Isotactic/homochiral dynamic macromolecules by deracemization of atactic/racemic.
•A HNO3 activated biochar was obtained from biochar of Eichhornia crassipes (400 °C).•A rGO/activated biochar nanocomposite was used as carbon paste electrodes modifier.•The developed sensor was ...successfully applied for the paraquat (PQ) determination.•PQ was determined in coconut water, honey, lettuce, lemon and wastewater samples.
A novel electrochemical sensor based on activated biochar (AB4) and reduced graphene oxide (rGO) was developed and tested for detection of paraquat (PQ) in food samples. Precursor biochar was obtained by the pyrolysis of water hyacinth biomass at 400, 500, and 600 °C, followed by a chemical activation step using HNO3 to increase the amount of oxygenated and nitrogenated groups. The modified electrodes (rGO–AB4) were tested in different experimental conditions, and exhibited good response under the optimized conditions, showing linearity from 0.74 to 9.82 μmol L−1 and a limit of detection and limit of quantification of 0.02 μmolL−1 and 0.07 μmol L−1, respectively. Interfering species such as glyphosate caused insignificant changes in the peak current of paraquat, and the selectivity of the method was tested using blank and spiked samples of coconut water, wastewater, honey, lettuce and lemon. Recovery ranged from 87.70±2.07% to 103.80±3.94%.
The chemical composition, size, shape and surface characteristics of nanoparticles affect the way proteins bind to these particles, and this in turn influences the way in which nanoparticles interact ...with cells and tissues. Nanomaterials bound with proteins can result in physiological and pathological changes, including macrophage uptake, blood coagulation, protein aggregation and complement activation, but the mechanisms that lead to these changes remain poorly understood. Here, we show that negatively charged poly(acrylic acid)-conjugated gold nanoparticles bind to and induce unfolding of fibrinogen, which promotes interaction with the integrin receptor, Mac-1. Activation of this receptor increases the NF-κB signalling pathway, resulting in the release of inflammatory cytokines. However, not all nanoparticles that bind to fibrinogen demonstrated this effect. Our results show that the binding of certain nanoparticles to fibrinogen in plasma offers an alternative mechanism to the more commonly described role of oxidative stress in the inflammatory response to nanomaterials.
PDF
