Extracellular Vesicles and Their Mimetics: A Comparative Study of Their Pharmacological Activities and Immunogenicity Profiles.

Extracellular vesicles (EVs), which are miniaturised carriers loaded with functional proteins, lipids, and nucleic acid material, are naturally secreted by cells and show intrinsic pharmacological effects in several conditions. As such, they have the potential to be used for the treatment of various human diseases. However, the low isolation yield and laborious purification process are obstacles to their translation for clinical use. To overcome this problem, our lab developed cell-derived nanovesicles (CDNs), which are EV mimetics produced by shearing cells through membrane-fitted spin cups. To evaluate the similarities between EVs and CDNs, we compare the physical properties and biochemical composition of monocytic U937 EVs and U937 CDNs. Besides having similar hydrodynamic diameters, the produced CDNs had proteomic, lipidomic, and miRNA profiles with key communalities compared to those of natural EVs. Further characterisation was conducted to examine if CDNs could exhibit similar pharmacological activities and immunogenicity when administered in vivo. Consistently, CDNs and EVs modulated inflammation and displayed antioxidant activities. EVs and CDNs both did not exert immunogenicity when administered in vivo. Overall, CDNs could serve as a scalable and efficient alternative to EVs for further translation into clinical use.

Immuno-Modulatory Effects of Microparticles Formulated from Degradable Polystyrene Analogue.

Environmental accumulation of non-degradable polystyrene (PS) microparticles from plastic waste poses potential adverse impact on marine life and human health. Herein, microparticles from a degradable PS analogue (dePS) are formulated and their immuno-modulatory characteristics are comprehensively evaluated. Both dePS copolymer and microparticles are chemically degradable under accelerated hydrolytic condition. In vitro studies show that dePS microparticles are non-toxic to three immortalized cell lines. While dePS microparticles do not induce macrophage polarization in vitro, dePS microparticles induce in vivo upregulation of both pro-inflammatory and anti-inflammatory biomarkers in immuno-competent mice, suggesting the coexistence of mixed phenotypes of macrophages in the host immune response to these microparticles. Interestingly, on day 7 following subcutaneous in mice, dePS microparticles induce a lower level of several immuno-modulatory biomarkers (matrix metallo-proteinases (MMPs), tumor necrosis factor (TNF-α), and arginase activity) compared to that of reference poly(lactic-co-glycolic acid) microparticles. Remarkably, compared to PS microparticles, dePS microparticles exhibit similar in vitro and in vivo bioactivity while acquiring additional chemical degradability. Overall, this study gains new insights into the host immune response to dePS microparticles and suggests that this dePS analogue might be explored as an alternative material choice for biomedical and consumer care applications.

Backbone degradable poly(acrylic acid) analogue via radical ring-opening copolymerization and enhanced biodegradability.

Degradable poly(acrylic acid) has been prepared via free radical ring-opening copolymerization of tert-butyl acrylate and 2-methylene-1,3-dioxepane followed by tert-butyl deprotection, under acidic conditions. The resulting degradable poly(acrylic acid) analogue possesses ester groups within the backbone, which facilitate environmental hydrolysis into short chain oligomers, which subsequently undergo biodegradation. The degradable poly(acrylic acid) reported displays a significant degree of biodegradability (27.50% in 28 days) under environmental conditions, when compared to a conventional all carbon backbone non-degradable version, which shows no biodegradability.

Elucidating the Role of Interfacial Hydrogen Bonds on Glass Transition Temperature Change in a Poly(Vinyl Alcohol)/SiO2 Polymer-Nanocomposite by Noncovalent Interaction Characterization and Atomistic Molecular Dynamics Simulations.

A thorough experimental investigation of polymer-glass transition temperature (Tg ) is performed on poly(vinyl alcohol) (PVA) and fumed silica nanoparticle (SiNP) composite. This is done together with atomistic molecular dynamics simulations of PVA systems in contact with bare and fully hydroxylated silica. Experimentally, PVA-SiNP composites are prepared by simple solution casting from aqueous solutions followed by its characterization using Fourier-transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA), and dynamic scanning calorimetry (DSC). Both theoretical and experimentally deduced Tg are correlated with the presence of hydrogen bonding interactions involving OH functionality present on the surface of SiNP and along PVA polymer backbone. Further deconvolution of FTIR data show that inter-molecular hydrogen bonding present between PVA and SiNP surface is directly responsible for the increase in Tg . SiNP filler and PVA matrix ratio is also optimized for a desired Tg increase. An optimal loading of SiNP exists, in order to yield the maximum Tg increase arising from the competition between hydrogen bonding and crowding effect of SiNP.

A general strategy for degradable single-chain nanoparticles via cross-linker mediated chain collapse of radical copolymers.

Radical ring-opening copolymerization (rROP) between 2-methylene-1,3-dioxepane (MDO) and methacrylic acid N-hydroxysuccinimide ester (NHSMA) furnishes a reactive polyester-based linear copolymer precursor. Subsequent cross-linker mediated chain collapse affords degradable single-chain nanoparticles (DSCNPs). This methodology is an experimentally robust and straightforward route to main-chain degradable polymeric nanoparticles in the sub-30 nm size range.

Unraveling the History and Revisiting the Synthesis of Degradable Polystyrene Analogues via Radical Ring-Opening Copolymerization with Cyclic Ketene Acetals.

Degradable analogues of polystyrene are synthesized via radical ring-opening (co)polymerization (rROP) between styrene and two cyclic ketene acetals, namely 2-methylene-1,3-dioxepane (MDO) and 5,6-benzo-2-methylene-1,3-dioxepane (BMDO). This approach periodically inserts ester bonds throughout the main chain of polystyrene, imparting a degradation pathway via ester hydrolysis. We discuss the historical record of this approach, with careful attention paid to the conflicting findings previously reported. We have found a common 1H NMR characterization error, repeated throughout the existing body of work. This misinterpretation is responsible for the discrepancies within the cyclic ketene acetal (CKA)-based degradable polystyrene literature. These inconsistencies, for the first time, are now understood and resolved through optimization of the polymerization conditions, and detailed characterization of the degradable copolymers and their corresponding oligomers after hydrolytic degradation.

Nanoparticle-Hydrogel Composites: Concept, Design, and Applications of These Promising, Multi-Functional Materials.

New technologies rely on the development of new materials, and these may simply be the innovative combination of known components. The structural combination of a polymer hydrogel network with a nanoparticle (metals, non-metals, metal oxides, and polymeric moieties) holds the promise of providing superior functionality to the composite material with applications in diverse fields, including catalysis, electronics, bio-sensing, drug delivery, nano-medicine, and environmental remediation. This mixing may result in a synergistic property enhancement of each component: for example, the mechanical strength of the hydrogel and concomitantly decrease aggregation of the nanoparticles. These mutual benefits and the associated potential applications have seen a surge of interest in the past decade from multi-disciplinary research groups. Recent advances in nanoparticle-hydrogel composites are herein reviewed with a focus on their synthesis, design, potential applications, and the inherent challenges accompanying these exciting materials.

Nanoparticle cluster arrays for high-performance SERS through directed self-assembly on flat substrates and on optical fibers.

We demonstrate template-guided self-assembly of gold nanoparticles into ordered arrays of uniform clusters suitable for high-performance SERS on both flat (silicon or glass) chips and an optical fiber faucet. Cluster formation is driven by electrostatic self-assembly of anionic citrate-stabilized gold nanoparticles (~11.6 nm diameter) onto two-dimensionally ordered polyelectrolyte templates realized by self-assembly of polystyrene-block-poly(2-vinylpyridine). A systematic variation is demonstrated for the number of particles (N ≈ 5, 8, 13, or 18) per cluster as well as intercluster separations (S(c) ≈ 37-10 nm). Minimum interparticle separations of <5 nm, intercluster separations of ~10 nm, and nanoparticle densities on surfaces as high as ~7 × 10(11)/in.(2) are demonstrated. Geometric modeling is used to support experimental data toward estimation of interparticle and intercluster separations in cluster arrays. Optical modeling and simulations using the finite difference time domain method are used to establish the influence of cluster size, shape, and intercluster separations on the optical properties of the cluster arrays in relation to their SERS performance. Excellent SERS performance, as evidenced by a high enhancement factor, >10(8) on flat chips and >10(7) for remote sensing, using SERS-enabled optical fibers is demonstrated. The best performing cluster arrays in both cases are achievable without the use of any expensive equipment or clean room processing. The demonstrated approach paves the way to significantly low-cost and high-throughput production of sensor chips or 3D-configured surfaces for remote sensing applications.

Inherently reproducible fabrication of plasmonic nanoparticle arrays for SERS by combining nanoimprint and copolymer lithography.

We present an inherently reproducible route to realizing high-performance SERS substrates by exploiting a high-throughput top-down/bottom-up fabrication scheme. The fabrication route employs self-assembly of amphiphilic copolymers to create high-resolution molds for nanoimprint lithography (NIL) spanning entire 100 mm Si wafers. The nanoporous polymer templates obtained upon NIL are subjected to galvanic displacement reactions to create gold nanorod arrays. Nanorods are subsequently converted to nanodiscs by thermal annealing. The nanodiscs were found to perform as robust SERS substrates as compared with the nanorods. The SERS performance of these substrates and its generality for catering to diverse molecules is demonstrated through the excellent Raman peak resolution and intensity for three different molecules, exhibiting different interaction modes on surface. Numerical simulations using FDTD shows plasmonic coupling between the particles and also brings out the influence due to size distribution. The approach combines distinct advantages of high-precision and repeatability offered by NIL with low-cost fabrication of high-resolution NIL molds by copolymer self-assembly.

Combinatorial synthesis of a triphenylmethine library and their application in the development of surface enhanced Raman scattering (SERS) probes.

The first synthesis of a triphenylmethine (TM) library of compounds and screening of their Surface Enhanced Raman Scattering (SERS) capability was carried out to identify novel Raman reporters with high sensitivity. We identified three novel SERS reporters (B2, B7, and C7) with higher signal intensity than that of commonly used crystal violet (CV). These reporters may find potential applications in developing sensitive SERS based biosensors.

Continuous glucose sensing with fluorescent thin-film hydrogels. 2. Fiber optic sensor fabrication and in vitro testing.

BACKGROUND: There continues to be a need for better sensors for continuous glucose monitoring. We are working on a two-component sensing system based on a viologen boronic acid and a fluorescent dye, which are immobilized in a hydrogel. This system has the potential for further development into a real-time glucose-monitoring device. The current study reports the fabrication of sensors using preformed hydrogels and the first in vitro monitoring of glucose concentrations in a prototype sensor configuration. METHODS: Glucose sensing hydrogels containing a fluorescent dye and viologen boronic acid quencher were preformed in a mold. These preformed hydrogels were then attached to the distal end of a plastic fiber optic cable using different adhesives to prepare the in vitro sensors. These sensors were connected to a flow cell and monitored using a fluorescence spectrometer. The fluorescence emitted by the hydrogel changes depending on the glucose concentration. Hydrogel components were modified in order to optimize the performance of the sensors. RESULTS: A soft tissue adhesive used by veterinarians was found to be an effective adhesive for bonding the hydrogel to the fiber tip. This adhesive did not affect the glucose sensing ability of the hydrogels after fabrication. Several sensors were fabricated with varying composition of sensing elements, and all of them showed stable and reversible glucose response. The glucose signal was found to be stable over months on repeated testing. Glucose sensing studies using the sensors with hydrogels containing different compositions of sensing elements showed that the ratio of dye to quencher is an important parameter in determining the magnitude and linearity of glucose response in the biological range. The response time of the sensor was shown to be dependent on the hydrophilicity of the hydrogels. Modifying the hydrogels with ionic comonomers shortened the response time. CONCLUSIONS: The combination of the anionic dye 2 and viologen-based boronic acid 1 immobilized in a 2-hydroxyethyl methacrylate hydrogel functions well in a fiber optic configuration. This preliminary study suggests that the two-component sensing system has several advantages in terms of stability and ease of fabrication. Improvement of the configuration of the sensor and further development of the sensor towards application for in vitro study are underway.

The interaction of boronic acid-substituted viologens with pyranine: the effects of quencher charge on fluorescence quenching and glucose response.

The fluorescence sensing of several monosaccharides using boronic acid-substituted viologen quenchers in combination with the fluorescent dye pyranine (HPTS) is reported. In this two-component sensing system, fluorescence quenching by the viologen is modulated by monosaccharides to provide a fluorescence signal. A series of viologen quenchers with different charges were prepared and tested for their ability both to quench the fluorescence of HPTS and to sense changes in glucose concentration in aqueous solution at pH 7.4. Both quenching efficiency and sugar sensing were found to be strongly dependent upon viologen charge. The molar ratio between HPTS and each of the viologen quenchers was varied in order to obtain an optimal ratio that provided a fairly linear fluorescence signal across a physiological glucose concentration range. Both the quenching and sugar sensing results are explained by electrostatic interaction between dye and quencher.

Optical glucose detection across the visible spectrum using anionic fluorescent dyes and a viologen quencher in a two-component saccharide sensing system.

A very general system is described in which anionic fluorescent dyes possessing a wide range of absorbance and emission wavelengths are used in combination with a boronic acid-modified viologen quencher to sense glucose at pH 7.4 in buffered aqueous solution. The present study demonstrates this capability with the use of eleven anionic fluorescent dyes of various structural types. Signal modulation occurs as the monosaccharide binds to the viologen quencher and alters its efficiency in quenching the fluorescence of the anionic dyes. The degree of quenching and the magnitude of the glucose signal were found to correlate roughly with the number of anionic groups on the dye. Optimal quencher : dye ratios were determined for each dye to provide a fairly linear signal in response to changes in glucose concentration across the physiological range.