Zwitterionic Polymer-Decorated Lipid Nanoparticles for mRNA Delivery in Mammalian Cells.

Lipid nanoparticles (LNPs) play a key role in the effective transport of mRNA into cells for protein translation. Despite the stealthiness of poly(ethylene glycol) (PEG) that helps protect LNPs from protein absorption and blood clearance, the generation of anti-PEG antibodies resulting in PEG allergies remains a challenge for the development of an mRNA vaccine. Herein, a non-PEG lipid was developed by conjugating 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) with an antifouling zwitterionic polymer, poly(2-methyacryloyloxyethyl phosphorylcholine) (PMPC), of different chain lengths. The PMPC-LNPs formulated from DPPE-PMPC were spherical (diameter ≈ 144-255 nm), neutral in charge, and stable at 4 °C for up to 28 days. Their fraction of stealthiness being close to 1 emphasized the antifouling characteristics of PMPC decorated on LNPs. The PMPC-LNPs were nontoxic to HEK293T cells, did not induce inflammatory responses in THP-1 cells, and exhibited an mRNA transfection efficiency superior to that of PEG-LNPs. This work demonstrated the potential of the developed zwitterionic polymer-conjugated LNPs as promising mRNA carriers.

Introduction of an Ambient 3D-Printable Hydrogel Ink to Fabricate an Enzyme-Immobilized Platform with Tunable Geometry for Heterogeneous Biocatalysis.

An enzyme-immobilized platform for biocatalysis was developed through 3D printing of a hydrogel ink comprising dimethacrylate-functionalized Pluronic F127 (F127-DMA) and sodium alginate (Alg) with laccase that can be done at ambient temperature, followed by UV-induced cross-linking. Laccase is an enzyme that can degrade azo dyes and various toxic organic pollutants. The fiber diameter, pore distance, and surface-to-volume ratio of the laccase-immobilized and 3D-printed hydrogel constructs were varied to determine their effects on the catalytic activity of the immobilized enzyme. Among the three geometrical designs investigated, the 3D-printed hydrogel constructs with flower-like geometry exhibited better catalytic performance than those with cubic and cylindrical geometries. Once tested against Orange II degradation in a flow-based format, they can be reused for up to four cycles. This research demonstrates that the developed hydrogel ink can be used to fabricate other enzyme-based catalytic platforms that can potentially increase their industrial usage in the future.

Pyrene-Labeled and Quaternized Chitosan: Synthesis, Characterization, and Its Potential Application for Fluorescently Trackable Nucleic Acid Delivery into Cells.

A chitosan derivative (Pyr-CS-HTAP) having pyrene (Pyr) and N-[(2-hydroxyl-3-trimethylammonium)] propyl (HTAP) units conjugated at C6 and C2 positions, respectively, was synthesized and characterized. Dynamic light scattering and scanning electron microscopy revealed that Pyr-CS-HTAP self-assembled into spherical nanoparticles with a hydrodynamic diameter of 211 ± 5 nm and a ζ-potential of +49 mV. The successful binding of Pyr-CS-HTAP with nucleic acid was ascertained by fluorescence resonance energy-transfer analysis and gel electrophoresis. Pyr-CS-HTAP facilitated the cellular uptake of nucleic acid up to 99%. Co-localization analysis using fluorescence microscopy revealed the endosomal escape of the Pyr-CS-HTAP/nucleic acid complexes and the successful release of the nucleic acid cargoes from the polyplexes into the nucleus. It is strongly believed that Pyr-CS-HTAP can potentially be developed into a fluorescently trackable gene delivery system in the future.

Disposable paper-based electrochemical sensor using thiol-terminated poly(2-methacryloyloxyethyl phosphorylcholine) for the label-free detection of C-reactive protein.

A paper-based electrochemical sensor is described that is based on the use of thiol-terminated poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC-SH) that was self-assembled on a gold nanoparticle-modified screen-printed electrode (SPE). The SPE sensor was used for label-free detection of C-reactive protein (CRP). Gold nanoparticles (AuNPs) were first electrodeposited on the SPCE, followed by the self-assembly of PMPC-SH on gold. The electrochemical response of the modified SPE to CRP was measured by differential pulse voltammetry (DPV). If the CRP on the paper device is contacted with Ca (II) ions, the current (measured by using hexacyanoferrate as the electrochemical probe) decreases. The signal drops in the 5 to 5000 ng·mL-1 CRP concentration range, and the lower detection limit (at 3 SD/slope) is 1.6 ng·mL-1. The use of a PMPC-modified surface also reduces the nonspecific adsorption of proteins. The sensor is not interfered by bilirubin, myoglobin and albumin. It was successfully applied to CRP detection in certified human serum. This sensor is applicable as an attractive protocol for an inexpensive, highly sensitive, and disposable material for electrochemical detection of CRP. Graphical abstract Schematic presentation of highly sensitive and disposable paper-based electrochemical sensor using thiol-terminated poly(2-methacryloyloxyethyl phosphorylcholine) in the presence of Ca2+ for the label-free C-reactive protein detection. The current was measured by differential pulse voltammetry.

Gold Nanorods Stabilized by Biocompatible and Multifunctional Zwitterionic Copolymer for Synergistic Cancer Therapy.

A zwitterionic copolymer between methacryloyloxyethyl phosphorylcholine (MPC) and methacrylic acid (MA), PMAMPC is introduced as a potential versatile polymeric stabilizer for gold nanorods (AuNRs). The MA units in the copolymer serve as built-in feature for multiple functionalization, namely introducing additional thiol groups as active sites for binding with the AuNRs and conjugating with doxorubicin (DOX), an anticancer drug via acid-labile hydrazone linkage. The MPC units, on the other hand, provide biocompatibility and antifouling characteristics. The chemically modified PMAMPC can act as an effective stabilizer for AuNRs yielding PMAMPC-DOX-AuNRs with a fairly uniform size and shape with good colloidal stability. In vitro cytotoxicity suggested that PMAMPC can not only improve the AuNRs biocompatibility, but also decrease DOX toxicity to a certain extent. The PMAMPC-DOX-AuNRs were efficiently internalized inside cancer cells and localized in lysosomes, where DOX was presumably acid-triggered released as monitored by confocal laser scanning microscopic analysis and flow cytometry. Furthermore, the combined photothermal-chemo treatment of cancer cells using PMAMPC-DOX-AuNRs exhibited a higher therapeutic efficacy than either single treatment alone. These results suggested that the PMAMPC-DOX-AuNRs could potentially be applied in pH-triggered drug delivery for synergistic cancer therapy.

Antifouling Stripes Prepared from Clickable Zwitterionic Copolymers.

In this study, we have fabricated robust patterned surfaces that contain biocompatible and antifouling stripes, which cause microorganisms to consolidate into bare silicon spaces. Copolymers of methacryloyloxyethyl phosphorylcholine (MPC) and a methacrylate-substituted dihydrolipoic acid (DHLA) were spin-coated onto silicon substrates. The MPC units contributed biocompatibility and antifouling properties, and the DHLA units enabled cross-linking and the formation of robust thin films. Photolithography enabled the formation of 200-µm-wide poly(MPC-DHLA) stripped patterns that were characterized using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and rhodamine 6G staining. Regardless of the spacing between poly(MPC-DHLA) stripes (10, 50, or 100 µm), Escherichia coli rapidly adhered to the bare silicon gaps that lacked the copolymer, confirming the antifouling nature of MPC. Overall, this work provides a surface modification strategy for generating alternating biofouling and nonfouling surface structures that are potentially applicable for researchers studying cell biology, drug screening, and biosensor technology.

Thermoresponsive and Active Functional Fiber Mats for Cultured Cell Recovery.

Thermoresponsive and active functional fiber mats were prepared from random copolymer of poly(pentafluorophenyl acrylate-co-N-isopropylacrylamide) (P(PFPA-co-NIPAM)), which was synthesized by a controlled radical polymerization process based on reversible addition-fragmentation chain transfer (RAFT). As reactive sites, pentafluorophenyl ester (PFP) groups were incorporated in the copolymer to allow for a multiple post-polymerization modification. UV-cross-linkable moieties were first introduced by partially reacting PFP groups in the copolymer with ortho-nitrobenzyl (ONB)-protected diamine. Electrospinning the resulting ONB-containing P(PFPA-co-NIPAM), followed by UV-induced cross-linking, yielded stable cross-linked thermoresponsive PNIPAM-based fiber mats. The remaining PFP active groups on the surface of copolymer fiber mats allowed for further conjugation with an H-Gly-Arg-Gly-Asp-Ser-OH (GRGDS) peptide, a well-known cell adhesive peptide sequence that was selected as a model in order to promote cell growth. At 37 °C, fibroblast cells were found to attach, spread, and proliferate well on the GRGDS-immobilized cross-linked (CL) fiber mat, as opposed to those on the GRGDS-immobilized un-cross-linked (UCL) fiber mat. By decreasing the temperature down to 20 °C, i.e. below the lower critical solution temperature (LCST) of thermoresponsive PNIPAM, cultured cells could easily be released from both GRGDS-immobilized CL and UCL fiber mats, whereas no cells were detached from tissue culture polystyrene (TCPS). These results suggest that the thermosensitive and active functional fiber mat obtained in this research represent an attractive and versatile platform for cultured cell recovery, which is beneficial for tissue engineering applications.

Clickable and Antifouling Platform of Poly[(propargyl methacrylate)-ran-(2-methacryloyloxyethyl phosphorylcholine)] for Biosensing Applications.

A functional copolymer platform, namely, poly[(propargyl methacrylate)-ran-(2-methacryloyloxyethyl phosphorylcholine)] (PPgMAMPC), was synthesized by reversible addition-fragmentation chain-transfer polymerization. In principle, the alkyne moiety of propargyl methacrylate (PgMA) should serve as an active site for binding azide-containing molecules via a click reaction, i.e., Cu-catalyzed azide/alkyne cycloaddition (CuAAC), and 2-methacryloyloxyethyl phosphorylcholine (MPC), the hydrophilic monomeric unit, should enable the copolymer to suppress nonspecific adsorption. The copolymers were characterized using Fourier transform infrared (FTIR) and (1)H NMR spectroscopies. Thiol-terminated, PPgMAMPC-SH, obtained by aminolysis of PPgMAMPC, was immobilized on a gold-coated substrate using a "grafting to" approach via self-assembly. Azide-containing species, namely, biotin and peptide nucleic acid (PNA), were then immobilized on the alkyne-containing copolymeric platform via CuAAC. The potential use of surface-attached PPgMAMPC in biosensing applications was shown by detection of specific target molecules, i.e., streptavidin (SA) and DNA, by the developed sensing platform using a surface plasmon resonance technique. The copolymer composition strongly influenced the performance of the developed sensing platform in terms of signal-to-noise ratio in the case of the biotin-SA system and hybridization efficiency and mismatch discrimination for the PNA-DNA system.

Patterned Poly(acrylic acid) Brushes Containing Gold Nanoparticles for Peptide Detection by Surface-Assisted Laser Desorption/Ionization Mass Spectrometry.

Patterned poly(acrylic acid) (PAA) brushes was successfully generated via photolithography and surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization of acrylic acid as verified by water contact angle measurements and FT-IR analysis. The carboxyl groups of PAA brushes can act as reducing moieties for in situ synthesis of gold nanoparticles (AuNPs), without the use of additional reducing agent. The formation of AuNPs was confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy. The glass surface-modified by PAA brushes and immobilized with AuNPs (AuNPs-PAA) can be used as a substrate for SALDI-MS analysis, which is capable of detecting both small peptides having m/z ≤ 600 (glutathione) and large peptides having m/z ≥ 1000 (bradykinin, ICNKQDCPILE) without the interference from matrix signal suggesting that AuNPs were stably trapped within the PAA brushes and the carboxyl groups of PAA can serve as internal proton source. By employing AuNPs as the capture probe, the AuNPs-PAA substrate can selectively identify thiol-containing peptides from the peptide mixtures with LOD as low as 0.1 and 0.05 nM for glutathione and ICNKQDCPILE, respectively. An ability to selectively detect ICNKQDCPILE in a diluted human serum is also demonstrated. The patterned format together with its high sensitivity and selectivity render this newly developed substrate a potential platform for high-throughput analysis of other biomarkers, especially those with low molecular weight in complex biological samples.

Zwitterionic hydrogel for preserving stability and activity of oxidase enzyme for electrochemical biosensor.

Enzymatic electrochemical biosensor is the most common analytical platform for medical diagnosis. To mimic the biological environment of the enzyme for maintaining the function of biosensor, zwitterionic hydrogels have been recognized as effective matrices for enzymatic immobilization. Herein, a zwitterionic hydrogel derived from a copolymer, poly[2-methacryloyloxyethyl phosphorylcholine (MPC)-co-N-methacryloyloxyethyl tyrosine methylester (MAT)] (PMM) was firstly applied as versatile coating to preserve stability and activity of oxidase enzymes, glucose oxidase (GOx) and lactate oxidase (LOx) for enzymatic electrochemical sensor. A screen-printed carbon electrode (SPCE) was sequentially coated with nitrogen-doped graphene (NDG), oxidase enzyme, and PMM mixed with Ru(II)bpy32+ and (NH4)2S2O8 followed by visible light irradiation for 3 min to induce PMM gelation. Electrochemical detection of glucose and lactate using the modified SPCE was performed via amperometry in the presence of hydrogen peroxide. The activity of both GOx and LOx immobilized on the modified SPCE was well maintained for 49 days at 87 and 80 %, respectively. Additionally, two different electrodes, a screen-printed graphene electrode (SPGE), and a screen-printed silver electrode (SPAgE), similarly modified gave the same satisfactory detection of spiked glucose and lactate in human plasma and sweat with 93-118 % recovery. This indicates the potential of the PMM hydrogel as a universal platform for preservation of enzymes which can be easily fabricated without the need for specific chemical modification of the electrode.

Current significance and future perspective of 3D-printed bio-based polymers for applications in energy conversion and storage system.

The increasing global population has led to a surge in energy demand and the production of environmentally harmful products, highlighting the urgent need for renewable and clean energy sources. In this context, sustainable and eco-friendly energy production strategies have been explored to mitigate the adverse effects of fossil fuel consumption to the environment. Additionally, efficient energy storage devices with a long lifespan are also crucial. Tailoring the components of energy conversion and storage devices can improve overall performance. Three-dimensional (3D) printing provides the flexibility to create and optimize geometrical structure in order to obtain preferable features to elevate energy conversion yield and storage capacitance. It also serves the potential for rapid and cost-efficient manufacturing. Besides that, bio-based polymers with potential mechanical and rheological properties have been exploited as material feedstocks for 3D printing. The use of these polymers promoted carbon neutrality and environmentally benign processes. In this perspective, this review provides an overview of various 3D printing techniques and processing parameters for bio-based polymers applicable for energy-relevant applications. It also explores the advances and current significance on the integration of 3D-printed bio-based polymers in several energy conversion and storage components from the recently published studies. Finally, the future perspective is elaborated for the development of bio-based polymers via 3D printing techniques as powerful tools for clean energy supplies towards the sustainable development goals (SDGs) with respect to environmental protection and green energy conversion.

Construction of Tough Hydrogel Cross-Linked via Ionic Interaction by Protection Effect of Hydrophobic Domains.

Most hydrogels have poor mechanical properties, severely limiting their potential applications, and numerous approaches have been introduced to fabricate more robust and durable examples. However, these systems consist of nonbiodegradable polymers which limit their application in tissue engineering. Herein, we focus on the fabrication and investigate the influence of hydrophobic segments on ionic cross-linking properties for the construction of a tough, biodegradable hydrogel. A biodegradable, poly(γ-glutamic acid) polymer conjugated with a hydrophobic amino acid, l-phenylalanine ethyl ester (Phe), together with an ionic cross-linking group, alendronic acid (Aln) resulting in γ-PGA-Aln-Phe, was initially synthesized. Rheological assessments through time sweep oscillation testing revealed that the presence of hydrophobic domains accelerated gelation. Comparing gels with and without hydrophobic domains, the compressive strength of γ-PGA-Aln-Phe was found to be six times higher and exhibited longer stability properties in ethylenediaminetetraacetic acid solution, lasting for up to a month. Significantly, the contribution of the hydrophobic domains to the mechanical strength and stability of ionic cross-linking properties of the gel was found to be the dominant factor for the fabrication of a tough hydrogel. As a result, this study provides a new strategy for mechanical enhancement and preserves ionic cross-linked sites by the addition of hydrophobic domains. The development of tough, biodegradable hydrogels reported herein will open up new possibilities for applications in the field of biomaterials.

Functionalizable bacterial cellulose composite membrane for guided tissue regeneration.

This research aims to develop guided tissue regeneration (GTR) membranes from bacterial cellulose (BC), a natural polysaccharide-based biopolymer. A double-layered BC composite membrane was prepared by coating the BC membrane with mixed carboxymethyl cellulose/poly(ethylene oxide) (CMC/PEO) fibers via electrospinning. The CMC/PEO-BC membranes were then characterized for their chemical and physical characteristics. The 8 % (wt/v) CMC/PEO (1:1) aqueous solution yielded well-defined electrospun CMC/PEO nanofibers (125 ± 10 nm) without beads. The CMC/PEO-BC membranes exhibited good mechanical and swelling properties as well as good cytocompatibility against human periodontal ligament cells (hPDLs). Its functionalizability via carboxyl entities in CMC was tested using the calcium-binding domain of plant-derived recombinant human osteopontin (p-rhOPN-C122). As evaluated by enzyme-linked immunosorbent assay, a 98-99 % immobilization efficiency was achieved in a concentration-dependent manner over an applied p-rhOPN-C122 concentration range of 7.5-30 ng/mL. The biological function of the membrane was assessed by determining the expression levels of osteogenic-related gene transcripts using quantitative real-time reverse-transcriptase polymerase chain reaction. Mineralization assay indicated that the p-rhOPN-C122 immobilized CMC/PEO-BC membrane promoted hPDLs osteogenic differentiation. These results suggested that the developed membrane could serve as a promising GTR membrane for application in bone tissue regeneration.

Poly(N-isopropylacrylamide)-stabilized gold nanoparticles in combination with tricationic branched phenylene-ethynylene fluorophore for protein identification.

Gold nanoparticles stabilized by thermoresponsive polymer, poly(N-isopropylacrylamide) (PNIPAM-AuNPs) were prepared by surface grafting of thiol-terminated PNIPAM onto citrate-stabilized AuNPs. The color change of the PNIPAM-AuNPs solution from red to blue-purple without precipitation when the solution was heated to 40 °C, above the lower critical solution temperature (LCST) of PNIPAM, indicated the thermoresponsive property of the synthesized AuNPs. PNIPAM-AuNPs were used to detect proteins by chemical nose approach based on fluorescence quenching of fluorophore by AuNPs. An array-based sensing platform for detection of six proteins, namely bovine serum albumin, lysozyme, fibrinogen, concanavalin A, hemoglobin, holo-transferrin human can be successfully developed from the PNIPAM-AuNPs having different molecular weights (4 and 8 kDa) and conformation (varied heat treatment from 25 to 40 °C) in combination with a tricationic branched phenylene-ethynylene fluorophore. From principal component analysis (PCA) followed by linear discriminant analysis (LDA), 100% accuracy of protein classification using a leave-one-out (LOO) approach can be achieved by using only two types of PNIPAM-AuNPs.

Positively charged polymer brush-functionalized filter paper for DNA sequence determination following Dot blot hybridization employing a pyrrolidinyl peptide nucleic acid probe.

As inspired by the Dot blot analysis, a well known technique in molecular biology and genetics for detecting biomolecules, a new paper-based platform for colorimetric detection of specific DNA sequences employing peptide nucleic acid (PNA) as a probe has been developed. In this particular study, a pyrrolidinyl PNA bearing a conformationally rigid d-prolyl-2-aminocyclopentanecarboxylic acid backbone (acpcPNA) was used as a probe. The filter paper was modified to be positively charged with grafted polymer brushes of quaternized poly(dimethylamino)ethyl methacrylate (QPDMAEMA) prepared by surface-initiated polymerization of 2-(dimethylamino)ethyl methacrylate from the filter paper via ARGET ATRP followed by quaternization with methyl iodide. Following the Dot blot format, a DNA target was first immobilized via electrostatic interactions between the positive charges of the QPDMAEMA brushes and negative charges of the phosphate backbone of DNA. Upon hybridization with the biotinylated pyrrolidinyl peptide nucleic acid (b-PNA) probe, the immobilized DNA can be detected by naked eye observation of the yellow product generated by the enzymatic reaction employing HRP-labeled streptavidin. It has been demonstrated that this newly developed assay was capable of discriminating between complementary and single base mismatch targets at a detection limit of at least 10 fmol. In addition, the QPDMAEMA-grafted filter paper exhibited a superior performance to the commercial membranes, namely Nylon 66 and nitrocellulose.

Bacterial cellulose composite hydrogel for pre-concentration and mass spectrometric detection of thiol-containing biomarker.

Simple soaking of bacterial cellulose (BC) membrane in carboxymethyl cellulose (CMC) solution yielded BC/CMC hydrogel having re-swellable property. Then, gold nanoparticles (AuNPs) were embedded in the BC/CMC hydrogel via in situ chemical reduction to form BC/CMC/AuNPs composite hydrogel. It was found that the composite hydrogel exhibited physical/chemical characteristics similar to those of BC. The AuNPs with an average diameter of 13 nm distributed uniformly within the BC/CMC matrix as verified by transmission electron microscopy. The novelty of this work is the application of the BC/CMC/AuNPs composite hydrogel for selective adsorption of an important thiol-containing biomarker of Alzheimer's disease, glutathione (GSH), prior to direct laser desorption/ionization mass spectrometric (LDI-MS) detection. GSH adsorbed in the BC/CMC/AuNPs composite hydrogel showed the high ionization signal in LDI-MS providing a linear range of 50-10,000 nM with a limit of detection as low as 54.1 nM, which is a cut-off level for distinguishing between normal individuals and Alzheimer's patients. It should be emphasized that an additional matrix was not necessary as AuNPs can act as self-matrix for LDI-MS analysis. Furthermore, the BC/CMC/AuNPs composite hydrogel can effectively preconcentrate GSH approximately 10 times upon adsorption allowing for ultrasensitive detection of GSH required for disease diagnosis.

Surface-grafted poly(acrylic acid) brushes as a precursor layer for biosensing applications: effect of graft density and swellability on the detection efficiency.

Carboxyl groups along poly(acrylic acid) (PAA) brushes attached to the surface of a gold-coated substrate served as the precursor moieties for the covalent immobilization of amino-functionalized biotin or bovine serum albumin (BSA) to form a sensing probe for streptavidin (SA) or anti-BSA detection, respectively. Surface-grafted PAA brushes were obtained by acid hydrolysis of poly(tert-butyl acrylate) brushes, formerly prepared by surface-initiated atom transfer radical polymerization of tert-butyl acrylate. As determined by surface plasmon resonance, the PAA brushes immobilized with functionalized biotin or BSA probes not only showed good binding with the designated target analytes but also maintained a high resistance to nonspecific protein adsorption, especially those PAA brushes with a high surface graft density. Although the probe binding capacity can be raised as a function of the graft density of the PAA brushes or the amount of carboxyl groups along the PAA chains, the accessibility of the target analyte to the immobilized probe was limited at the high graft density of the PAA brushes. The effect was far more apparent for the BSA-anti-BSA probe-analyte pair than for the much smaller biotin-SA probe-analyte pair. The impact of the swellability of the PAA brushes, as tailored by the degree of carboxyl group activation, on both the sensing probe immobilization and analyte detection was also addressed. This investigation demonstrated that PAA brushes having a defined graft density have a promising potential as a precursor layer for biosensing applications.

Development of a novel antifouling platform for biosensing probe immobilization from methacryloyloxyethyl phosphorylcholine-containing copolymer brushes.

The immobilization of thiol-terminated poly[(methacrylic acid)-ran-(2-methacryloyloxyethyl phosphorylcholine)] (PMAMPC-SH) brushes on gold-coated surface plasmon resonance (SPR) chips was performed using the "grafting to" approach via self-assembly formation. The copolymer brushes provide both functionalizability and antifouling characteristics, desirable features mandatorily required for the development of an effective platform for probe immobilization in biosensing applications. The carboxyl groups from the methacrylic acid (MA) units were employed for attaching active biomolecules that can act as sensing probes for biospecific detection of target molecules, whereas the 2-methacryloyloxyethyl phosphorylcholine (MPC) units were introduced to suppress unwanted nonspecific adsorption. The detection efficiency of the biotin-immobilized PMAMPC brushes with the target molecule, avidin (AVD), was evaluated in blood plasma in comparison with the conventional 2D monolayer of 11-mercaptoundecanoic acid (MUA) and homopolymer brushes of poly(methacrylic acid) (PMA) also immobilized with biotin using the SPR technique. Copolymer brushes with 79 mol % MPC composition and a molecular weight of 49.3 kDa yielded the platform for probe immobilization with the best performance considering its high S/N ratio as compared with platforms based on MUA and PMA brushes. In addition, the detection limit for detecting AVD in blood plasma solution was found to be 1.5 nM (equivalent to 100 ng/mL). The results have demonstrated the potential for using these newly developed surface-attached PMAMPC brushes for probe immobilization and subsequent detection of designated target molecules in complex matrices such as blood plasma and clinical samples.

Amphiphilic quaternized chitosan: Synthesis, characterization, and anti-cariogenic biofilm property.

Hydrophobized chitosan derivatives, hexyl chitosan (HCS), dodecyl chitosan (DCS), and phthaloyl chitosan (PhCS) of approximately 30 and 50% degree of substitution (%DS) reacted with glycidyltrimethylammonium chloride (GTMAC) to incorporate hydrophilic positively charged groups of N-[(2-hydroxyl-3-trimethylammonium)propyl] and yielded amphiphilic quaternized chitosan derivatives. They can assemble into spherical nanoparticles with a hydrodynamic diameter of ~100-300 nm and positive ζ-potential values (+15 to +56). Their anti-biofilm efficacy was evaluated against the dental caries pathogen, Streptococcus mutans. Among all derivatives, the one having 30%DS of hexyl group and prepared by reacting with 1 mol equivalent of GTMAC (H30CS-GTMAC) showed the best performance in terms of its aqueous solubility, the lowest minimum inhibitory concentration (138 µg/mL) and the minimum bactericidal concentration (275 µg/mL) which are superior to the unmodified chitosan. Its equivalent anti-biofilm efficacy to that of chlorhexidine suggests that it can be a greener antibacterial agent for oral care formulations.

Conductive electrospun composite fibers based on solid-state polymerized Poly(3,4-ethylenedioxythiophene) for simultaneous electrochemical detection of metal ions.

Conductive composite fibers containing poly (3,4-ethylenedioxythiophene) (PEDOT) and silver nanoparticles (AgNPs) were fabricated by emulsion electrospinning of 2,5-dibromo-3,4-ethylenedioxythiophene (DBEDOT) in toluene together with aqueous solution of poly (vinyl alcohol) (PVA) and silver nanoparticles (AgNPs) in the presence of sodium dodecylsulfate followed by heat treatment at 70 °C to convert DBEDOT to conductive PEDOT via solid state polymerization (SSP). The composite fibers were characterized by scanning electron microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy and thermogravimetric analysis. The PEDOT/PVA/AgNPs composite fibers deposited on a screen-printed carbon electrode (SPCE) surface exhibited good electrochemical response and was applied for simultaneous detection of heavy metal ions in a mixture, namely Zn(II), Cd(II), and Pb(II) via square wave anodic stripping voltammetry (SWASV). With added Bi+3 into the detection system, the bismuth film formed on the electrode allows effective alloy formation with the deposited heavy metals obtained upon reduction of the heavy metal ions, the detection of heavy metal ions after stripping was successfully accomplished with a linear range of 10-80 ppb and limits of detections (LOD) of 6, 3 and 8 ppb for Zn(II), Cd(II), and Pb(II), respectively.