Fluorimetric Reusable Polymeric Sensor for Hydrogen Sulfide Detection.

In this study, with the help of reactive monomers, crosslinkers, and photoinitiator that detect H2S in various matrices, an H2S sensitive fluorescence sensor polymerizes under ultraviolet (UV) light was developed. To this goal, a polymeric membrane was prepared, and the characterization of the membrane was carried out with Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) methods. Afterward, appropriate conditions were identified, the excitation wavelength was determined as 370 nm, and the emission wavelength was determined as 425 nm. It was established that the fluorescence intensity of the prepared polymeric membrane decreased in the presence of H2S. A detailed analysis was executed to determine the sensor's most suitable pH value and time. It was found that the optimum pH was 8.0, and the optimal duration was 15 s. It has been calculated that the linear range of the developed method is 2.19 × 10-8- 6.25 × 10-7 M, and the detection limit (LOD) is 7.37 × 10-9 M. The effect of some possible interfering ions was investigated, and it determined that the sensor had excellent selectivity. In addition, the sensor used to determine H2S can be used at least 100 times. The recovery percentages were 102.1%-103.2%, and 104.6%, using tap water samples. In terms of providing reliable, fast results, high sensitivity, reusable, low cost, and ease of use, the developed fluorimetric sensor, compared to standard methods, has become more advantageous.

Molecularly imprinted nanoparticles with recognition properties towards diphtheria toxin for ELISA applications.

Plastic antibodies can be used for in vitro neutralization of biomacromolecules with different fragments due to their potential in separation, purification, chemical sensor, catalysis and drug production studies. These polymer nanoparticles with binding affinity and selectivity comparable to natural antibodies were prepared using functional monomer synthesis and copolymerization of acrylic monomers via miniemulsion polymerization. As a result, the in vitro cytotoxic effect from diphtheria toxin was reduced by MIPs. In vitro imaging experiments of polymer nanoparticles (plastic antibodies) were performed to examine the interaction of diphtheria toxin with actin filaments, and MIPs inhibited diphtheria toxin damage on actin filaments. The enzyme-linked immunosorbent assay (ELISA) was performed with plastic antibodies labeled with biotin, and it was determined that plastic antibodies could also be used for diagnostic purposes. We report that molecularly imprinted polymers (MIPs), which are biocompatible polymer nanoparticles, can capture and reduce the effect of diphtheria toxic and its fragment A.

Macromolecules can be imprinted by using their fragments as template molecules.MIPs gain an affinity for the template molecule by covalent binding, non-covalent interactions or ligand interactions, as well as the ability to bind, release and recognize the template molecule.The viability of cells treated with DT, NIPs and MIPs was determined by MTT assay.Immunofluorescence staining studies examined structural changes in actin filaments in HUVEC treated with DT, NIPs and MIPs.FA imprinted polymer has the ability to bind whole diphtheria toxin.FA-MIP gave significant results in terms of specificity in ELISA using diphtheria toxin.

Polymeric nanoparticles for selective protein recognition by using thiol-ene miniemulsion photopolymerization.

The fabrication of molecularly imprinted nanoparticles (MIP-NPs) specific for myoglobin by using thiol-ene photopolymerization in miniemulsion was described. Allyl derivatives of phenylalanine as a functional monomer was synthesized and copolymerized with acrylic monomers via miniemulsion polymerization to produce NIP-NPs with approximately 74 nm number average particle diameter. FTIR and 1H-NMR analysis confirmed the synthesis of functional monomer. MIP-NPs were prepared in the existence of myoglobin as a template protein. Morphological investigations exhibited that the particle size of the MIP-NPs, increased compared to the corresponding NIPs and the mean particle diameter by number was measured as 141 nm with narrow distribution. NIP-NPs that were polymerized without myoglobin were found to have less affinity to the target protein. In addition, the rebinding ability of MIP-NPs was much bigger than that of the corresponding NIPs. ELISA results showed that MIPs interact particularly with the myoglobin and show little affinity for BSA in competitive binding experiments.HighlightsAllyl N,N-diallyl phenylalaninate was synthesized as a functional monomer.Imprinted nanoparticles were prepared by using thiol-ene photopolymerization in miniemulsion.The nanoparticles were 141 nm with narrow size distribution.The imprinted nanoparticles showed selectivity toward myoglobin.

A New Fluorescent Sensor for Arsenic(III) Determination in Aqueous Media.

A novel polymeric membrane sensor was developed by using 2-hydroxyethyl acrylate, trimethylolpropane triacrylate, (3-mercaptopropyl)trimethoxysilane, and poly(ethylene glycol)diacrylate for As(III) determination. Various parameters, like the pH, response time, the foreign ions, and concentration effects were investigated for deciding the optimum working conditions of the polymeric sensor. As a result of this investigation, the optimum pH was found to be 2, and the response time was found to be 30 s. The linear range of the sensor was 6.65 × 10-9 - 3.99 × 10-8 mol L-1 (0.50 - 2.99 µg L-1) with a detection limit of 2.33 × 10-9 mol L-1 (0.18 µg L-1). Soy flour and well-water samples were successfully analyzed with the developed sensor. The sensor can be used at least 100 times after regeneration. It could be reused by washing with purified water and showed good stability for 6 months.

Covalent immobilization of acetylcholinesterase on a novel polyacrylic acid-based nanofiber membrane.

In this study, polyacrylic acid-based nanofiber (NF) membrane was prepared via electrospinning method. Acetylcholinesterase (AChE) from Electrophorus electricus was covalently immobilized onto polyacrylic acid-based NF membrane by demonstrating efficient enzyme immobilization, and immobilization capacity of polymer membranes was found to be 0.4 mg/g. The novel NF membrane was synthesized via thermally activated surface reconstruction, and activation with carbonyldiimidazole upon electrospinning. The morphology of the polyacrylic acid-based membrane was investigated by scanning electron microscopy, Fourier Transform Infrared Spectroscopy, and thermogravimetric analysis. The effect of temperature and pH on enzyme activity was investigated and maxima activities for free and immobilized enzyme were observed at 30 and 35°C, and pH 7.4 and 8.0, respectively. The effect of 1 mM Mn2+, Ni2+, Cu2+, Zn2+, Mg2+, Ca2+ ions on the stability of the immobilized AChE was also investigated. According to the Michaelis-Menten plot, AChE possessed a lower affinity to acetylthiocholine iodide after immobilization, and the Michaelis-Menten constant of immobilized and free AChE were found to be 0.5008 and 0.4733 mM, respectively. The immobilized AChE demonstrated satisfactory reusability, and even after 10 consecutive activity assay runs, AChE maintained ca. 87% of its initial activity. Free enzyme lost its activity completely within 60 days, while the immobilized enzyme retained approximately 70% of the initial activity under the same storage time. The favorable reusability of immobilized AChE enables the support to be employable to develop the AChE-based biosensors.

Preparation of biocompatible, UV-cured fumarated poly(ether-ester)-based tissue-engineering hydrogels.

The aim of this study was to develop biodegradable, photo-polymerizable in situ gel-forming systems prepared from a fumaric acid monoethyl ester (FAME) modified poly(lactide-co-glycolide) (PLGA) co-polymer. By reacting lactide and glycolide in the presence of stannous octoate as a catalyst and 2-ethyl,2-hydroxymethyl 1,3-propanediol as an initiator, hydroxyl terminated branched PLGA was synthesized. Afterwards, at room temperature hydroxyl terminated branched PLGA was reacted with fumaric acid monoethyl ester (FAME). N,N'-dicyclohexylcarbodiimide and triethylamine were used as a coupling agent and catalyst, respectively. The gel percentage, equilibrium mass swelling, degradation profile and polymerization kinetics of the hydrogels were investigated. All of the results were influenced by the amount of FAME modified PLGA co-polymer. Biocompatibility of the hydrogels was examined by using MTT cytotoxicity assay. According to the results, hydrogels are biocompatible and cell viability percentage depends on the amount of PLGA co-polymer. While the amount was 15% in hydrogel composition, cell viability was 100%, but after increasing the PLGA co-polymer amount to 30% the viability reduced to 78%.

Photopolymerized injectable RGD-modified fumarated poly(ethylene glycol) diglycidyl ether hydrogels for cell growth.

In this study, photopolymerized hydrogels of fumarated poly(ethylene glycol) diglycidyl-co- poly(ethylene glycol) diacrylate have been synthesized and modified with cell adhesion peptide, Arg-Gly-Asp (RGD). The structural and mechanical properties of the hydrogels are found to be poly(ethylene glycol) diacrylate (PEGDA) dependent. The percentage of gelation is increased from 72 to 89 wt.-% when the amount of the crosslinker co-monomer (PEGDA) in the hydrogel formulation is increased from 20 to 40 wt.-%. In the present case, the equilibrium mass swelling is decreased from 216 to 93%. The viscosities of the uncured formulations have also been measured and likewise, the results were influenced by the increasing amount of PEGDA that reduced the value from 83 to 36 cP. The compressive modulus of the prepared hydrogels was improved with the addition of the PEGDA. Cell growth experiments have been performed by comparing the properties of the hydrogels with and without RGD units. The results show that RGD units enhance the adhesion of cells to the surface of the hydrogels. SEM-EDS studies reveal that nitrogen and calcium are produced on the osteoblast-seeded surface of the scaffold within the culture time period. [Figure: see text].