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A simple and sensitive colorimetric method for the determination of Pb2+ ions in aqueous samples was developed using 1-(2-mercaptoethyl)-1,3,5-triazinane-2,4,6-trione (MTT) functionalized silver nanoparticles (MTT-AgNPs). The Pb2+ ion acted as the metal center of the coordination complex, which formed N–Pb2+–O coordination bonds with the MTT-AgNPs, shortening the interparticle distance, and inducing aggregation of the MTT-AgNPs. This aggregation resulted in a dramatic color change from yellow to dark blue. Using this methodology, the concentration of Pb2+ ions in environmental samples could be quantitatively detected with the naked eye or by using UV-vis spectrometry. Also, we found that the selectivity and sensitivity of detection were noticeably improved in the pH range of 7–8, at which a more obvious color change was observed. The absorption ratios (A625/A395) of the modified AgNP solution exhibited a linear correlation with Pb2+ ion concentrations within the linear range of 0.1–0.6 μg mL−1, and the limits of detection in tap and pond water were 0.02 and 0.06 μg mL−1, respectively. This cost-effective sensing system allows for the rapid and facile determination of Pb2+ ions in aqueous samples. [ABSTRACT FROM AUTHOR]

Antibodies present in mammal's serum are of high relevance for therapeutic purposes, particularly in passive immunization and in the treatment of some chronic diseases. However, their widespread use is still compromised by the requirement of several process steps for their purification and the difficulty in keeping antibodies stable to guarantee their therapeutic efficiency. These challenges significantly contribute to the current high cost of biopharmaceuticals, namely antibodies such as immunoglobulin G (IgG). Accordingly, the development of effective and sustainable purification strategies for antibodies and other biopharmaceuticals is in critical demand to decrease economic, environmental and health burdens. Herein, bio-based and low-cost hybrid alginate–protein cryogel beads were prepared, characterized, and applied as novel adsorbent materials for the purification of IgG from human serum. It is shown that hybrid materials are more efficient than the respective alginate beads since the presence of proteins increases the material selectivity for IgG, which is due to the specific interactions occurring between the target antibody and amino acid residues in the hybrid materials. Several operating conditions, such as pH, adsorption time and serum concentration, were optimized to improve the recovery yield and purity of IgG. Adsorption isotherms were determined to infer the adsorption mechanism of IgG onto the cryogel beads and to determine their adsorption capacity (175 mg of IgG per g of cryogel beads). Under the optimized conditions, IgG can be recovered from the hybrid materials using buffered aqueous solutions, with a purity of 80% and a recovery yield of 91%. The stability and integrity of the antibody are retained after the desorption step. Finally, the regeneration and reuse of the cryogel beads were evaluated, with no losses in the IgG adsorption performance and antibody stability. Although significant efforts have been put on the development of novel affinity ligands to replace the standard chromatographic methods to purify IgG, this work demonstrates the potential of bio-based and low-cost hybrid materials as promising alternatives, in which proteins can be used to improve the material selectivity. [ABSTRACT FROM AUTHOR]

Fe-MOFs were successfully synthesized via a dielectric barrier discharge (DBD) plasma method and applied to methyl orange adsorption. Fe-MOFs were characterized via XRD, SEM, FT-IR, BET and zeta potential analysis. A systematic study was carried out to optimize the synthesis conditions, taking into account the adsorption capacity of the Fe-MOFs. The optimum conditions were determined to be: a discharge time of 80 min; a discharge voltage of 18 kV; a reactant concentration of 10 mg mL−1; and a mass ratio of terephthalic acid to ferric chloride hexahydrate of 1 : 1. Fe-MOFs synthesized under the optimum conditions exhibited an adsorption capacity of 750 mg g−1, at a methyl orange concentration of 100 mg L−1 and with an Fe-MOF dosage of 0.1 g L−1. The kinetic adsorption data showed a good fit to the pseudo-second-order kinetics equation, while the isotherm data were well modeled using the Langmuir equation. Plasma preparation was shown to be an effective method for the preparation of MOFs. [ABSTRACT FROM AUTHOR]