Isolation and antimalarial activity of peroxydisulfate oxidation products of primaquine

Five compounds formed by peroxydisulfate oxidation of primaquine were isolated using chromatographic methods and evaluated for antimalarial activity in vitro. One compound 6-methoxy-5,8 bis(4′-amino-1′-methylbutylamino)quinoline [P₁] was found to have good gametocytocidal activity against Plasmodium yoelli infected mice at 10 mg kg⁻¹ dose in vivo.     

Electrochemiluminescence of peroxydisulfate enhanced by L-cysteine film for sensitive immunoassay

A novel label free electrochemiluminescence (ECL) immunosensor based on the ECL of peroxydisulfate solution for detection of α-1-fetoprotein (AFP) has been developed. For this proposed immunosensor, L-cysteine was firstly electrodeposited on the gold electrode surface, which promoted the electron transfer and largely enhanced the ECL of peroxydisulfate solution. Subsequently, gold nanoparticles (nano-Au) were assembled onto the L-cysteine film modified electrode to improve the absorption capacity of antibody and further amplify the ECL signal. Then, antibody was immobilized onto the electrode through nano-Au. At last bovine serum albumin (BSA) was employed to block the nonspecific binding sites. As a result, a novel ECL immunosensor was firstly obtained by applying the ECL of peroxydisulfate solution without conventional luminescent reagents. The AFP was determined in the range of 0.01-100 ng mL(-1), with a low detection limit of 3.3 pg mL(-1) (S/N=3). The proposed ECL immunosensor provides a rapid, simple, and sensitive immunoassay protocol for protein detection, which might hold a promise for clinical application. Moreover, this work would open up a new field in the application of peroxydisulfate solution ECL for highly sensitive bioassays.     

Graft copolymerization of ethylacrylate onto xanthan gum, using potassium peroxydisulfate as an initiator

Graft copolymer of xanthan gum (XG) and ethylacrylate (EA) has been synthesized by free radical polymerization using potassium peroxydisulfate (KPS) as an initiator in an air atmosphere. The grafting parameters, i.e. grafting ratio and efficiency decrease with increase in concentration of xanthan gum from 0.050 mg/25 mL to 0.350 mg/25 mL, but these grafting parameters increase with increase in concentration of ethylacrylate from 9 × 10⁻² to 17 × 10⁻² ML⁻¹, and KPS from 15 × 10⁻³ to 35 × 10⁻³ ML⁻¹. The graft copolymer has been characterized by FTIR, XRD, TGA and SEM analysis. The grafted copolymer was also evaluated as efficient Zn²⁺ metal binder. The grafted copolymer shows improvement in the stability, solubility as well as their sorbing capacity. Thus graft copolymer formed could find applications in metal ion removal and in drug delivery.     

Bi-enzyme synergetic catalysis to in situ generate coreactant of peroxydisulfate solution for ultrasensitive electrochemiluminescence immunoassay

A novel electrochemiluminescence (ECL) immunosensor for ultrasensitive detection of α-1-fetoprotein (AFP) was designed based on the in situ bi-enzymatic reaction to generate coreactant of peroxydisulfate for signal amplification. In this work, AuNPs were electrodeposited on the glassy carbon electrode (GCE) surface, which promoted the electron transfer. Then, L-cysteine and another layer of AuNPs were, respectively assembled onto the modified electrode surface, which formed the multilayer films for amplifying the ECL signal of peroxydisulfate and immobilizing antibody. At last, glucose oxidase (GOD) and horseradish peroxidase (HRP) were employed to block the nonspecific binding sites. When proper amounts of glucose were added in the detection solution, GOD catalyzed the oxidation of glucose to generate H(2)O(2), which could be further catalyzed by HRP to generate O(2) for the signal amplification. The linear range for AFP detection was 0.001-100 ng mL(-1), with a low detection limit of 3.3 × 10(-4) ng mL(-1). The novel strategy has the advantages of simplicity, sensitivity, good selectivity and reproducibility which might hold a new promise for highly sensitive bioassays applied in clinical detection.     

Highly amplified electrochemiluminescence of peroxydisulfate using bienzyme functionalized palladium nanoparticles as labels for ultrasensitive immunoassay

An immunosensor based on the electrochemiluminescence (ECL) of peroxydisulfate was firstly proposed by coupling the cooperation of two enzymes to in situ generate coreactant with palladium nanoparticles (PdNPs) as catalyst for the ECL reaction. PdNPs were previously synthesized, which successfully attached to functional carbon nanotubes (FCNTs), to bind the secondary antibody and bienzyme (horseradish peroxidase and glucose oxidase). Then the prepared bioconjugates were introduced to the electrode via sandwich immunoreactions. Accordingly, a dramatically amplified ECL signal was obtained for that GOD catalyzed glucose to produce H(2)O(2) which was subsequently reduced by HRP to in situ generate O(2), then PdNPs as catalyst for the ECL reaction of peroxydisulfate/O(2). The present immunosensor was used to detect α-1-fetoprotein (AFP) and showed a wide linear range of 1×10(-5)-100ngmL(-1), with a low detection limit of 3.3fgmL(-1)(S/N=3). This new signal amplification strategy for preparation of the ECL immunosensor could be easily realized and has a potential application in ultrasensitive bioassays.     

31P-NMR study of turnip seed germination and sprout growth inhibition by peroxydisulfate ion

³¹P-NMR was used to study turnip seeds (Brassica rapa L.) incubated in 0.05 M K₂SO₄ solution, where they germinate and grow normally, and in 0.05 M K₂S₂O₈ (potassium peroxydisulfate), where they germinate but do not grow. With ³¹P-NMR it is possible to measure cytoplasmic and vacuolar pH, to identify phosphorus metabolites and to measure their relative concentrations in vivo. Results show a nearly constant vacuolar pH during germination and growth in K₂SO₄ contrasted with a steady decrease in vacuolar pH for seeds exposed to K₂S₂O₈. Cytoplasmic pH decreases during germination and then stabilizes during growth in K₂SO₄; it follows the same course during germination but then drops precipitously in K₂S₂O₈. The quantity of dissolved phosphates increases very rapidly during the first few hours after moistening, then more slowly until germination occurs. Following germination, the amount of vacuolar phosphate continues to increase, while the cytoplasmic phosphate does not. These results are consistent with a mechanism in which K₂S₂O₈ inhibits growth by intercepting indoleacetic acid.