Quantification and biodegradability assessment of meso-2,3-dimercaptosuccinic acid adsorbed on iron oxide nanoparticles

Effects of dissolved organic matter on the environmental behavior and toxicity of metal nanomaterials: A review

Metal nanomaterials (MNMs) have been released into the environment during their usage in various products, and their environmental behaviors directly impact their toxicity. Numerous environmental factors potentially affect the behaviors and toxicity of MNMs with dissolved organic matter (DOM) playing the most essential role. Abundant facts showing contradictory results about the effects of DOM on MNMs, herein the occurrence of DOM on the environmental process change of MNMs such as dissolution, dispersion, aggregation, and surface transformation were summarized. We also reviewed the effects of MNMs on organisms and their mechanisms in the environment such as acute toxicity, oxidative stress, oxidative damage, growth inhibition, photosynthesis, reproductive toxicity, and malformation. The presence of DOM had the potential to reduce or enhance the toxicity of MNMs by altering the reactive oxygen species (ROS) generation, dissolution, stability, and electrostatic repulsion of MNMs. Furthermore, we summarized the factors that affected different toxicity including specific organisms, DOM concentration, DOM types, light conditions, detection time, and production methods of MNMs. However, the more detailed mechanism of interaction between DOM and MNMs needs further investigation.

Foliar application of the sulfhydryl compound 2,3-dimercaptosuccinic acid inhibits cadmium, lead, and arsenic accumulation in rice grains by promoting heavy metal immobilization in flag leaves

Mixed pollution due to heavy metals (HMs), especially cadmium (Cd), lead (Pb), and arsenic (As), seriously endangers the safety of food produced in paddy soil. In the field experiments, foliar application of 2,3-dimercaptosuccinic acid (DMSA) at the flowering stage was found to significantly reduce the levels of Cd, Pb, total As, and inorganic As (iAs) in rice grains by 47.95%, 61.76%, 36.37%, and 51.24%, respectively, without affecting the concentration of metallonutrients, including Mn, K, Mg, Ca, Fe, and Zn. DMSA treatment significantly reduced the concentrations of Cd, Pb, and As in the panicle node, panicle neck, and rachis, while those in the flag leaves were significantly increased by up to 20.87%, 49.40%, and 32.67%, respectively. DMSA application promoted the transport of HM from roots and lower stalks to flag leaves with a maximum increase of 34.55%, 52.65%, and 46.94%, respectively, whereas inhibited the transport of HM from flag leaves to panicle, rachis, and grains. Therefore, foliar application of DMSA reduced Cd, Pb, and As accumulation in rice grains by immobilizing HMs in flag leaves. Thus, this strategy could act as a promising agronomic measure for the remediation of mixed HM contamination in paddy fields.

Addressing the challenges to increase the efficiency of translating nanomedicine formulations to patients

INTRODUCTION

Nanotechnology is in a growth phase for drug delivery and medical imaging. Nanomaterials with unique properties present opportunities for encapsulation of therapeutics and imaging agents, along with conjugation to ligands for targeting. Favorable chemistry of nanomaterials can create formulations that address critical challenges for therapeutics, such as insolubility and a low capacity to cross the blood-brain-barrier (BBB) and intestinal wall.

AREAS COVERED

The authors investigate challenges faced during translation of nanomedicines while suggesting reasons as to why some nanoformulations have under-performed in clinical trials. They assess physiological barriers such as the BBB and gut mucus that nanomedicines must overcome to deliver cargos. They also provide an overview with examples of how nanomedicines can be designed to improve localization and site-specific delivery (e.g., encapsulation, bioconjugation, and triggered-release).

EXPERT OPINION

There are examples where nanomedicines have demonstrated improved efficacy of payload in humans; however, most of the advantages conferred were in improved pharmacokinetics and reduced toxicity. Problematic data show susceptibility of nanoformulations against natural protective mechanisms present in the body, including distribution impediment by physiological barriers and activation of the reticuloendothelial system. Further initiatives should address current challenges while expanding the scope of nanomedicine into advanced biomedical imaging and antibiotic delivery.

Molecular mechanism underlying the effects of temperature and pH on the size and surface charge of octenylsuccinated oat β-glucan aggregates

Environmental temperature and pH induced significant changes in the size and surface charge (ζ) of octenylsuccinated oat β-glucan aggregates. The underlying mechanisms were explored by using ¹H-NMR, fluorescence spectra, thermodynamic analysis, and SAXS. At pH 6.5, the size decreased with temperature while ζ continuously increased. With increasing pH at 293 K, parabolic and U-shaped trends were observed in the size and ζ, peaking at pH 8.5 and 6.5, respectively. At any tested pH, the size decreased with temperature. Overall, ζ significantly increased with temperature at each pH. As temperature increased, the compactness of hydrophobic-domains increased while the compactness of hydrophilic-domains decreased. In an acidic environment, both the compactness increased with decreasing pH, but in an alkaline environment, they decreased with pH. The compactness changes were co-driven by enthalpy and entropy and corresponded to changes in the hydrophobic interactions in hydrophobic-domains, hydrogen bonds in hydrophilic-domains and electrostatic repulsions among octenylsuccinate molecules.