The Widespread Use of Nanomaterials: The Effects on the Function and Diversity of Environmental Microbial Communities.

In recent years, as an emerging material, nanomaterials have rapidly expanded from laboratories to large-scale industrial productions. Along with people's productive activities, these nanomaterials can enter the natural environment of soil, water and atmosphere through various ways. At present, a large number of reports have proved that nanomaterials have certain toxic effects on bacteria, algae, plants, invertebrates, mammalian cell lines and mammals in these environments, but people still know little about the ecotoxicology of nanomaterials. Most relevant studies focus on the responses of model strains to nanomaterials in pure culture conditions, but these results do not fully represent the response of microbial communities to nanomaterials in natural environments. Over the years, the effect of nanomaterials infiltrated into the natural environment on the microbial communities has become a popular topic in the field of nano-ecological environment research. It was found that under different environmental conditions, nanomaterials have various effects on the microbial communities. The medium; the coexisting pollutants in the environment and the structure, particle size and surface modification of nanomaterials may cause changes in the structure and function of microbial communities. This paper systematically summarizes the impacts of different nanomaterials on microbial communities in various environments, which can provide a reference for us to evaluate the impacts of nanomaterials released into the environment on the microecology and has certain guiding significance for strengthening the emission control of nanomaterials pollutants.

Magnetic Molecularly Imprinted Polymers: Synthesis and Applications in the Selective Extraction of Antibiotics.

Recently, magnetic molecularly imprinted polymers (MMIPs) have integrated molecular imprinting technology (MIT) and magnetic separation technology and become a novel material with specific recognition and effective separation of target molecules. Based on their special function, they can be widely used to detect contaminants such as antibiotics. The antibiotic residues in the environment not only cause harm to the balance of the ecosystem but also induce bacterial resistance to specific antibiotics. Given the above consideration, it is especially important to develop sensitive and selective methods for measuring antibiotics in the complex matrix. The combination of MMIPs and conventional analytical methods provides a rapid approach to separate and determine antibiotics residues. This article gives a systematic overview of synthetic approaches of the novel MMIPs materials, briefly introduces their use in sample pretreatment prior to antibiotic detection, and provides a perspective for future research.

Physiological and transcriptomic analyses reveal mechanistic insight into the adaption of marine Bacillus subtilis C01 to alumina nanoparticles.

An increasing number of studies have investigated the effects of nanoparticles (NPs) on microbial systems; however, few existing reports have focused on the defense mechanisms of bacteria against NPs. Whether secondary metabolism biosynthesis is a response to NP stress and contributes to the adaption of bacteria to NPs is unclear. Here, a significant induction in the surfactin production and biofilm formation were detected by adding Al2O3 NPs to the B. subtilis fermentation broth. Physiological analysis showed that Al2O3 NP stress could also affect the cell and colony morphogenesis and inhibit the motility and sporulation. Exogenously adding commercial surfactin restored the swarming motility. Additionally, a suite of toxicity assays analyzing membrane damage, cellular ROS generation, electron transport activity and membrane potential was used to determine the molecular mechanisms of toxicity of Al2O3 NPs. Furthermore, whole transcriptomic analysis was used to elucidate the mechanisms of B. subtilis adaption to Al2O3 NPs. These results revealed several mechanisms by which marine B. subtilis C01 adapt to Al2O3 NPs. Additionally, this study broadens the applications of nanomaterials and describes the important effects on secondary metabolism and multicellularity regulation by using Al2O3 NPs or other nano-products.

Label-Free Electrochemiluminescence Aptasensor for 2,4,6-Trinitrotoluene Based on Bilayer Structure of Luminescence Functionalized Graphene Hybrids.

The electrochemiluminescence (ECL) behavior of N-(aminobutyl)-N-(ethylisoluminol)/hemin dual-functionalized graphene hybrids (A-H-GNs) and luminol-functionalized silver/graphene oxide composite (luminol-AgNPs-GO) was investigated under cyclic voltammetry and pulse potential. It was found that A-H-GNs and luminol-AgNPs-GO exhibited excellent ECL activity. On this basis, a label-free ECL aptasensor for 2,4,6-trinitrotoluene (TNT) detection was developed based on bilayer structure of luminescence functionalized graphene hybrids consisting of A-H-GNs and luminol-AgNPs-GO. First, positively charged chitosan-coated A-H-GNs were modified on the surface of indium-doped tin oxide electrode by simple dripping and drying in the air; after that, the modified electrode was immersed in negatively charged luminol-AgNPs-GO modified with aptamer (apta-biotin-SA-luminol-AgNPs-GO) to form apta-biotin-SA-luminol-AgNPs-GO/CS-A-H-GNs/ITO electrode (i.e., aptasensor) by electrostatic interaction. In the presence of TNT, a remarkable decrease in ECL signals was observed due to the formation of aptamer-TNT complex. TNT could be detected based on the inhibition effect. The aptasensor exhibits a wide dynamic range from 1.0 × 10(-12) to 1.0 × 10(-9) g/mL, with a low detection limit of 6.3 × 10(-13) g/mL for the determination of TNT, which is superior to most previously reported bioassays for TNT. Moreover, the proposed aptasensor has been successfully applied to the detection of TNT in environmental water. It is sensitive, selective, and simple, avoiding complicated labeling and purification procedures. Due to the wide target recognition range of aptamer, this strategy provides a promising way to develop new aptasensor for other analytes.

A competitive immunoassay for sensitive detection of small molecules chloramphenicol based on luminol functionalized silver nanoprobe.

Chloramphenicol (CHL) as a broad-spectrum antibiotic has a broad action spectrum against Gram-positive and Gram-negative bacteria, as well as anaerobes. The use of CHL is strictly restricted in poultry because of its toxic effect. However, CHL is still illegally used in animal farming because of its accessibility and low cost. Therefore, sensitive methods are highly desired for the determination of CHL in foodstuffs. The immunoassays based on labeling as an important tool have been reported for the detection of CHL residues in food-producing animals. However, most of the labeling procedures require multi-step reactions and purifications and thus they are complicated and time-consuming. Recently, in our previous work, luminol functionalized silver nanoparticles have been successfully synthesized, which exhibits higher CL efficiency than luminol functionalized gold nanoparticles. In this work, the new luminol functionalized silver nanoparticles have been used for the labeling of small molecules CHL for the first time and a competitive chemiluminescent immunoassay has been developed for the detection of CHL. Owing to the amplification of silver nanoparticles, high sensitivity for CHL could be achieved with a low detection limit of 7.6×10(-9) g mL(-1) and a wide linear dynamic range of 1.0×10(-8)-1.0×10(-6) g mL(-1). This method has also been successfully applied to determine CHL in milk and honey samples with a good recoveries (92% and 102%, 99% and 107% respectively), indicating that the method is feasible for the determination of CHL in real milk and honey samples. The labeling procedure is simple, convenient and fast, superior to previously reported labeling procedures. The immunoassay is also simple, fast, sensitive and selective. It is of application potential for the determination of CHL in foodstuffs.

A homogeneous hemin/G-quadruplex DNAzyme based turn-on chemiluminescence aptasensor for interferon-gamma detection via in-situ assembly of luminol functionalized gold nanoparticles, deoxyribonucleic acid, interferon-gamma and hemin.

A homogeneous hemin/G-quadruplex DNAzyme (HGDNAzyme) based turn-on chemiluminescence aptasensor for interferon-gamma (IFN-γ) detection is developed, via dynamic in-situ assembly of luminol functionalized gold nanoparticles (lum-AuNPs), DNA, IFN-γ and hemin. The G-quadruplex oligomer of the HGDNAzyme was split into two halves, which was connected with the complementary sequence of P1 (IFN-γ-binding aptamer) to form the oligonucleotide P2. P2 hybridized with IFN-γ-binding aptamer and meanwhile assembled onto lum-AuNPs through biotin-streptavidin specific interaction. When IFN-γ was recognized by aptamer, P2 was released into the solution. The two lateral portions of P2 combined with hemin to yield the catalytic hemin/G-quadruplex DNAzyme, which amplified the luminol oxidation for a turn-on chemiluminescence signaling. Based on this strategy, the homogeneous aptasensor enables the facile detection of IFN-γ in a range of 0.5-100 nM. Moreover, the aptasensor showed high sensitivity (0.4 nM) and satisfactory specificity, pointing to great potential applications in clinical analysis.