Study on mechanism of removal of sudden Tetracycline by compound modified biological sand filtration process.

The removal of tetracycline from the sewage plant effluents through advanced treatment methods is key to controlling tetracycline levels in the water environment. In this study, modified quartz sands (QS) were used in a biological sand filter to remove tetracycline. The modified QS, with different surface characteristics, were prepared using glass etching technology combined with subsequent chemical modification methods, including hydroxylation treatment, metal ion modification, and amino modification. The adsorption efficiency of hydroxylated QS was higher than that of metal ion modified and amino modified QS, with adsorption efficiencies of 20.4331 mg/kg, 12.8736 mg/kg, and 10.1737 mg/kg, respectively. Results indicated that QS primarily reduce tetracycline through adsorption. Adsorption on ordinary QS fit the pseudo-first-order kinetic model, while adsorption on other modified QS and biofilm-coated QS fit the pseudo-second-order kinetics model. Biodegradation was identified as another mechanism for tetracycline reduction, which fit the zero-order kinetic model. Pseudomonas alcaligenes and unclassified Pseudomonas accounted for 96.6% of the total tetracycline-degrading bacteria. This study elucidates the effectiveness and mechanisms of five types of QS in treating tetracycline from sewage plant effluents. It provides a novel method for tetracycline reduction in real-world wastewater scenarios.

Nerve Defect Treatment with a Capping Hydroxyethyl Cellulose/Soy Protein Isolate Sponge Conduit for Painful Neuroma Prevention.

Painful neuroma, as one of the complications of nerve injury from disease or trauma, results in instinctive neuropathic pain that adversely affects a patient's quality of life. To intercept neuroma development, capping strategies have been performed as effective therapies. Nonetheless, the most appropriate biocompatible material to shield the nerves is an urgent clinical requirement. Herein, a compatible hydroxyethyl cellulose (HEC)/soy protein isolate (SPI) sponge capping conduit (HSSC) is used to prevent neuroma in vivo. Following capping on the sciatic nerve stump in vivo, the behavior of the rats and the structure of tissues are compared through histological assessment and autotomy scoring. The HSSCs gained a dismal autotomy score and enhanced the amelioration, where inflammatory invasions and overdeposition of collagen are defeated. The expression of myelin growth linked genes (Krox20, MPZ, and MAG) in the HSSC group at the eighth week was almost 2 times higher than that of the no capping group. The HSSC conduit served as a physical barrier to repress the infiltration of inflammation as well as provided an optimum microenvironment for facilitating nerve rejuvenation and intercepting neuroma development during nerve amelioration.

Injectable shape memory hydroxyethyl cellulose/soy protein isolate based composite sponge with antibacterial property for rapid noncompressible hemorrhage and prevention of wound infection.

Uncontrollable hemorrhage and subsequent wound infection are severe threats to life, especially for the deep noncompressible massive bleeding. However, traditional hemostatic materials are ineffective for extreme bleeding and subsequent wound infection. Here, we prepared an injectable shape memory hydroxyethyl cellulose/soy protein isolate based composite sponge (EHSS) for rapid noncompressible hemorrhage and prevention of wound infection. The nano silver (AgNPs)-loaded shape memory sponge (EHP@Ag) was fabricated by mussel-inspired polydopamine coating EHSS sponge, then reducing and immobilizing AgNPs in situ. The EHP@Ag sponges showed rapid blood-triggered shape recovery speed, which is beneficial for administering noncompressible hemorrhage. The results of the hemostatic experiment in vivo demonstrated that EHP@Ag sponge exhibited a desirable hemostasis effect (hemostasis time: 22.75 ± 3.86 s, blood loss: 285.25 ± 24.93 mg) compared to the commercial gelatin sponge (hemostasis time: 49.25 ± 3.30 s, blood loss: 755.50 ± 24.45 mg). Meanwhile, the EHP@Ag sponge has an efficient antibacterial property. Furthermore, the antibacterial experiment in vivo showed that the EHP@Ag sponges could kill bacteria effectively and reduce the bacteria-induced inflammatory response. In summary, the shape memory sponges can quickly control bleeding and avoid bacterial infection, which shows great potential for clinical application as a multifunctional hemostatic agent.

Biocompatible and antibacterial soy protein isolate/quaternized chitosan composite sponges for acute upper gastrointestinal hemostasis.

Innovative biomedical applications have high requirements for biomedical materials. Herein, a series of biocompatible, antibacterial and hemostatic sponges were successfully fabricated for the treatment of acute upper gastrointestinal bleeding (AUGB). Quaternized chitosan (QC) and soy protein isolate (SPI) were chemically cross-linked to obtain porous SPI/QC sponges (named SQS-n, with n = 30, 40, 50 or 60 corresponding to the weight percentage of the QC content). The chemical composition, physical properties and biological activity of SQS-n were investigated. SQS-n could support the adhesion and proliferation of L929 cells while triggering no obvious blood toxicity. Meanwhile, SQS-n exhibited good broad-spectrum antibacterial activity against both gram-positive bacteria (Staphylococcus aureus) and gram-negative bacteria (Escherichia coli). The in vivo hemostatic effect of SQS-n was evaluated using three different bleeding models. The results revealed that SQS-50 performed best in reducing blood loss and hemostatic time. The overall hemostatic effect of SQS-50 was comparable to that of a commercial gelatin sponge. The enhanced antibacterial and hemostatic activities of SQS-n were mainly attributed to the QC component. In conclusion, this work developed a QC-functionalized hemostatic sponge that is highly desirable for innovative biomedical applications, such as AUGB.

Combining 3D graphene-like screen-printed carbon electrode with methylene blue-loaded liposomal nanoprobes for phospholipase A2 detection.

Phospholipase A2 (PLA2) enzyme could be acted as a unique biomarker for forecasting and diagnosing certain diseases. Therefore, it is important to monitor PLA2 activity in biological and clinical samples. In this work, a simple electrochemical assay for PLA2 activity was developed based on a screen-printed carbon electrode (SPCE) with 3D graphene-like surface. When the PLA2-containing sample was mixed with the nanoprobes, i.e. the electroactive marker methylene blue (MB) encapsulated within nanometer-sized phospholipid liposomes, MB was released and adsorbed/enriched in site onto the surface of SPCE in a micro-cell. The encapsulation and enzymatic release of MB were evaluated using UV-Vis and fluorescence. The peak current due to oxidation of the adsorbed MB on the SPCE was measured by square-wave voltammetry (SWV). The current was directly linear to the PLA2 activity from 5 U/L to 200 U/L with a detection limit of 3 U/L. The same method can also be used for screening PLA2 inhibitors. Thus, the enrichment strategy developed in this work could be a promising signal amplification method for the sensitive and selective detection of PLA2 in biological or clinical samples.

Determination of mutated genes in the presence of wild-type DNA by using molecular beacons as probe.

Low-abundance mutations in the presence of wild-type DNA can be determined using molecular beacon (MB) as probe. A MB is generally used as DNA probe because it can distinguish single-base mismatched target DNA from fully matched target DNA. However, the probe can not determine low-abundance mutations in the presence of wild-type DNA. In this study, this limitation is addressed by enhancing the stability of unpaired base-containing dsDNA with a hydrogen-bonding ligand, which was added after hybridization of the MB to the target DNA. The ligand formed hydrogen bonds with unpaired bases and stabilized the unpaired base-containing dsDNA if target DNA is mutated one. As a result, more MBs were opened by the mutant genes in the presence of the ligand and a further increase in the fluorescence intensity was obtained. By contrast, fluorescence intensity did not change if target DNA is wild-type one. Consequent increase in the fluorescence intensity of the MB was regarded as a signal derived from mutant genes. The proposed method was applied in synthetic template systems to determine point mutation in DNA obtained from PCR analysis. The method also allows rapid and simple discrimination of a signal if it is originated in the presence of mutant gene or alternatively by a lower concentration of wild gene.

Signal-off impedimetric immunosensor for the detection of Escherichia coli O157:H7.

A signal-off impedimetric immune-biosensor based on gold nanoparticle (AuNP)-mediated electron transfer (ET) across a self-assembled monolayer (SAM) was the developed for highly sensitive detection of Escherichia coli O157:H7 bacteria. The biosensor was fabricated by covalently grafting an anti-Escherichia coli O157:H7 antibody onto SAM-modified gold electrodes. Following bacterial capture, the sensor was further modified by the gold nanoparticles (AuNPs). Due to the strong interaction between AuNPs and Escherichia coli O157:H7, AuNPs attached to the surface of the bacteria and acted as ET pathways across the insulating SAMs on the electrode surface, resulting in a significant reduction of the electron transfer resistance (Ret) between the [Fe(CN)6](3-/4-) redox probe in the solution and the substrate gold surface. Therefore, the attachment AuNPs to captured bacteria significantly enhanced the sensitivity for Escherichia coli O157:H7 bacteria detection.

Quantum dot cluster (QDC)-loaded phospholipid micelles as a FRET probe for phospholipase A2 detection.

A simple assay for phospholipase A2 (PLA2) enzyme was developed based on a fluorescence resonance energy transfer (FRET) probe using the quantum dot cluster (QDC)-loaded phospholipid micelles. The probe was prepared by encapsulating many small hydrophobic quantum dots (QDs) within the hydrophobic core of micelles that were formed from the coassembly of hydrogenated soy phosphatidylcholine phospholipids (HSPC) and fluorescent lipids (NBD-PC). QDCs formed within the micelle core served as the substrate for NBD fluorescence quenching through FRET. The QDC-loaded micelles showed very low background fluorescence. As the PLA2 enzyme selectively digested lipids, the NBD fluorescence was recovered from its quenched state, leading to the sensitive detection of PLA2. This assay provided a limit of detection (at a signal-to-noise ratio of 3) of 3 U/L for PLA2. In the presence of a PLA2 inhibitor, the fluorescent response of the sensor for PLA2 decreased, indicating that the assay could also be used for screening the PLA2 inhibitors.