Phosphate Groups Research Articles

Fabrication of highly conductive VXC-72R carbon nanoparticles decorated Zr (IV)-based metal-organic framework for highly sensitive detection of methyl parathion

A simple and efficient ultrasonic-assisted strategy was used to prepare the nanocomposite of Vulcan XC-72R carbon (VXC-72R) nanoparticles and Zr(IV)-based metal-organic framework (UIO-66) nanoparticles. For the multifunctional VXC-72R@UIO-66 nanocomposite, VXC-72R nanoparticles possessed good conductivity property and good dispersion, which were conductive to form the interconnected carbon conductive channels; UIO-66 nanoparticles could improve the accumulation ability of methyl parathion (MP) because of the high affinity of Zr-O groups with phosphoric groups. Moreover, the introduction of VXC-72R nanoparticles could effectively make up the conductivity property of UIO-66 nanoparticles. The VXC-72R@UIO-66/GCE sensor presented good MP detection performance with limit of detection (LOD) of 1.35 nM (Linear MP concentration range: 0.01–10 μM). When used for the detection of MP in juice samples, the VXC-72R@UIO-66/GCE sensor showed acceptable recoveries of 96.00–104.67 %.

A novel electrochemiluminescence aptasensor for ultrasensitive lincomycin detection using Ti3C2–TiO2–Ru probe

The presence of lincomycin (LIN) residues in food poses significant health risks to humans, necessitating a highly sensitive and specific detection method for LIN. This study used a self-enhancing Ti3C2–TiO2–Ru probe to develop an electrochemiluminescence aptasensor to detect LIN. The Ti3C2–TiO2 was synthesized in situ by harnessing the unique reducibility of Ti3C2, with TiO2 serving as a co-reaction accelerator. Moreover, Ti3C2–TiO2 served as a carrier with an excellent negative charge, allowing for the immobilization of a substantial amount of Ru(bpy)32+ through electrostatic adsorption, thus forming a self-enhancing Ti3C2–TiO2–Ru probe. Furthermore, the specific affinity of LIN toward the aptamer and the chelating interaction between the Ti and phosphate groups ensured highly precise LIN detection. This sensor demonstrated excellent performance, with a detection limit of 0.025 ng mL−1 and a detection range of 1.0 × 10−1–1.0 × 104 ng mL−1. The LIN detection in milk showed commendable recovery rates, ranging from 94.4% to 106.0%.

Responses of Dunaliella sp. AL-1 to chromium and copper: Biochemical and physiological studies

Microalgae have gained recognition as versatile candidates for the remediation of heavy metals (HMs). This study investigated the biosorption potential of Dunaliella sp. AL1 for copper (Cu(II)) and hexavalent chromium (Cr(VI)) in aqueous solutions. The marine microalga Dunaliella sp. AL1 was exposed to half-sublethal concentrations of both metals in single and bimetallic systems, and responses in algal growth, oxidative stress, photosynthetic pigment production, and photosynthetic performance were evaluated. Cu and/or Cr exposure increased the generation of reactive oxygen species (ROS) in microalgae cells but did not impact algal growth. In terms of photosynthesis, there was a decrease in chlorophylls and carotenoids production in the microalgae culture treated with Cr, either alone or in combination with Cu. The study recorded promising metal removal efficiencies: 26.67%–20.11% for Cu and 94.99%–95.51% for Cr, in single and bimetallic systems, respectively. FTIR analysis revealed an affinity of Cu and Cr ions towards aliphatic/aldehyde C–H, N–H bending, and phosphate groups, suggesting the formation of complex bonds. Biochemical analysis of microalgae biomass collected after the removal of Cr alone or in combination with Cu showed a significant decrease in total carbohydrate content and soluble protein levels. Meanwhile, higher lipid accumulation was recorded and evidenced by BODIPY 505/515 staining. Fatty acid composition analysis by GC revealed a modulation in lipid composition, with a decrease in the ratio of unsaturated fatty acids (UFA) to saturated fatty acids (SFA), in response to Cu, Cr, and Cu–Cr exposure, indicating the suitability of the biomass for sustainable biofuel production.

NucleoFind: a deep-learning network for interpreting nucleic acid electron density.

Nucleic acid electron density interpretation after phasing by molecular replacement or other methods remains a difficult problem for computer programs to deal with. Programs tend to rely on time-consuming and computationally exhaustive searches to recognise characteristic features. We present NucleoFind, a deep-learning-based approach to interpreting and segmenting electron density. Using an electron density map from X-ray crystallography obtained after molecular replacement, the positions of the phosphate group, sugar ring and nitrogenous base group can be predicted with high accuracy. On average, 78% of phosphate atoms, 85% of sugar atoms and 83% of base atoms are positioned in predicted density after giving NucleoFind maps produced following successful molecular replacement. NucleoFind can use the wealth of context these predicted maps provide to build more accurate and complete nucleic acid models automatically.

Programmable Framework Nucleic Acid-Modified Nanomagnetic Beads for Efficient Isolation of Exosomes and Exosomal Proteomics Analysis.

Exosomes are increasingly being regarded as emerging and promising biomarkers for cancer screening, diagnosis, and therapy. The downstream molecular analyses of exosomes were greatly affected by the isolation efficiency from biosamples. Among the current exosome isolation strategies, affinity nanomaterials performed comparably better with selectivity and specificity. However, these techniques did not take the structure and size of exosomes into account, which may lead to a loss of isolation efficiency. In this article, a framework nucleic acid was employed to prepare a well-designed nanosized bead Fe3O4@pGMA@DNA TET@Ti4+ for enrichment of exosomes. The abundant phosphate groups in the framework nucleic acid provide binding sites to immobilize Ti4+, and its rigid three-dimensional skeleton makes them act as roadblocks to barricade exosomes and provide affinity interactions on a three-dimensional scale, resulting in the improvement of isolation efficiency. The model exosomes can be effectively isolated with 92% recovery in 5 min. From 100 μL of HeLa cell culture supernatant, 34 proteins out of the top 100 commonly identified exosomal proteins were identified from the isolated exosomes by the novel beads, which is obviously more than that by TiO2 (19 proteins), indicating higher isolation efficiency and exosome purity by Fe3O4@pGMA@DNA TET@Ti4+ beads. The nanobeads were finally applied for comparing exosomal proteomics analysis from real clinical serum samples. Twenty-five upregulated and 10 downregulated proteins were identified in the lung cancer patients group compared to the health donors group, indicating that the novel nanobeads have great potential in isolation of exosomes for exosomal proteomics analysis in cancer screening and diagnosis.

Benzohydroxamate and nitrobenzohydroxamate affect membrane order: Correlations between spectroscopic and molecular dynamics to approach tuberculosis

This work correlates the effects of benzohydroxamate (BH) and nitrobenzohydroxamate (NBH) anions in two membrane models which may be used for anti-tuberculosis (anti-TB) spectroscopic studies and/or computational studies. Firstly, the BH and NBH influence in the physico-chemical properties of soy asolectin (ASO)-based large multilamellar vesicles (MLVs) were evaluated by spectroscopic and calorimetric studies. In parallel, the BH and NBH interaction with a Mycobacterium tuberculosis (Mtb) inner membrane model, composed of phosphatidyl-myo-inositol-dimannoside (PIM2), was investigated by molecular dynamics (MD) simulations. Spectroscopic data showed a localization of BH close to the lipid phosphate group, while NBH was found close to the choline region. The BH ordered the ASO choline, phosphate and carbonyl regions and disrupted the acyl methylenes, reducing the membrane packing of the lipid hydrophobic region. On the other hand, NBH showed an ordering effect in all the lipid groups (polar, interface and hydrophobic ones). By MD studies, it was found that NBH enhanced the stability of the PIM2 membrane more than BH, while also being positioned closer to its mannosyl oxygens. As in ASO MLVs, BH was localized close to the PIM2 phosphate group and disrupted its acyl chains. However, higher values of lateral diffusion were observed for NBH than BH. Despite this, BH and NBH increased the membrane thickness by 35 %, which suggests a global ordering effect of both drugs. Findings of this work reinforce the accordance and complementarity between MLVs based on ASO and the PIM2 MD model results to study the drug effects in Mtb membrane properties.

Assembly of protein-directed fluorescent gold nanoclusters for high-sensitivity detection of uranyl ions

Uranium is a key element in the nuclear industry, whose accidental release causes health and environmental problems. In this paper, a protein-directed fluorescent sensor with aggregation-induced emission characteristics (gold nanoclusters@ovalbumin, AuNCs@OVA) was synthesized for the detection of UO22+ with high sensitivity and selectivity. The sensor exhibited good fluorescence stability, and its fluorescence intensity could be selectively enhanced by UO22+. Based on FT-IR and XPS analyses, the increase in fluorescence intensity of AuNCs@OVA after the addition of UO22+ was attributed to aggregation induced by the complexation between UO22+ and the amino, carboxyl, hydroxyl, and phosphate groups of ovalbumin. The detection limit was determined to be 34.4 nM, and the sensor showed excellent ion selectivity for UO22+. In combination with a smartphone program, the sensor could realize the real-time detection of UO22+ in a quantitative and portable way.

Phosphoryl group wires stabilize pathological tau fibrils as revealed by multiple quantum spin counting NMR.

Hyperphosphorylation of the protein tau is one of the biomarkers of neurodegenerative diseases in the category of tauopathies. However, the molecular level, mechanistic, role of this common post-translational modification (PTM) in enhancing or reducing the aggregation propensity of tau is unclear, especially considering that combinatorial phosphorylation of multiple sites can have complex, non-additive, effects on tau protein aggregation. Since tau proteins stack in register and parallel to elongate into pathological fibrils, phosphoryl groups from adjacent tau strands with 4.8 Å separation must find an energetically favorable spatial arrangement. At first glance, this appears to be an unfavorable configuration due to the proximity of negative charges between phosphate groups from adjacent neighboring tau fibrils. However, this study tests a counterhypothesis that phosphoryl groups within the fibril core-forming segments favorably assemble into highly ordered, hydrogen-bonded, one-dimensionally extended wires under biologically relevant conditions. We selected two phosphorylation sites associated with neurodegeneration, serine 305 (S305p) and tyrosine 310 (Y310p), on a model tau peptide jR2R3-P301L (tau295-313) spanning the R2/R3 splice junction of tau, that readily aggregate into a fibril with characteristics of a seed-competent mini prion. Using multiple quantum spin counting (MQ-SC) by 31P solid-state NMR of phosphorylated jR2R3-P301L tau peptide fibrils, enhanced by dynamic nuclear polarization, we find that at least six phosphorous spins must neatly arrange in 1D within fibrils or in 2D within a protofibril to yield the experimentally observed MQ-coherence orders of four. We found that S305p stabilizes the tau fibrils and leads to more seeding-competent fibrils compared to jR2R3 P301L or Y310p. This study introduces a new concept that phosphorylation of residues within a core forming tau segment can mechanically facilitate fibril registry and stability due a hitherto unrecognized role of phosphoryl groups to form highly ordered, extended, 1D wires that stabilize pathological tau fibrils.

A Multimodal System for Lipid A Structural Analysis from a Single Colony.

Structural elucidation of Gram-negative bacterial lipid A traditionally requires chemical extraction followed by tandem MS data in the negative ion mode. Previously, we reported FLAT and FLATn as methods to rapidly determine the structure of lipid A without chromatographic techniques. In this work, we extend the capability and effectiveness of these techniques to elucidate the chemical structure in a de novo manner by including the use of positive ion mode (FLAT+ and FLATn+) spectral approaches. Advantages of positive mode analysis of lipid A include the generation of more interpretable and informative fragmentation patterns that include the identification of diagnostic fragments, including selective dissociation of a glycosidic bond between two glucosamine units and the selective dissociation at the secondary acyl chain in 2'-N, allowing for the determination of the composition of fatty acids. As a proof of principle, we present here two previously uncharacterized structures of lipid A from Roseomonas mucosa (R. mucosa) and Moraxella canis (M. canis). In R. mucosa, we determined the lipid A structure with a nonconventional backbone of-β-1,6 linked 2,3-dideoxy-2,3-diamno-d-glucopyranose further modified with galacturonic acid in the place of typical 1-phosphate, and in M. canis, we assigned a single discrete structure using the specific fragmentation patterns of terminal phosphate groups present in lipid A. Therefore, FLATn+, in combination with FLAT and FLATn, provides a multimodal structural platform for rapid structure characterization of unusual and complex lipid A structures from a single colony.

Kinetic Properties of Combustion and Pyrolysis of Masson Pine with Synergistic Flame Retardancy by GUP-APP-silica Sol

ABSTRACT In order to investigate the effect of guanylurea phosphate-ammonium polyphosphate-silica sol on the combustion and pyrolysis characteristics of Masson Pine, UL-94 horizontal and vertical burner, LOI tester, cone calorimeter, and thermogravimetric analysis were used to study the flame retardant wood, and Coats-Redfern model was used to analyze its pyrolysis kinetics. The results showed that the combined use of guanylurea phosphate-ammonium polyphosphate-silica sol had a significant synergic flame retardant effect on Masson pine. When the mass ratio of guanylurea phosphate, ammonium polyphosphate, and silica sol was 2:1:1, the heat release rate and total heat release of flame retardant pine were decreased by 54.7% and 44.7% compared with pure Masson pine, and the LOI was increased by 77.8% compared with the control group. In addition, the addition of silica sol in the flame retardant reduces the effect of flame retardant on the mechanical properties of wood. Raman analysis of carbon layer showed that the R-value of char residue decreased by 5% and 13% when the mass fraction ratio of guanylurea phosphate, ammonium polyphosphate, and silica sol was 5:1:2 and 2:1:1, respectively, indicating that the compound flame retardant effectively promoted the conversion of amorphous carbon into graphite structure. The TG results of the 5:1:2 and 2:1:1 ratios of guanylurea phosphate, ammonium polyphosphate, and silica sol groups showed that the pyrolysis temperature of flame-retardant pine advanced by about 100°C at the heating rate of 15 ℃/min, and the final char residue rate and apparent activation energy were 15.22%, 18.61%, 24.35 kJ/mol, and 23.76 kJ/mol, respectively. These results indicated that the synergistic flame retardant system of guanylurea phosphate-ammonium polyphosphate-silica sol reduced the apparent activation energy of pine pyrolysis, effectively inhibited the pyrolysis of Masson Pine, and enhanced the thermal stability, char forming ability, and flame retardant property.

Effect of Terminal Phosphate Groups on Collisional Dissociation of RNA Oligonucleotide Anions.

The increasing need for mass spectrometric analysis of RNA molecules calls for a better understanding of their gas-phase fragmentation behaviors. In this study, we investigate the effect of terminal phosphate groups on the fragmentation spectra of RNA oligonucleotides (oligos) using high-resolution mass spectrometry (MS). Negative-ion mode collision-induced dissociation (CID) and higher-energy collisional dissociation (HCD) were carried out on RNA oligos containing a terminal phosphate group on either end, both ends, or neither end. We find that terminal phosphate groups affect the fragmentation behavior of RNA oligos in a way that is dependent on the precursor charge state and the oligo length. Specifically, for precursor ions of RNA oligos of the same sequence, those with 5'- or 3'-phosphate, or both, have a higher charge state distribution and lose the phosphate group(s) in the form of a neutral (H3PO4 or HPO3) or an anion ([H2PO4]- or [PO3]-) upon CID or HCD. Such a neutral or charged loss is most conspicuous for precursor ions of an intermediate charge state, e.g., 3- for 4-nt oligos or 4- and 5- for 8-nt oligos. This decreases the intensity of sequencing ions (a-, a-B, b-, c-, d-, w-, x-, y-, z-ions) and hence is unfavorable for sequencing by CID or HCD. Removal of terminal phosphate groups by calf intestinal alkaline phosphatase improved MS analysis of RNA oligos. Additionally, the intensity of a fragment ion at m/z 158.925, which we identified as a dehydrated pyrophosphate anion ([HP2O6]-), is markedly increased by the presence of a terminal phosphate group. These findings expand the knowledge base necessary for software development for MS analysis of RNA.

Effect of phytic acid/rust conversion layer on corrosion protection of rusty mild steel

In this study, a rust/phytic acid (rust/PA) conversion layer was prepared on rusty mild steel by dipping rusty steel panels into a phytic acid solution. After treating with phytic acid, the free phosphate group in the conversion layer chelated with Fe3+ and generated insoluble salt, which could form a new dense conversion layer. The dense rust/PA conversion layer effectively strengthened the interfacial bonding between the coatings and rusty metal substrate and exhibited good corrosion protection and defect healing abilities.

A Small-Molecule NIR-II Probe for the Diagnosis of Hemorrhagic Diseases.

Numerous hemorrhagic disorders, particularly those presenting deep hemorrhage, pose diagnostic challenges, often leading to delayed treatment and severe outcomes. Near-infrared (NIR)-II fluorescence imaging offers advantages such as deep tissue penetration, real-time visualization, and a high signal-to-background ratio, making it highly suitable for diagnosing hemorrhagic diseases. In this study, an NIR-II fluorescent probe LJ-2P carrying carboxylic and phosphoric acid groups is successfully applied for imaging hemorrhagic diseases. LJ-2P demonstrates a strong affinity for fibrinogen and fibrin clots both computationally and experimentally, thus exhibiting increased brightness upon coagulation. As compared to Indocyanine Green, LJ-2P provides a longer imaging window, higher imaging specificity, and signal-to-background ratio, as well as superior photobleaching resistance in three disease models: gastric, pulmonary, and cerebral hemorrhages. These results reveal that LJ-2P demonstrates enhanced imaging capabilities, enabling precise identification of hemorrhagic sites.

The lipopolysaccharide structure affects the detoxifying ability of intestinal alkaline phosphatases

Lipopolysaccharide (LPS) is one of the most potent mediators of inflammation. In swine husbandry, weaning is associated with LPS-induced intestinal inflammation, resulting in decreased growth rates due to malabsorption of nutrients by the inflamed gut. A potential strategy to treat LPS-mediated disease is administering intestinal alkaline phosphatase (IAP). The latter can detoxify lipid A, the toxic component of LPS, by removal of phosphate groups. Currently, 183 LPS O-serotypes from E. coli have been described, however, comparative experiments to elucidate functional differences between LPS serotypes are scarce. In addition, these functional differences might affect the efficacy of LPS detoxifying enzymes. Here, we evaluated the ability of four LPS serotypes (O26:B6, O55:B5, O111:B4 and O127:B8) derived from Escherichia coli to trigger the secretion of pro-inflammatory cytokines by porcine PBMCs. We also tested the ability of three commercially available IAPs to detoxify these LPS serotypes. The results show that LPS serotypes differ in their ability to trigger cytokine secretion by immune cells, especially at lower concentrations. Moreover, IAPs displayed a different detoxification efficiency of the tested serotypes. Together, this study sheds light on the impact of LPS structure on the detoxification by IAPs. Further research is however needed to elucidate the LPS serotype-specific effects and their implications for the development of novel treatment options to alleviate LPS-induced gut inflammation in weaned piglets.

Phytic Acid Modification Enhanced Cadmium Sorption and Immobilization of Sludge-based Hydrochar

Phytic acid-assisted sludge hydrothermal carbonization was employed to synthesize phytic acid-modified hydrochar via a one-step method. The surface morphology, pore structure, elemental composition, functional groups, and thermal stability of the phytic acid-modified hydrochar were characterized. Sorption kinetics and isotherm experiments were conducted to investigate the effects of humic acid, temperature, and pH on the sorption process of cadmium （Cd） onto the phytic acid-modified hydrochar. The Cd fixation ability was evaluated through soil passivation experiments. The results demonstrated that the surface of the phytic acid-modified hydrochar exhibited an abundance of phosphoric acid groups, enhanced electronegativity, and thermal stability. Furthermore, both the sorption rate and maximum sorption capacity for Cd increased by 1.88 times and 1.22 times compared to that in unmodified hydrochar, respectively, owing to the presence of phosphoric acid groups that enhanced complexation and electrostatic interaction with Cd. Elevated temperatures, higher pH values, and coexistence with humic acids were beneficial for enhancing Cd sorption onto phytic acid-modified hydrochar. When heavy metals such as Cu, Zn, and Pb coexisted, the sorption capacity of phytic acid-modified hydrochar for Cd was 0.77-6.88 times higher than that for other metals. Phyic acid-modified hydrochar exhibited excellent efficiency in fixing Cd （56.1%-81.l%）, mitigating the loss of available nutrients in soil and significantly increasing the AP content in the soil. In conclusion, the use of phytic acid-modified hydrochar could effectively remove Cd from water and serve as a promising soil amendment for stabilizing soil Cd content.

Molecular Mechanism of Double-Displacement Retaining β-Kdo Glycosyltransferase WbbB.

Glycosyltransferases (GTs) are pivotal enzymes involved in glycosidic bond synthesis, which can lead to either retention or inversion of the glycosyl moiety's anomeric configuration. However, the catalytic mechanism for retaining GTs remains a subject of controversy. In this study, we employ MD and QM/MM metadynamics to investigate the double-displacement catalytic mechanism of the retaining β-Kdo transferase WbbB. Our findings demonstrate that the nucleophile Asp232 initiates the reaction by attacking the sugar ring containing a carboxylate at the anomeric position, forming a covalent adduct. Subsequently, the adduct undergoes a rotational rearrangement, ensuring proper orientation of the anomeric carbon for the acceptor substrate. In the second step, Glu158 acts as the catalytic base to abstract the proton of the acceptor substrate to complete the transglycosylation reaction. Notably, His265 does not function as the anticipated catalytic acid; instead, it stabilizes the phosphate group through H-bonding interactions. Our simulations support the double-displacement mechanism implicated from the crystallographic studies of WbbB. This mechanism deviates from the common SNi-type and retaining glycoside hydrolase mechanisms, thereby expanding our understanding of GT catalytic mechanisms.

Effects of Carbon-Based Modified Materials on Soil Water and Fertilizer Retention and Pollution Control in Rice Root Zone

To seek an appropriate stabilization and remediation scheme for cadmium (Cd) and arsenic (As) pollution in farmland, a typical polluted soil sample was selected from a mining area in Southwest China for a soil box simulation experiment. Biochar (BC), a modified type of biochar made from rice husk with different mass ratios of ferric chloride and rice husk, was set up (the mass ratio of ferric chloride to rice husk was 1:9 (defined as LFB), 3:7 (defined as MFB), and 5:5 (defined as HFB) and the control group (BL)) to explore the effects of soil water and fertilizer loss, the bioavailability of Cd and As, and the bioenrichment effects of plant organs during the growth period of rice. The results showed that the porous structure and large specific surface area of biochar effectively regulated soil aggregate composition and improved soil water holding capacity. Compared to the BL treatment, soil water storage under the four carbon-based material control modes increased from 8.98% to 14.52%. Biochar has a strong ion exchangeability and can absorb soil ammonium, nitrogen, and phosphoric acid groups, effectively inhibiting the loss of soil fertilizer. Biochar improves soil pH and reduces the specific gravity of exchangeable Cd. In addition, the oxygen-containing functional groups in biochar can react with metals in a complex manner. The diethylenetriaminepentaacetic acid (DTPA) concentrations of Cd in soils treated with BC, LFB, MFB, and HFB were 79.69%, 72.92%, 64.58%, and 69.27% lower, respectively, than those treated with BL. In contrast, the Fe3+ in ferric chloride combines with As after hydrolysis and oxidation to form amorphous ferric arsenate precipitates or insoluble secondary minerals. Therefore, the curing effect of the modified biochar on As was more potent than that of applied biochar alone. In conclusion, ferric chloride-modified biochar can effectively inhibit the effects of water and fertilizer loss in farmland soil and realize cross-medium long-term inhibition and control of combined Cd and As pollution.

Reconfigurable Optical Sensor for Metal-Ion-Mediated Label-Free Recognition of Different Biomolecular Targets.

Reconfiguration of chemical sensors, intended as the capacity of the sensor to adapt to novel operational scenarios, e.g., new target analytes, is potentially game changing and would enable rapid and cost-effective reaction to dynamic changes occurring at healthcare, environmental, and industrial levels. Yet, it is still a challenge, and rare examples of sensor reconfiguration have been reported to date. Here, we report on a reconfigurable label-free optical sensor leveraging the versatile immobilization of metal ions through a chelating agent on a nanostructured porous silica (PSiO2) optical transducer for the detection of different biomolecules. First, we show the reversible grafting of different metal ions on the PSiO2 surface, namely, Ni2+, Cu2+, Zn2+, and Fe3+, which can mediate the interaction with different biomolecules and be switched under mild conditions. Then, we demonstrate reconfiguration of the sensor at two levels: 1) switching of the metal ions on the PSiO2 surface from Cu2+ to Zn2+ and testing the ability of Cu2+-functionalized and Zn2+-reconfigured devices for the sensing of the dipeptide carnosine (CAR), leveraging the well-known chelating ability of CAR toward divalent metal ions; and 2) reconfiguration of the Cu2+-functionalized PSiO2 sensor for a different target analyte, namely, the nucleotide adenosine triphosphate (ATP), switching Cu2+ with Fe3+ ions to exploit the interaction with ATP through phosphate groups. The Cu2+-functionalized and Zn2+-reconfigured sensors show effective sensing performance in CAR detection, also evaluated in tissue samples from murine brain, and so does the Fe3+-reconfigured sensor toward ATP, thus demonstrating effective reconfiguration of the sensor with the proposed surface chemistry.

In-situ polymerization of phosphorus/nitrogen flame-retardant coating for polyester/cotton blend fabrics with superior durability

The durable flame-retardant functional coating of polyester/cotton (T/C) blend fabrics is both interesting and challenging. In this study, a novel in-situ polymerization strategy for phosphorus/nitrogen-based flame-retardant on T/C blend samples was developed through the polycondensation of tetramethylolphosphonium sulfate, dicyandiamide, and anionic cyclic phosphate ester. The chemical structure of the polycondensation compounds, as well as the surface morphology, combustion behavior, flame-retardant capacity, washing durability and flame-retardant mechanism of the coated T/C blend fabrics, were investigated. The coated T/C blend fabrics demonstrated excellent self-extinguishing performance, with the damaged length decreasing to as low as 8.0 cm and the LOI reaching 28 %. Moreover, the peak heat release rate of the coated T/C blend fabrics decreased by 39.7 %. The superior flame retardancy can be attributed to the enhanced dehydration and carbonization by phosphate groups in the condensed phase, as well as the quenching effect and diluting effect in the gas phase. Additionally, the coated T/C blend fabrics exhibited remarkable washing durability and still achieved self-extinguishing after 65 washing cycles, and the in-situ deposition of insoluble three-dimensional polycondensation compounds onto the T/C blend fabrics was beneficial. The flame-retardant coating had a minor impact on the whiteness, tensile strength and breathability of the T/C blend fabrics.

Structural, mechanical and in vitro studies on pulsed laser deposition of hydroxyapatite on additive manufactured polyamide substrate

Additive manufacturing (AM) is an emerging field that merges engineering and life sciences to produce components that can effectively act as a replacement in the human body. This AM encompasses biofabrication using cells, biological or biomaterials as building blocks to fabricate biological and bio-application oriented substance, device and therapeutic products through a broad range of engineering and biological processes. Furthermore, bioactive coating on BAM surface facilitates biological fixation between the prosthesis and the hard tissue which increases the long term stability and integrity of the implant. In this paper, hydroxyapatite (HA) powder was coated over AM polyamide substrate using pulsed laser deposition. Coating morphology was characterised using scanning electron microscope (SEM) analysis and observed that the coating was dominated by the presence of particle droplet with different sizes. Compounds like tricalcium phosphate and a few amorphous calcium phosphates were found along with HA which was confirmed by X-ray diffraction (XRD) analysis. Fourier transform infrared spectroscopy (FTIR) techniques shows the presence of phosphate and carbonate groups in the HA structure. Nano-indentation and pull-out test reveals that the layer was strong enough and withstands higher load before it peels off. In vitro analysis was evaluated with human osteosarcoma MG-63 cells with respect to the cell viability and results shows that the good viability was observed on coated surface due to combinational effect of Ca2+ and PO4 3− ions. The multitude of characterisation conducted on the coating has established that coating polyamide with HA results in a positive combination for an implant.