Employing functionalized graphene quantum dots to combat coronavirus and enterovirus

The ongoing COVID-19 (i.e., coronavirus) pandemic continues to adversely affect the human life, economy, and the world's ecosystem. Although significant progress has been made in developing antiviral materials for the coronavirus, much more work is still needed. In this work, N-functionalized graphene quantum dots (GQDs) were designed and synthesized as the antiviral nanomaterial for Feline Coronavirus NTU156 (FCoV NTU156) and Enterovirus 71 (EV71)) with ultra-high inhibition (>99.9%). To prepare the GQD samples, a unique solid-phase microwave-assisted technique was developed and the cell toxicity was established on the H171 and H184 cell lines after 72 h incubation, indicating superior biocompatibility. The surface functionality of GQDs (i.e., the phenolic and amino groups) plays a vital role in interacting with the receptor-binding-domain of the spike protein. It was also found that the addition of polyethylene glycol is advantageous for the dispersion and the adsorption of functionalized GQDs onto the virus surface, leading to an enhanced virus inhibition. The functionality of as-prepared GQD nanomaterials was further confirmed where a functionalized GQD-coated glass was shown to be extremely effective in hindering the virus spread for a relatively long period (>20 h).

Unveiling the catalytic ability of carbonaceous materials in Fenton-like reaction by controlled-release CaO2 nanoparticles for trichloroethylene degradation

Carbonaceous materials (CMs) have been applied extensively for enhancing the catalytic performance of environmental catalysts, however, the self-catalytic mechanism of CMs for groundwater remediation is rarely investigated. Herein, we unveiled the catalytic ability of various CMs via Fe(III) reduction through polyvinyl alcohol-coated calcium peroxide nanoparticles (PVA@nCP) for trichloroethylene (TCE) removal. Among selected CMs (graphite (G), biochar (BC) and activated carbon (AC)), BC and AC showed enhancement of TCE removal of 89% and 98% via both adsorption and catalytic degradation. BET and SEM analyses showed a higher adsorption capacity of AC (27.8%) than others. The generation of solution-Fe(II) and surface-Fe(II) revealed the reduction of Fe(III) on CMs-surface. The role of O-containing groups was investigated by the FTIR technique and XPS quantified the 52% and 57% surface-Fe(II) in BC and AC systems, respectively. EPR and quenching tests confirmed that both solution and surface-bound species (HO•, O₂^-• and ¹O₂) contributed to TCE degradation. Acidic pH condition encouraged TCE removal and the presence of HCO₃^- negatively affected TCE removal than other inorganic ions. Both schemes (PVA@nCP/Fe(III)/BC and PVA@nCP/Fe(III)/AC) exhibited promising results in the actual groundwater, surfactant-amended solution, and removal of other chlorinated-pollutants, opening a new direction towards green environmental remediation for prolonged benefits.

Sustainable preparation of bifunctional cellulose nanocrystals via mixed H2SO4/formic acid hydrolysis

In this work, a sustainable and highly efficient approach for preparing bifunctional cellulose nanocrystals (CNCs) was proposed through a mixed acid system of sulfuric acid and formic acid (FA). It was found that low-concentration (5-10 wt%) sulfuric acid can significantly improve the hydrolysis efficiency of FA (65-80 wt%), which enabled the highly efficient preparation of CNCs, i.e., the maximum yield of CNCs reached up to 70.65%. The obtained CNCs exhibited a rod-like shape with high crystallinity, and good dispersibility in both water and some organic phases. Moreover, the as-prepared CNCs exhibited high thermal stability, which is much higher than that of the traditionally sulfuric acid hydrolyzed ones. In addition, it was demonstrated that the bifunctional CNCs were able to stabilize various oils to form stable Pickering emulsion gels. Thus, this work provides a promising approach for sustainable preparation of bifunctional CNCs, which may find high-end applications in diverse fields.

Efficient removal of diclofenac from surface water by the functionalized multilayer magnetic adsorbent: Kinetics and mechanism

Developing robust and effective adsorbent for removing ubiquitous pharmaceutical diclofenac (DCF) from the aquatic environment is vitally important for environmental safety. Hence, a novel chitosan-based multilayer adsorbent (FCS-PD) with magnetic separation ability and surface functionality was successfully assembled, which had countless potential for removing contaminants from water. A series of instrumental technologies were performed to demonstrate the physicochemical properties of FCS-PD. Its adsorption performance toward DCF removal was comprehensively evaluated in synthetic water and surface water. The effects of microplastics, inorganic ions and humic acid on the adsorption were investigated. The maximum adsorption capacity of FCS-PD was calculated as 434.78 mg/g under neutral conditions, exhibiting superior adsorption performance than most reported adsorbents. The DCF in surface water was practically removed at low concentration (50 μg/L). FCS-PD presented a multistage kinetics controlled by chemisorption and intraparticle diffusion, which was emphasized by the pseudo-second-order kinetic and intra-particle diffusion analysis. After five cycles of adsorption and regeneration, the adsorption capacity only decreased by 9.9%, indicating the satisfactory regeneration of FCS-PD. The analysis of high-resolution X-ray photoelectron spectroscopic (XPS) and Fourier transform infrared spectroscopy (FTIR) revealed that the quaternary ammonium groups on the outer layer and the amino and hydroxyl groups on the chitosan layer are involved in the capture of DCF under electrostatic force and hydrogen bonding.

The effect of augmentation of biochar and hydrochar in anaerobic digestion of a model substrate

The augmentation of biochar produced at 450 and 600-650 °C and hydrochar produced at 250 °C has been investigated using biochemical methane potential experiments of cellulose. The feedstocks used for the char production included the lignocellulosic (oak wood), macroalgae (Fucus serratus) and aquatic plant (water hyacinth). Biomethane production was improved with the addition of lower-temperature biochars from oak wood (285 mL CH₄/g VS) and water hyacinth (294 mL CH₄/g VS), corresponding to 7 and 11% more than the control. The addition of these two biochars increased the methane production rate of 2.4 and 2.3 times the control, respectively. Higher temperature biochars showed no difference. Conversely, all hydrochars and macroalgae biochars augmentation reduced methane generation by 57-86 %. The chemical and structural composition of each of the chars differed significantly. Surface oxygen functionality appears to be the most important property of the biochars that improved digestion performance.

Effect of surface functionality of molecularly imprinted composite nanospheres on specific recognition of proteins

The surface functionality of biomaterial plays a primary role in determining its application in biorecognition and drug delivery. In our work, three types of synthetic tailoring polymer nanospheres with hierarchical architecture were constructed to obtain functional polymer layer with disparate chemical motifs for protein adsorption via surface imprinting and grafting copolymerization. In this polymerization system, the structure stability of template protein bovine serum albumin (BSA) is well maintained within a certain range, which facilitated the accurate imprinting and precise identification. A comprehensive protocol for screening different functional layer is proposed through comparing the adsorption behavior, selectivity, identification and responsiveness to medium pH of three functional layers. Our study demonstrates that surface functionality greatly influences the adsorption capacity and selectivity of adsorption material. The functional layer with ionic liquid structure that could only provide multiple non-covalent binding sites is beneficial to the proteins aggregation and extraction, while the anti-nonspecific binding functional layer of biomaterial with zwitterionic structure for specific protein capture is promising to serve as a preferable antigen-antibody communication network, which shows great potential for protein recognition and separation. In summary, our proposed strategy provides a systematic selection criterion of biomaterials for effective application in biosensors.

Role of surface functionalities of nanoplastics on their transport in seawater-saturated sea sand

The transport and retention of nanoplastics (NP, 200 nm nanopolystyrene) functionalized with surface carboxyl (NPC), sulfonic (NPS), low-density amino (negatively charged, NPA^-), and high-density amino (positively charged, NPA⁺) groups in seawater-saturated sand with/without humic acid were examined to explore the role of NP surface functionalities. The mass percentages of NP recovered from the effluent (M_eff) with a salinity of 35 practical salinity units (PSU) were ranked as follows: NPC (19.69%) > NPS (16.37%) > NPA⁺ (13.33%) > NPA^- (9.78%). The homoaggregation of NPS and NPA^- was observed in seawater. The transport of NPA^- exhibited a ripening phenomenon (i.e., a decrease in the transport rate with time) due to the high attraction of NP with previously deposited NP, whereas monodispersed NPA⁺ presented a low M_eff value because of the electrostatic attraction between NPA⁺ and negatively charged sand. Retention experiments showed that the majority of NPC, NPS and NPA⁺ accumulated in a monolayer on the sand surface, whereas NPA^- accumulated in multiple layers. Suwannee River humic acid (SRHA) could remarkably improve the transportability of NPC, NPS, and NPA^- by increasing steric repulsion. The strong attraction between NPA⁺ and the deposited NPA⁺ in the presence of SRHA triggered the weak ripening phenomenon. As seawater salinity decreased from 35 PSU to 3.5 PSU, the increase in electrostatic repulsion of NP-NP and NP-sand enhanced the transport of NPC, NPS, and NPA^-, and the ripening of NPA^- breakthrough curves disappeared. In deionized water, NPC, NPS, and NPA^- achieved complete column breakthrough because the electrostatic repulsion between NP and sand intensified. However, the M_eff values of NPA⁺ in 3.5 PSU seawater and deionized water presented limited increments of 15.49% and 23.67%, respectively. These results indicated that the fate of NP in sandy marine environments were strongly affected by NP surface functionalities, seawater salinity, and coexisting SRHA.

Development of carbon adsorbents with high surface acidity and basicity from polyhydric alcohols with phosphoric acid activation for Ni(II) removal

In this study, polyhydric alcohols, including glycerol, erythritol, xylitol, mannitol, and inositol, were chosen as carbon precursors for preparation of carbon adsorbents via phosphoric acid activation. The thermal behaviors of phosphoric acid-treated polyhydric alcohols revealed the formation and decomposition of organic phosphates at low temperatures, which enhanced the creation of functional groups on activated carbon. In general, the activated carbons showed relative low surface area (the highest one of 509 m²/g for AC-xylitol) due to the low activation temperature, and low yields (the highest one of 36.6% for AC-xylitol) due to the volatilization and decomposition of organic phosphates. The activated carbons contained 50-90% larger total amount of surface groups than the reference activated carbon derived from lignocellulose material, which mainly resulted in their 40-75% higher Ni(II) adsorption capacity. These results also indicated that the polyhydric alcohols-based activated carbons can be promising candidates for Ni(II) removal.

Design of polymer particle dispersions (latexes) in the course of radical heterophase polymerization for biomedical applications

Dispersions of polymer particle (DPPs) are increasingly being exploited both as biomolecule carriers, and as markers in various DPP biomedical applications related to cell and molecular biology, enzymology, immunology, diagnostics, in vitro and in vivo visualization, bioseparation, etc. Their potential to reduce reaction scales, lower costs, improve the rate, sensitivity, selectivity, stability and reproducibility of assays governs the diversity of their bioapplications. This review focuses on the design of DPPs with innovative special properties in the course of free radical heterophase polymerization that provides careful control of both macromolecular and colloidal properties. We demonstrate approaches that, according to the polymerization technique, regulate the particle size, shape, particle size distribution, morphology, surface chemistry and functionality, as well as the formation of organic-inorganic hybrid DPPs. The production of bioreagents based on DPPs and their use in bioassay are also reviewed.

Removal of Tetrabromobisphenol A by adsorption on pinecone-derived activated charcoals: Synchrotron FTIR, kinetics and surface functionality analyses

This study explored the adsorption of Tetrabromobisphenol A (TBBPA) on pinecone-derived activated charcoal. The interactions between TBBPA and activated-charcoal surface, as well as the corresponding effects of functionality and adsorption capacities, were investigated through synchrotron FTIR, kinetics and surface functionality analyses. It was found that multiple acid functional groups and their interactive effects played important roles. The adsorption on activated charcoal from Yellow pinecone was favored by the surface with high polarity, low aromaticity, and low surface area. In comparison, adsorption on activated charcoal from Scot pinecone was favored by the surface with high aromaticity and high surface area. The adsorption capacity and removal efficiency were significantly dependent upon the contents of acid functional groups on charcoal surface. This study showed that the newly presented evidence of interactions between oxygen-containing functional groups and TBBPA will be helpful for exploring the treatment and transport of such a contaminant in the environment.

Insights into the attenuated sorption of organic compounds on black carbon aged in soil

Sorption of organic compounds on fresh black carbons (BCs) can be greatly attenuated in soil over time. We examined herein the changes in surface properties of maize straw-derived BCs (biochars) after aged in a black soil and their effects on the sorptive behaviors of naphthalene, phenanthrene and 1,3-dinitrobenzene. Dissolved fulvic and humic acids extracted from the soil were used to explore the role of dissolved organic carbon (DOC) in the aging of biochars. Chromatography analysis indicated that DOC molecules with relatively large molecular weight were preferentially adsorbed on the biochars during the aging processes. DOC sorption led to blockage of the biochar's micropores according to N₂ and CO₂ adsorption analyses. Surface chemistry of the biochars was also substantially modified, with more O-rich functional groups on the aged biochars compared to the original biochars, as evidenced by Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses. The changes in both the physical and chemical surface properties of biochars by DOC led to significant attenuation of the sorption capacity and nonlinearity of the nonionic organic compounds on the aged biochars. Among the tested organic compounds, phenanthrene was the most attenuated in its sorption by the aging treatments, possibly because of its relatively large molecular size and hydrophobicity. The information can help gain a mechanistic understanding of interactions between BCs and organic compounds in soil environment.

Surface functionality affects the biodistribution and microglia-targeting of intra-amniotically delivered dendrimers

Cerebral Palsy (CP) is a chronic childhood disorder with limited therapeutic options. Maternal intrauterine inflammation/infection is a major risk factor in the pathogenesis of CP. In pre-clinical models, dendrimer-based therapies are viable in postnatal period, attenuating inflammation and improving motor function in vivo. However, treatment to the mother, in the prenatal period, may provide the possibility of preventing/resolving inflammation at early stages. Towards this goal, we used a maternal intrauterine inflammation-induced rabbit model of CP to study fetal-maternal transport and neuroinflammation targeting of intra-amniotically administrated dendrimers with neutral/anionic surface functionality. Our study suggested both hydroxyl-terminated 'neutral' (D-OH) and carboxyl-terminated 'anionic' (D-COOH) Polyamidoamine (PAMAM) dendrimers were absorbed by fetuses and demonstrated bi-directional transport between fetuses and mother. D-OH was more effective in crossing the fetal blood-brain barrier, and targeting activated microglia. The cell-specific targeting was associated with the extent of microglia activation. This study demonstrated intra-amniotically administered hydroxyl PAMAM dendrimers could be an effective drug delivery vehicle for targeting fetal inflammation and preventing subsequent neurologic injury associated with chorioamnionitis.

Chemical forms of the fluorine, chlorine, oxygen and carbon in coal fly ash and their correlations with mercury retention

Fly ashes recovered from the particulate control devices at six pulverized coal boiler unites of China, are studied using an X-ray photoelectron spectroscopy (XPS) with a particular focus on the functionalities of fluorine (F), chlorine (Cl), carbon and oxygen on fly ash. It is found that the inorganic forms of F and Cl are predominant on the ash surface in comparison with their organics, and the proportion of organic Cl is relatively higher than that of organic F. Similar results are also obtained in the bulk by correlating the F and Cl contents with those of the unburnt carbon and other compositions in ash. Strong correlations of mercury retention with surface carbon-oxygen functional groups indicate that the C=O, OH/C-O and (O-C=O)-O on surface are of significant importance for mercury retention in fly ash. Their surface concentrations are related to coal type. The presence of Cl in fly ash helps with mercury retention. No obvious effect of F is observed.