Modeling Ion Transport across Thin-Film Composite Membranes During Saltwater Electrolysis.

Affordable thin-film composite (TFC) membranes are a potential alternative to more expensive ion exchange membranes in saltwater electrolyzers used for hydrogen gas production. We used a solution-friction transport model to study how the induced potential gradient controls ion transport across the polyamide (PA) active layer and support layers of TFC membranes during electrolysis. The set of parameters was simplified by assigning the same size-related partition and friction coefficients for all salt ions through the membrane active layer. The model was fit to experimental ion transport data from saltwater electrolysis with 600 mM electrolytes at a current density of 10 mA cm-2. When the electrolyte concentration and current density were increased, the transport of major charge carriers was successfully predicted by the model. Ion transport calculated using the model only minimally changed when the negative active layer charge density was varied from 0 to 600 mM, indicating active layer charge was not largely responsible for controlling ion crossover during electrolysis. Based on model simulations, a sharp pH gradient was predicted to occur within the supporting layer of the membrane. These results can help guide membrane design and operation conditions in water electrolyzers using TFC membranes.

Using a non-precious metal catalyst for long-term enhancement of methane production in a zero-gap microbial electrosynthesis cell.

Microbial electrosynthesis (MES) cells exploit the ability of microbes to convert CO2 into valuable chemical products such as methane and acetate, but high rates of chemical production may need to be mediated by hydrogen and thus require a catalyst for the hydrogen evolution reaction (HER). To avoid the usage of precious metal catalysts and examine the impact of the catalyst on the rate of methane generation by microbes on the electrode, we used a carbon felt cathode coated with NiMo/C and compared performance to a bare carbon felt or a Pt/C-deposited cathode. A zero-gap configuration containing a cation exchange membrane was developed to produce a low internal resistance, limit pH changes, and enhance direct transport of H2 to microorganisms on the biocathode. At a fixed cathode potential of -1 V vs Ag/AgCl, the NiMo/C biocathode enabled a current density of 23 ± 4 A/m2 and a high methane production rate of 4.7 ± 1.0 L/L-d. This performance was comparable to that using a precious metal catalyst (Pt/C, 23 ± 6 A/m2, 5.4 ± 2.8 L/L-d), and 3-5 times higher than plain carbon cathodes (8 ± 3 A/m2, 1.0 ± 0.4 L/L-d). The NiMo/C biocathode was operated for over 120 days without observable decay or severe cathode catalyst leaching, reaching an average columbic efficiency of 53 ± 9 % based on methane production under steady state conditions. Analysis of microbial community on the biocathode revealed the dominance of the hydrogenotrophic genus Methanobacterium (∼40 %), with no significant difference found for biocathodes with different materials. These results demonstrated that HER catalysts improved rates of methane generation through facilitating hydrogen gas evolution to an attached biofilm, and that the long-term enhancement of methane production in MES was feasible using a non-precious metal catalyst and a zero-gap cell design.

Thin-Film Composite Membranes for Hydrogen Evolution with a Saline Catholyte Water Feed.

Hydrogen gas evolution using an impure or saline water feed is a promising strategy to reduce overall energy consumption and investment costs for on-site, large-scale production using renewable energy sources. The chlorine evolution reaction is one of the biggest concerns in hydrogen evolution with impure water feeds. The "alkaline design criterion" in impure water electrolysis was examined here because water oxidation catalysts can exhibit a larger kinetic overpotential without interfering chlorine chemistry under alkaline conditions. Here, we demonstrated that relatively inexpensive thin-film composite (TFC) membranes, currently used for high-pressure reverse osmosis (RO) desalination applications, can have much higher rejection of Cl- (total crossover of 2.9 ± 0.9 mmol) than an anion-exchange membrane (AEM) (51.8 ± 2.3 mmol) with electrolytes of 0.5 M KOH for the anolyte and 0.5 M NaCl for the catholyte with a constant current (100 mA/cm2 for 20 h). The membrane resistances, which were similar for the TFC membrane and the AEM based on electrochemical impedance spectroscopy (EIS) and Ohm's law methods, could be further reduced by increasing the electrolyte concentration or removal of the structural polyester supporting layer (TFC-no PET). TFC membranes could enable pressurized gas production, as this membrane was demonstrated to be mechanically stable with no change in permeate flux at 35 bar. These results show that TFC membranes provide a novel pathway for producing green hydrogen with a saline water feed at elevated pressures compared to systems using AEMs or porous diaphragms.

Reducing Chloride Ion Permeation during Seawater Electrolysis Using Double-Polyamide Thin-Film Composite Membranes.

Low-cost polyamide thin-film composite membranes are being explored as alternatives to expensive cation exchange membranes for seawater electrolysis. However, transport of chloride from seawater to the anode chamber must be reduced to minimize the production of chlorine gas. A double-polyamide composite structure was created that reduced the level of chloride transport. Adding five polyamide layers on the back of a conventional polyamide composite membrane reduced the chloride ion transport by 53% and did not increase the applied voltage. Decreased chloride permeation was attributed to enhanced electrostatic and steric repulsion created by the new polyamide layers. Charge was balanced through increased sodium ion transport (52%) from the anolyte to the catholyte rather than through a change in the transport of protons and hydroxides. As a result, the Nernstian loss arising from the pH difference between the anolyte and catholyte remained relatively constant during electrolysis despite membrane modifications. This lack of a change in pH showed that transport of protons and hydroxides during electrolysis was independent of salt ion transport. Therefore, only sodium ion transport could compensate for the reduction of chloride flux to maintain the set current. Overall, these results prove the feasibility of using a double-polyamide structure to control chloride permeation during seawater electrolysis without sacrificing energy consumption.

Rapid, Selective, and Chemical-Free Removal of Dissolved Silica from Water via Electrosorption: Feasibility and Mechanisms.

The unavoidable and detrimental formation of silica scale in engineered processes necessitates the urgent development of effective, economic, and sustainable strategies for dissolved silica removal from water. Herein, we demonstrate a rapid, chemical-free, and selective silica removal method using electrosorption. Specifically, we confirm the feasibility of exploiting local pH dynamics at the electrodes in flow-through electrosorption, achieved through a counterintuitive cell configuration design, to induce ionization and concomitant electrosorption of dissolved silica. In addition, to improve the feasibility of silica electrosorption under high-salinity solutions, we developed a silica-selective anode by functionalizing porous activated carbon cloths with aluminum hydroxide nanoparticles (Al(OH)3-p-ACC). The modification markedly enhances silica sorption capacity (2.8 vs 1.1 mgsilica ganode-1) and reduces the specific energy consumption (13.3 vs 19.8 kWh kgsilica-1). Notably, the modified electrode retains remarkable silica sorption capacity even in the presence of high concentrations of co-occurring ions (up to 100 mM NaCl). The mechanisms underlying the superior silica removal stability and selectivity with the Al(OH)3-p-ACC electrode are also elucidated, revealing a synergistic interaction involving outer-sphere and inner-sphere complexation between dissolved silica and Al(OH)3 nanoparticles on the electrodes. Moreover, we find that effective regeneration of the electrodes may be achieved by applying a reverse potential during discharge, although complete regeneration of the modified electrodes may necessitate alternative materials or process optimization. We recommend the adoption of feedwater-specific designs for the development of future silica-selective electrodes in electrosorption capable of meeting silica removal demands across a wide range of engineered systems.

Ceramic thin-film composite membranes with tunable subnanometer pores for molecular sieving.

Ceramic membranes are a promising alternative to polymeric membranes for selective separations, given their ability to operate under harsh chemical conditions. However, current fabrication technologies fail to construct ceramic membranes suitable for selective molecular separations. Herein, we demonstrate a molecular-level design of ceramic thin-film composite membranes with tunable subnanometer pores for precise molecular sieving. Through burning off the distributed carbonaceous species of varied dimensions within hybrid aluminum oxide films, we created membranes with tunable molecular sieving. Specifically, the membranes created with methanol showed exceptional selectivity toward monovalent and divalent salts. We attribute this observed selectivity to the dehydration of the large divalent ions within the subnanometer pores. As a comparison, smaller monovalent ions can rapidly permeate with an intact hydration shell. Lastly, the flux of neutral solutes through each fabricated aluminum oxide membrane was measured for the demonstration of tunable separation capability. Overall, our work provides the scientific basis for the design of ceramic membranes with subnanometer pores for molecular sieving using atomic layer deposition.

Relative Insignificance of Polyamide Layer Selectivity for Seawater Electrolysis Applications.

Low-cost polyamide thin-film composite (TFC) membranes are being explored as alternatives to cation exchange membranes for seawater electrolysis. An optimal membrane should have a low electrical resistance to minimize applied potentials needed for water electrolysis and be able to block chloride ions present in a seawater catholyte from reaching the anode. The largest energy loss associated with a TFC membrane was the Nernstian overpotential of 0.74 V (equivalent to 37 Ω cm2 at 20 mA cm-2), derived from the pH difference between the anolyte and catholyte and not the membrane ohmic overpotential. Based on analysis using electrochemical impedance spectroscopy, the pristine TFC membrane contributed only 5.00 Ω cm2 to the ohmic resistance. Removing the polyester support layer reduced the resistance by 79% to only 1.04 Ω cm2, without altering the salt ion transport between the electrolytes. Enlarging the pore size (∼5 times) in the polyamide active layer minimally impacted counterion transport across the membrane during electrolysis, but it increased the total concentration of chloride transported by 60%. Overall, this study suggests that TFC membranes with thinner but mechanically strong supporting layers and size-selective active layers should reduce energy consumption and the potential for chlorine generation for seawater electrolyzers.

Free-standing membrane incorporating single-atom catalysts for ultrafast electroreduction of low-concentration nitrate.

The release of wastewaters containing relatively low levels of nitrate (NO3-) results in sufficient contamination to induce harmful algal blooms and to elevate drinking water NO3- concentrations to potentially hazardous levels. In particular, the facile triggering of algal blooms by ultra-low concentrations of NO3- necessitates the development of efficient methods for NO3- destruction. However, promising electrochemical methods suffer from weak mass transport under low reactant concentrations, resulting in long treatment times (on the order of hours) for complete NO3- destruction. In this study, we present flow-through electrofiltration via an electrified membrane incorporating nonprecious metal single-atom catalysts for NO3- reduction activity enhancement and selectivity modification, achieving near-complete removal of ultra-low concentration NO3- (10 mg-N L-1) with a residence time of only a few seconds (10 s). By anchoring Cu single atoms supported on N-doped carbon in a carbon nanotube interwoven framework, we fabricate a free-standing carbonaceous membrane featuring high conductivity, permeability, and flexibility. The membrane achieves over 97% NO3- removal with high N2 selectivity of 86% in a single-pass electrofiltration, which is a significant improvement over flow-by operation (30% NO3- removal with 7% N2 selectivity). This high NO3- reduction performance is attributed to the greater adsorption and transport of nitric oxide under high molecular collision frequency coupled with a balanced supply of atomic hydrogen through H2 dissociation during electrofiltration. Overall, our findings provide a paradigm of applying a flow-through electrified membrane incorporating single-atom catalysts to improve the rate and selectivity of NO3- reduction for efficient water purification.

Discovery of linear unnatural peptides as potent mutant isocitrate dehydrogenase 1 inhibitors by Ugi reaction.

Isocitrate dehydrogenases 1 (IDH1) catalyzes the oxidative decarboxylation of isocitrate to ɑ-ketoglutaric acid (α-KG). It is the most frequently mutated metabolic gene in human cancer and its mutations interfere with cell metabolism and epigenetic regulation, thus promoting tumorigenesis. In order to discover potent new mutant IDH1 inhibitors, based on the structure of marketed inhibitor AG-120 (Ivosidenib), we designed, synthesized and evaluated a series of linear unnatural peptide analogues via Ugi reaction, as potential mutant IDH1 inhibitors. All these compounds were evaluated for their inhibition on mutant IDH1 enzyme activity. The structure-activity relationship was discussed on the basis of experimental data, with an attempt to pave the way for future studies. Among them, 43 exhibited potent and selective enzyme inhibitory activity, and showed strong binding affinity with mutant IDH1. It can decrease the cellular concentration of 2-HG, and suppress the proliferation of HT1080 and IDH1 mutant-U-87 cells by selectively inhibiting the activity of mutant IDH1.

Selective Fluoride Transport in Subnanometer TiO2 Pores.

Synthesizing nanopores which mimic the functionality of ion-selective biological channels has been a challenging yet promising approach to advance technologies for precise ion-ion separations. Inspired by the facilitated fluoride (F-) permeation in the biological fluoride channel, we designed a highly fluoride-selective TiO2 film using the atomic layer deposition (ALD) technique. The subnanometer voids within the fabricated TiO2 film (4 Å < d < 12 Å, with two distinct peaks at 5.5 and 6.5 Å), created by the hindered diffusion of ALD precursors (d = 7 Å), resulted in more than eight times faster permeation of sodium fluoride compared to other sodium halides. We show that the specific Ti-F interactions compensate for the energy penalty of F- dehydration during the partitioning of F- ions into the pore and allow for an intrapore accumulation of F- ions. Concomitantly, the accumulation of F- ions on the pore walls also enhances the transport of sodium (Na+) cations due to electrostatic interactions. Molecular dynamics simulations probing the ion concentration and mobility within the TiO2 pore further support our proposed mechanisms for the selective F- transport and enhanced Na+ permeation in the TiO2 film. Overall, our work provides insights toward the design of ion-selective nanopores using the ALD technique.

Chemical Components of the Fruits of Morus nigra Linn.: Methyl Caffeate as a Potential Anticancer Agent by Targeting 3-Phosphoglycerate Dehydrogenase.

Two previously undescribed compounds, moranigrine A (1) and morusamine (2), along with 18 known compounds were isolated from the fruits of Morus nigra Linn. and structurally characterized using spectroscopic data and electronic circular dichroism analyses. All isolates were evaluated for their inhibitory effects on the 3-phosphoglycerate dehydrogenase (PHGDH) enzyme, which catalyzes the first committed step for the synthesis of glucose-derived serine and is associated with many kinds of cancers. Among these compounds, methyl caffeate (3) exhibited effective inhibition against PHGDH and was directly bound to PHGDH based on the microscale thermophoresis method and the cellular thermal shift assay. Further biochemical assays revealed that 3 was a noncompetitive inhibitor with respect to the substrate of 3-phosphoglycerate and exhibited a concentration-dependent inhibition. Molecular docking demonstrated that 3 coordinated in an allosteric site of PHGDH with low binding energy. Meanwhile, 3 was selectively toxic to high PHGDH-expressing cancer cell lines and could cause apoptosis of cervical cancer cells in micromolar concentrations and could obviously inhibit tumor growth in the HeLa xenograft mouse model with low toxicities. Therefore, 3 could be developed as a potential inhibitor of PHGDH for the treatment of cancers. Our present study provides information about M. nigra as a functional food or pharmaceutical supplement in the application of cancer prevention and treatment.

Elucidating the Role of Single-Atom Pd for Electrocatalytic Hydrodechlorination.

In this study, we loaded Pd catalysts onto a reduced graphene oxide (rGO) support in an atomically dispersed fashion [i.e., Pd single-atom catalysts (SACs) on rGO or Pd1/rGO] via a facile and scalable synthesis based on anchor-site and photoreduction techniques. The as-synthesized Pd1/rGO significantly outperformed the Pd nanoparticle (Pdnano) counterparts in the electrocatalytic hydrodechlorination of chlorinated phenols. Downsizing Pdnano to Pd1 leads to a substantially higher Pd atomic efficiency (14 times that of Pdnano), remarkably reducing the cost for practical applications. The unique single-atom architecture of Pd1 additionally affects the desorption energy of the intermediate, suppressing the catalyst poisoning by Cl-, which is a prevalent challenge with Pdnano. Characterization and experimental results demonstrate that the superior performance of Pd1/rGO originates from (1) enhanced interfacial electron transfer through Pd-O bonds due to the electronic metal-support interaction and (2) increased atomic H (H*) utilization efficiency by inhibiting H2 evolution on Pd1. This work presents an important example of how the unique geometric and electronic structure of SACs can tune their catalytic performance toward beneficial use in environmental remediation applications.

Rational Design and Synthesis of Novel Dual PROTACs for Simultaneous Degradation of EGFR and PARP.

Inspired by the success of dual-targeting drugs, especially bispecific antibodies, we propose to combine the concept of proteolysis targeting chimera (PROTAC) and dual targeting to design and synthesize dual PROTAC molecules with the function of degrading two completely different types of targets simultaneously. A library of novel dual-targeting PROTAC molecules has been rationally designed and prepared. A convergent synthetic strategy has been utilized to achieve high synthetic efficiency. These dual PROTAC structures are characterized using trifunctional natural amino acids as star-type core linkers to connect two independent inhibitors and E3 ligands together. In this study, gefitinib, olaparib, and CRBN or VHL E3 ligands were used as substrates to synthesize novel dual PROTACs. They successfully degraded both the epidermal growth factor receptor (EGFR) and poly(ADP-ribose) polymerase (PARP) simultaneously in cancer cells. Being the first successful example of dual PROTACs, this technique will greatly widen the range of application of the PROTAC method and open up a new field for drug discovery.

Precisely Engineered Photoreactive Titanium Nanoarray Coating to Mitigate Biofouling in Ultrafiltration.

To combat biofouling on membranes, diverse nanostructures of titanium dioxide (TiO2) have emerged as effective antimicrobial coatings due to TiO2's abilities to transport charge and photoinduce oxidation. However, TiO2 composite polymeric membranes synthesized using traditional methods of growing crystals have proven chemically unstable, with loss of coating and diminishing antimicrobial performance. Thus, new fabrication methods to enhance durability and efficacy should be considered. In this work, we propose a stepwise approach to construct a stable, uniform TiO2 nanoarray of regularly spaced, aligned crystals on the surface of a polytetrafluoroethylene ultrafiltration membrane using precisely controlled atomic layer deposition (ALD) followed by solvothermal deposition. We demonstrate that ALD can uniformly seed TiO2 nanoparticles on the membrane surface with atomic-scale precision. Subsequently, solvothermal deposition assembles and aligns a uniform TiO2 nanoarray forest. In the presence of sunlight, this TiO2 nanoarray effectively inactivates any deposited bacteria, increasing flux recovery after membrane cleaning. By systematically investigating this antimicrobial activity, we found that TiO2 both physically damages cell membranes as well as produces reactive oxygen species in the presence of sunlight that inactivate bacteria. Our study provides an effective bottom-up synthesis scheme to optimize and tailor antifouling TiO2 coatings for ultrafiltration and other surfaces for a wide range of applications.

Cobalt Single Atoms on Tetrapyridomacrocyclic Support for Efficient Peroxymonosulfate Activation.

Transition-metal catalysts that can efficiently activate peroxide bonds have been extensively pursued for various applications including environmental remediation, chemical synthesis, and sensing. Here, we present pyridine-coordinated Co single atoms embedded in a polyaromatic macrostructure as a highly efficient peroxide-activation catalyst. The efficient catalytic production of reactive radicals through peroxymonosulfate activation was demonstrated by the rapid removal of model aqueous pollutants of environmental and public health concerns such as bisphenol A, without pH limitation and Co2+ leaching. The turnover frequency of the newly synthesized Co single-atom catalyst bound to tetrapyridomacrocyclic ligands was found to be 2 to 4 orders of magnitude greater than that of benchmark homogeneous (Co2+) and nanoparticulate (Co3O4) catalysts. Experimental results and density functional theory simulation suggest that the abundant π-conjugation in the polyaromatic support and strong metal-support electronic interaction allow the catalysts to effectively adsorb and activate the peroxide precursor. We further loaded the catalysts onto a widely used poly(vinylidene fluoride) microfiltration membrane and demonstrated that the model pollutants were oxidatively removed as they simply passed through the filter, suggesting the promise of utilizing this novel catalyst for realistic applications.

Intrapore energy barriers govern ion transport and selectivity of desalination membranes.

State-of-the-art desalination membranes exhibit high water-salt selectivity, but their ability to discriminate between ions is limited. Elucidating the fundamental mechanisms underlying ion transport and selectivity in subnanometer pores is therefore imperative for the development of ion-selective membranes. Here, we compare the overall energy barrier for salt transport and energy barriers for individual ion transport, showing that cations and anions traverse the membrane pore in an independent manner. Supported by density functional theory simulations, we demonstrate that electrostatic interactions between permeating counterion and fixed charges on the membrane substantially hinder intrapore diffusion. Furthermore, using quartz crystal microbalance, we break down the contributions of partitioning at the pore mouth and intrapore diffusion to the overall energy barrier for salt transport. Overall, our results indicate that intrapore diffusion governs salt transport through subnanometer pores due to ion-pore wall interactions, providing the scientific base for the design of membranes with high ion-ion selectivity.

Mechanism of Heterogeneous Fenton Reaction Kinetics Enhancement under Nanoscale Spatial Confinement.

Nanoscale catalysts that can enable Fenton-like chemistry and produce reactive radicals from hydrogen peroxide activation have been extensively studied in order to overcome the limitations of homogeneous Fenton processes. Despite several advantageous features, limitation in mass transfer of short-lived radical species is an inherent drawback of the heterogeneous system. Here, we present a mechanistic foundation for the way spatial confinement of Fenton chemistry at the nanoscale can significantly enhance the kinetics of radical-mediated oxidation reactions-pollutant degradation in particular. We synthesized a series of Fe3O4-functionalized nanoreactors with precise pore dimensions, based on an anodized aluminum oxide template, to enable quantitative analysis of nanoconfinement effects. Combined with computational simulation of spatial distribution of radicals, we found that hydroxyl radical concentration was strongly dependent on the distance from the surface of Fenton catalysts. This distance dependency significantly influences the gross reaction kinetics and accounts for the observed nanoconfinement effects. We further found that a length scale below 25 nm is critical to avoid the limitation of short-lived species diffusion and achieve kinetics that are orders of magnitude faster than those obtained in a batch suspension of heterogeneous catalysts. These findings suggest a new strategy to develop an innovative heterogeneous catalytic system with the most effective use of hydroxyl radicals in oxidation treatment scenarios.

Surface functionalization of reverse osmosis membranes with sulfonic groups for simultaneous mitigation of silica scaling and organic fouling.

Organic fouling and inorganic scaling are the main hurdles for efficient operation of reverse osmosis (RO) technology in a wide range of applications. This study demonstrates dual-functionality surface modification of thin-film composite (TFC) RO membranes to simultaneously impart anti-scaling and anti-fouling properties. Two different grafting approaches were adapted to functionalize the membrane surface with sulfonic groups: (i) non-specific grafting of vinyl sulfonic acid (VSA) via redox radical initiation polymerization and (ii) covalent bonding of hydroxylamide-O-sulfonic acid (HOSA) to the native carboxylic groups of the polyamide layer via carbodiimide mediated reaction. Both approaches to graft sulfonic groups were effective in increasing surface wettability and negative charge density of the TFC-RO membranes without significant alteration of water and salt permeabilities. Importantly, we verified through surface elemental analysis that covalently bound HOSA effectively covers the native carboxylic groups of the PA layer. Both the VSA and HOSA membranes exhibited lower flux decline during silica scaling and organic (alginate) fouling relative to the control unmodified membrane, demonstrating the unique versatility of sulfonic groups to endow the TFC-RO membranes with dual functionality to resist scaling and fouling. In particular, the HOSA membrane showed excellent physical cleaning efficiencies with water flux recoveries of 92.5 ± 1.0% and 88.4 ± 6.4% for silica scaling and alginate fouling, respectively. Additional results from silica nucleation experiments and atomic force measurements provided insights into the mechanisms of improved resistance to silica scaling and organic fouling imparted by the surface-functionalized sulfonic groups. Our study highlights the promise of controlled functionalization of sulfonic groups on the polyamide layer of TFC membranes to enhance the applications of RO technology in treatment and reuse of waters with high scaling and fouling potential.

Rapid Delivery of Nanobodies/VHHs into Living Cells via Expressing In Vitro-Transcribed mRNA.

Intracellular antigen labeling and manipulation by antibodies have been long-thought goals in the field of cell research and therapy. However, a central limitation for this application is that antibodies are not able to penetrate into the cytosol of living cells. Taking advantages of small sizes and unique structures of the single-domain antibodies, here, we presented a novel approach to rapidly deliver the nanobody/variable domain of heavy chain of heavy-chain antibody (VHH) into living cells via introducing its coding mRNA, which was generated by in vitro transcription. We demonstrated that actin-green fluorescent proteins (GFP) and Golgi-GFP can be recognized by the anti-GFP nanobody/VHH, vimentin can be recognized by the anti-vimentin nanobody/VHH, and histone deacetylase 6 (HDAC6) can be recognized by the anti-HDAC6 nanobody/VHH, respectively. We found that the anti-GFP nanobody expressed via in vitro-transcribed (IVT) mRNA can be detected in 3 h and degraded in 48 h after transfection, whereas the nanobody expressed via plasmid DNA, was not detected until 24 h after transfection. As a result, it is effective in delivering the nanobody through expressing the nanobody/VHH in living cells from its coding mRNA.

Controlled TiO2 Growth on Reverse Osmosis and Nanofiltration Membranes by Atomic Layer Deposition: Mechanisms and Potential Applications.

Enhancing the chemical and physical properties of the polyamide active layer of thin-film composite (TFC) membranes by surface coating is a goal long-pursued. Atomic layer deposition (ALD) has been proposed as an innovative approach to deposit chemically robust metal oxides onto membrane surfaces due to its unique capability to control coating conformality and thickness with atomic scale precision. This study examined the potential to coat the surface of TFC reverse osmosis (RO) and nanofiltration (NF) membranes via ALD of TiO2. Our results suggest that the optimal ALD conditions, the film growth kinetics, and the depth of deposition are different for RO and NF membranes due to the different diffusive transport of ALD precursors through the membrane pores. The TiO2 coating mainly located at the surface of the RO membrane; in contrast, the TiO2 coating extended to the depth of the NF membrane. The TiO2 coating degraded membrane water permeability and salt rejection beyond 10 cycles of ALD, the condition commonly employed in previous ALD-based membrane modification studies. Instead, this study showed that with fewer than 10 cycles, the TiO2 coating of RO membrane increased the membrane surface charge without negatively impacting water permeability and salt rejection. For the NF membranes, the coating of TiO2 inside their pores led to the tuning of pore sizes and increased the rejection of selected solutes.