Protonated Amine Groups Research Articles

Encapsulation of fluoxetine by cucurbit[7]uril: A computational and experimental study

Fluoxetine (FLX), a selective serotonin reuptake inhibitor, is widely prescribed for the treatment of depression and obsessive-compulsive disorders. However, the administration of FLX can lead to side effects, which may be mitigated by encapsulating the drug within a macrocyclic host. In this study, we explored the complexation of FLX with cucurbit[7]uril (CB7) using 19F and 1H NMR spectroscopy, fluorescence displacement titrations, and molecular dynamics (MD) simulations. Our fluorescence results indicate that CB7 forms a 1:1 complex with FLX, with a binding constant of 1.7 × 10³ M−1. Additionally, NMR data suggest that the (trifluoromethyl) phenyl moiety of FLX is encapsulated within the CB7 cavity. Molecular dynamics simulations revealed two binding modes for FLX with CB7: one involving the inclusion of the (trifluoromethyl) phenyl moiety and the other involving the phenyl moiety within the CB7 cavity. In both modes, the protonated amine group of FLX interacted with the CB7 portal. Binding free energy calculations using the MM-PBSA method suggested a preference for the inclusion of the phenyl moiety, which contrasts the NMR findings. The interactions between the host and guest were primarily driven by electrostatic forces, with van der Waals interactions playing a lesser, but still favorable, role. In contrast, DFT calculations produced similar binding free energy estimates for the two modes.

An Investigation of the Structures of [(Glycine)(1-Methyluracil)]M+ Complexes (M = H, Li, Na, K) in the Gas Phase by IRMPD Spectroscopy and Theoretical Methods.

The presence of ions in the complexation of molecules can profoundly affect the structure, resulting in changes to functionality and stability. These non-covalent interactions drive many biological processes both necessary and inimical and require extensive research to understand and predict their effects. Protonated and alkali metalated complexes of glycine (Gly) and 1-methyluracil (1-mUra) were studied using infrared multiphoton dissociation (IRMPD) spectroscopy and density functional theory (DFT) calculations. The experimental and simulated vibrational spectra were compared to help elucidate the structure of each complex. The lowest energy structure for [(Gly)(1-mUra)]H+ consists of amine protonated Gly bound to O4 of canonical 1-mUra through a single ionic hydrogen bond with another, intraglycine ionic hydrogen bond between the protonated amine group and the carbonyl oxygen. For [(Gly)(1-mUra)]Li+, [(Gly)(1-mUra)]Na+ and [(Gly)(1-mUra)]K+, the experimental spectra are most consistent with the metal cations binding in a trigonal planar geometry with 1-mUra bound to the metal cation via the O4 carbonyl. In [(Gly)(1-mUra)]Li+ and [(Gly)(1-mUra)]Na+, the metal cation is bound to canonical Gly via the carbonyl oxygen and amine nitrogen, but in [(Gly)(1-mUra)]K+, Gly is bound through both oxygens and contains an intraglycine hydrogen bond from the hydroxyl to the amine nitrogen.

A new strategy toward synthesis of novel bifunctional N- and S-bearing sorbent for platinum(IV) removal from aqueous solutions and acidic leaching residue of Pt/Al2O3 catalyst

Strong incentive politics have been elaborated for promoting the recovery of precious metals from secondary resources. Solid leaching generates acidic effluents that can be pre-treated using precipitation steps for partial separation before applying sorption for metal recovery from mild acidic solutions. For this purpose, a new sorbent was designed bearing numerous N- and S-bearing reactive groups with good affinity for platinum (as chloroanionic species). Thiazole precursors were first reacted before being grafted (by free radical reaction) with triallyl cyanurate (to form CTTR sorbent). The material was characterized by a series of analytical tools (SEM, BET, FTIR, XPS, TGA, elemental analysis, and titration). The effect of pH combined with FTIR and XPS spectroscopy analyses allowed identifying the mechanisms involved in metal binding: (a) electrostatic attraction of chloroplatinate anions with protonated amine groups (especially in acidic conditions), (b) while at moderate acidic pH metal sorption proceeds through ligand exchange and chelation onto N-based and S-based groups. Optimum sorption was found at pH close to 4 (near pHpzc value). Under selected experimental conditions, the equilibrium was reached in 25–35 min. The pseudo-first order rate equation fitted well experimental profile (though the resistance to intraparticle diffusion contributes to the kinetic control). The maximum sorption capacity at room temperature reached up to 1.58 mmol Pt g−1 (at pH 4). The sorption isotherm was successfully fitted by the Temkin equation. The sorption is spontaneous and exothermic (with reduction in maximum sorption capacity reaching up to 25 %, when temperature increases to 50 °C). Optimum platinum desorption was obtained with 0.3 M HCl solution (with solid/liquid ratio 1.67 g L−1) for complete desorption and enrichment factor close to 4.6. Complete desorption was maintained over 5 cycles, while the sorption efficiency decreased by less than 3.5 % at the fifth cycle. The sorbent showed remarkable stability for PGMs (Pd(II) in addition to Pt(IV)) against alkali-earth elements or base metals (from equimolar synthetic solutions); the selectivity is driven by the preference of the reactive groups (soft base and intermediary base) for soft PGM metals against hard and borderline metal ions; this selectivity is also affected by metal speciation (formation of chloro-anionic species). The valorization of platinum from non-compliant Pt/Al2O3 catalyst was investigated after leaching with aqua regia. Platinum was precipitated from the leachate with ammonium chloride. In a second step, aluminum was removed by precipitation at pH 5. The residual solution was then treated by adsorption on CTTR: optimum separation between Pt and Al was achieved at pH ≈ 3.

Facile synthesis of nitrogen-containing multiwalled carbon nanotubes as a worth metal-free electrocatalyst for hydrogen evolution reaction and semicarbazide oxidation

Studies of metal-free carbon nanostructures prove effective in energy and environmental applications due to their molecular tunability and vast chemical space. Herein, we synthesize nitrogen-containing multi-walled carbon nanotubes (N-MWCNTs) via. acid-catalysed incorporation of 3, 4-diaminopyridine into multi-walled carbon nanotubes (MWCNTs), and demonstrating their efficacy in electrocatalytic hydrogen evolution reaction (HER) and semicarbazide (SCB) oxidation for energy and environmental waste management, respectively. Successful synthesis is further confirmed by analysis techniques, i.e. Fourier transform infrared (FTIR) spectral analysis shows the diminishing OH frequency around 3250 cm−1 in MWCNTs after functionalization and the formation of an OC–NH bond in N-MWCNTs at 1710 cm−1. X-ray diffraction (XRD) confirms the incorporation of N-species, while Raman spectroscopic analysis indicates an increase in the ID/IG ratio MWCNTs (∼1) to N-MWCNTs (∼1.25), suggesting more defective sites in the N-MWCNTs nanocomposite. X-ray photoelectron spectroscopy (XPS) reveals peaks at 399.38, 400.49, and 402.05 eV, attributed to pyridinic-N, aromatic amide-N, and protonated amine groups, respectively. N₂ adsorption-desorption studies shows a high Brunauer-Emmett-Teller (BET) surface area for N-MWCNTs (119.22 m2/g) compared to MWCNTs (74.94 m2/g). Linear sweep voltammetry (LSV) profiles demonstrate enhanced activity of N-MWCNTs for both HER and SCB oxidation at an ultralow potential of E = −0.55 V vs RHE at 10 mA/cm2, with a lower Tafel slope of 108 mV.dec−1. Moreover, the electrochemical sensing studies indicates on N-MWCNTs were demonstrating an efficient electron transfer to SCB with the lower detection limit of 0.004 μmol. This work provides carbon-based metal-free electrocatalysts for energy harvesting and environmental management.

Mongrel synthesis of tin (IV) based 3-aminopyridine with hydrogen halides: Structural, optical, thermal analysis, DFT, Hirshfeld surface analysis and antibacterial investigations

The novel organic-inorganic hybrid materials (C5H7N4)2 [SnCl6] 2- (1) and (C5H7N4)2 [SnBr6]2-(2) have been synthesized and characterized by single-crystal X-ray diffraction at room temperature. Both compounds demonstrate the crystal system was triclinic with Pī space group. Hirshfeld surface analysis investigate the intermolecular interactions and crystal packing derived by single-crystal XRD data reveals the closer contacts associated with strong interactions. Infrared spectrum of both compounds shows the NH stretching band at 3396 cm−1 which indicates a protonated amine group. The product crystals optical characteristics were inspected using UV–visible and photoluminescence spectroscopy. The thermal characteristics were evaluated simultaneously using thermogravimetric (TG) and differential thermal analysis. Tin formal oxidation state was determined as +4 through bond valence sum calculations and CSM shows the ideal octahedral geometry of the anions. DFT calculations utilizing the B3LYP method with the LanL2DZ basis set provide optimized geometries and molecular electrostatic potential maps. We explored the energy difference between (HOMO) and (LUMO) orbitals to understand molecular electrical transport capabilities. The biological activity of the investigated compounds are examined against pathogens which indicates efficacy against bacterial strains.

Cryogenic Ion Vibrational Spectroscopy of Protonated Valine: Messenger Tag Effects.

We report the infrared photodissociation spectrum of tagged protonated valine in the range 1000-1900 cm-1, prepared in a cryogenic ion trap. Comparison of experimental results with calculated infrared spectra based on density functional theory shows that the hydroxyl group of the carboxylic acid functionality and the protonated amine group adopt a trans configuration. Nitrogen and methane molecules were used as messenger tags with optimal tagging temperatures of 30 K for N2 and 60 K for CH4. While the calculated infrared spectra of the tagged ion suggest only a weak influence of the messenger tag on the frequency positions of ValH+, the measured intensities for N2-tagged ValH+ appear strongly suppressed for all but the highest frequency feature at 1773 cm-1. We trace this behavior to the binding energy of the N2 tag, which is significantly higher than that of CH4, based on density functional and coupled cluster calculations and rate estimates for photoinduced unimolecular dissociation from statistical theory.

Inhibition of the polymer grafted with dopamine derivatives on hydration and swelling of clay

Swelling of clay minerals is one of the main factors restricting the efficient exploration and development of shale oil and gas. To solve this issue, the free radical induction method was employed to synthesize a polymer grafted with dopamine derivatives, P(AM-DA). This study aimed to evaluate the inhibitory properties of P(AM-DA) on the hydration and swelling of clay and analyze its mechanism. Firstly, P(AM-DA) was characterized by FTIR, HNMR, and TGA. Subsequently, anti-swelling, anti-disintegration, and immersion tests were conducted to evaluate its inhibitory properties. Then, the inhibitory mechanism was further elucidated through Zeta potential tests, particle size analysis, XRD tests, and SEM analysis. Finally, the properties of P(AM-DA) on mud rheology and fluid loss were evaluated. The experimental results showed that the dopamine derivatives were successfully grafted onto the polymer's side chains. Additionally, the result of TGA demonstrated the polymer's good thermal stability below 200℃. P(AM-DA) showed a superior inhibitory effect, and the swelling rate of cores was much lower than that of KCl and polyetheramine. Despite the clay mineral content of shale cuttings being as high as 51.1 %, the anti-disintegration rate could be increased by 66.45 %. The Na-BT core retained its shape and structural integrity after 72-hours immersion, and it could support a weight of 200 g. Regarding the inhibitory mechanism, P(AM-DA) could adsorb onto the surface of clay particles through hydrogen bonding and electrostatic interaction, which reduced the dispersion of clay particles. The protonated amine groups could neutralize the electronegativity of the clay particles, reducing the electrostatic repulsion between the layers. Besides, P(AM-DA) exhibited a series of special behaviors, such as adsorption on the core surface to form a homogeneous layer and insertion into the crystal layer of clay. Both of these behaviors could decrease the passage of water molecules, and the intercalation behavior could also reduce and stabilize the interlayer spacing. In addition, P(AM-DA) could dramatically increase the viscosity of the fluid at higher concentrations and unexpectedly reduce fluid loss. In conclusion, P(AM-DA) showed considerable promise in inhibiting hydration and swelling of clay.

A Single Amino Acid Able to Promote High-Temperature Ring-Opening Polymerization by Dual Activation.

Amino acids are indispensable compounds in the body, performing several biological processes that enable proper functioning. In this work, it is demonstrated that a single amino acid, taurine, is also able to promote the ring-opening polymerization (ROP) of several cyclic monomers under industrially relevant conditions. It is shown that the unique zwitterionic structure of taurine, where the negatively charged sulfonic acid group and the protonated amine group are separated by two methylene groups, not only provides high thermal stability but also leads to a dual activation mechanism, which is corroborated by quantum mechanical calculations. This unique mechanism allows for the synthesis of polylactide of up to 50kDa in bulk at 180 °C with good end-group fidelity using a highly abundant catalyst. Furthermore, cytotoxicity tests confirm that PLLA synthesized with taurine is non-toxic. Moreover, it is demonstrated that the presence of taurine does not have any detrimental effect on the thermal stability of polylactide, and therefore polymers can be used directly without any post-polymerization purification. It is believed that the demonstration that a simple structure composed of a single amino acid can promote polymerization can bring a paradigm shift in the preparation of polymers.

Surface adsorption of L-phenylalanine on silver colloidal nanoparticles investigated by surface-enhanced Raman spectroscopy

L-phenylalanine (L-Phe) is one of three aromatic amino acids frequently used in numerous vibrational applications, including surface-enhanced Raman spectroscopy (SERS). Despite the wide applications, the spectral analyses and vibrational assignments of the Raman spectra of L-Phe based on surface adsorption on metallic nanosurfaces are limited. In this work, we report pH-dependent SERS of L-Phe adsorbed on borohydride-reduced silver colloidal nanoparticles, where the spectral changes upon protonation of amine group are understood as the modification in the surface adsorption via the carboxylate and amino group. In-plane and out-of-plane ring stretching and aromatic ν(CH) modes appear sensitive to the surface orientation of the phenyl ring, and the peripheral vibrational modes, including the stretching and bending of carboxylate and amine groups, are crucial to understanding the detailed surface adsorption mechanisms of L-Phe in anionic and zwitterionic forms depending on the solution pH. The pH-dependent intensity changes of the major ring stretching modes show that the surface pKa of L-Phe decreases to ∼6 from the bulk value of 9.13.

Exploring the effect of a pendent amine group poised over the secondary coordination sphere of a cobalt complex on the electrocatalytic hydrogen evolution reaction.

A CoIII complex (2) of a bispyridine-dioxime ligand (H2LNMe2) containing a tertiary amine group in the proximity of the Co center is synthesized and characterized. One of the oxime protons of the ligand is deprotonated, and the amine group remains protonated in the solid-state structure of the CoII complex (2a). The acid-base properties of 2 showed pKa values of 5.9, 8.4, and 9.6, which are assigned to the dissociation of two consecutive oxime protons and amine protons, respectively. The electrocatalytic proton reduction of 2 was investigated in an aqueous phosphate buffer solution (PBS), revealing a catalytic hydrogen evolution reaction (HER) at an Ecat/2 of -1.01 V vs. the SHE, with an overpotential of 673 mV and a kobs value of 2.6 × 103 s-1 at pH 7. For comparison, the HER of the Co complex (1) lacking the tert-amine group at the secondary sphere was investigated in PBS, which showed a kobs of 1.3 × 103 s-1 and an overpotential of 577 mV. At pH 4, however, 2 revealed a ∼3 times higher kobs value than 1, which suggests that the protonated amine group likely works as a proton relay site. Notably, no significant change in the reaction rate was observed at different pH values for 1, implying that oxime protons may not be involved in the intramolecular proton-coupled electron transfer reaction in the HER. The kobs values for Co complexes at pH 7.0 are significantly higher than those of the [Co(dmgH)2(pyridine)(Cl)] complex, implying that the primary coordination sphere around 1 or 2 enhances the HER and offers better catalyst stability in acidic buffer solutions.

Synthesis and Characterization of Iodinated Chitosan Nanoparticles and Their Effects on Cancer Cells.

The high degree of chemical modification of the chitosan chains due to protonated amine groups allows them to react with many negatively charged surfaces as anionic polymers and cell membranes, resulting in an attractive material for medical and pharmaceutics applications. Incorporating ionic iodine (I- and IO3 -) on chitosan chains is a direct way to successfully obtain chitosan-iodine nanoparticles (CSNPs-I and CSNPs-IO3) through ionic gelation. The nanoparticles (NPs) present a hemispherical morphology with sizes around 30-70 nm for CSNPs-I and CSNPs-IO3, similar to chitosan NPs, in accordance with SEM and DLS techniques. The XRD characterization did not show noticeable differences in the crystallinity index (CI) for CSNPs and CSNPs-I, 48.4 and 49.3%, respectively, but for CSNPs-IO3, the CI decreased to 43.85%. The cytotoxic effects on human tumor cells of chitosan and iodine-modified chitosan nanoparticles (CSNPs-I and CSNPs-IO3) were evaluated for 24 h in a range from 0.15 mg/mL to 0.95 mg/mL concentrations, where CSNPs-IO3 presented the lower viability for lung cancer A549, followed by cervical cancer HeLa cell and finally breast cancer MDA-MB-231, with a weight content of iodate ion in a range of 8.7 to 15 μg. This work presents the possibility of exploring chitosan-iodine NPs in medical applications.

Regenerable planting of multifunctional amine: Regeneration-enhanced antifouling/antiscaling properties and performance of thin film composite nanofiltration membrane

The problems of poly(piperazineamide)-based thin film composite (TFC) nanofiltration (NF) membrane are the fouling, scaling and poor separation performance of uncharged organics and heavy metal ions. Permanent surface modification lowers the fouling/scaling problems. However, these problems persist as the separation progresses. We address these issues by the on-demand regenerable planting of polyethyleneimine (PEI) into the polyamide (PA) layer of TFC NF membrane. The regenerable planting is based on the electrostatic interaction among the protonated amine groups of low molecular weight PEI and ionized carboxylic acid groups situated at the relatively inner sites (low dielectric constant) of the PA network. The incorporated PEI chains are stable at the pH range of 3–9. The PEI incorporated membrane exhibits significantly enhanced antifouling/antiscaling property, rejection of heavy metal ions (98–99%) and bisphenol A (BPA, 95%) without much negatively affecting the bivalent anion rejection (Na2SO4, 97.5%) and water permeance (11 L m−2 h−1 bar−1) as compared to the pristine and commercial membranes (55–82%, 50–76% and 98–99% rejections of heavy metal ions, BPA and Na2SO4). Advantageously, PEI chains are removable at pH ≤ 2 or pH ≥ 9.5 without affecting the main PA layer. The multiple removal and re-generation of the membrane have been achieved. The flux recovery of the membrane after antifouling/antiscaling tests significantly improved upon intentional removal and reincorporation of PEI. Inherent properties of the modified membrane channels couple with the on-demand regenerable ability show immense promises of the membrane in the separation applications.

Poly(PEI‐catechol‐tetraethylenepentamine) was prepared by “one‐pot method” for removing Reactive Red 195

AbstractWastewater containing dyes is frequently discharged by industrial processes and needs separation and recycling. To solve this problem, it is important to research and develop environmentally friendly, efficient adsorbent materials for pollutant separation and recovery. In this study, a poly(PEI‐catechol‐tetraethylenepentamine) (PPCT) adsorbent was synthesized using a simple catecholamine reaction. This adsorbent exhibited high adsorption capacity and excellent removal efficiency for Reactive Red 195 (RR‐195) in wastewater. The material was characterized using SEM, FT‐IR, TGA, EA, and XPS. Its performance was optimized by varying the type of polyethyleneimine and the amount added during the preparation process. The effects of temperature, pH, contact time, and salt concentration on the adsorption were systematically investigated. Additionally, the experimental data showed consistency with both the Langmuir and pseudo‐second‐order kinetic models, simultaneously. The maximum adsorption capacity can reach 1754 mg g−1 at 303 K, with a retention rate of 86.6% after two cycles. The removal rate exceeds 98% at a concentration of 400 mg g−1 or lower. Additionally, the protonated amine group in PPCT carries a positive charge under acidic conditions, enabling selective adsorption of the anionic dye RR‐195. Consequently, PPCT exhibits an excellent adsorption effect on RR‐195 and holds promising applications in pollutant removal.

Enhanced synergistic removal of Cu(II) and Cr(VI) with multifunctional biomass hydrogel from strong-acid media

Simultaneous recovery of heavy metal ions (HMIs) such as Cu(II) and Cr(VI) from strong-acid media was a great challenge due to the inhibition of protons. Herein, a novel biomass hydrogel (CMC/PEI-PD) containing various groups (bis-picolylamine, amino, and hydroxyl groups) was newly prepared by a facile two-step process. The static experiments relating pH, kinetics and isothermal co-adsorption confirmed the synergistic effect towards Cu(II) and Cr(VI) consistently. Specifically, the adsorption capacities of Cu(II) and Cr(VI) at pH 2.0 increased by 23.73% and 40.18% in comparison with the single systems. Moreover, coexistence of inorganic anions and cations could further increase the adsorption of Cu(II) and Cr(VI) by 59.90% and 43.39%, respectively. At the same time, the adsorption and desorption ratios for both HMIs remained stable. The superior performance came from the two dominant mechanisms of co-removal. On the one hand, Cu(II) chelated by bis-picolylamine group attracted Cr(VI) in the form of cation bridge, thus promoting Cr(VI) adsorption. On the other hand, the protonated amine group attracted Cr(VI) by electrostatic interaction and weakened the inter-cationic repulsion by electrostatic shielding, thus promoting Cu(II) adsorption. In addition, the dynamic column experiment towards simulated acidic electroplating wastewater involving Cu(II)–Cr(VI)–Ni(II) certified the high efficiency and feasibility of the co-removal. Therefore, CMC/PEI-PD owned great potential in the separation of typical HMIs even directly from strong-acid media.

Interfacial polycondensation of polyamides studied at the electrified liquid-liquid interface

In this work, we present the possibility to electrochemically assist and study the interfacial polycondensation derived from the reactions between 1,6-diaminohexane or p-phenylenediamine (used as the diamine initially present in the aqueous phase) and acyl chlorides in a form of 1,3,5-benzenetricarbonyl trichloride, terephthaloyl chloride or adipoyl chloride (present in the organic phase – 1,2-dichloroethane solution). Polyamides are synthesized at the polarized liquid – liquid interfaces (or the interface between two immiscible electrolyte solutions – ITIES) as a consequence of the transfer of partly protonated diamines from the aqueous to the organic phase. In this respect, we have defined the aqueous phase pH assuring the availability of amine groups (-NH2) for the reaction with the acyl chloride and protonated amine groups (-NH3+) defining the electrochemical interfacial activity of chosen compounds. The possibility to electrochemically assist the interfacial formation of polyamides was first tested using the macroscopic ITIES. Formed polyamides were collected and analysed using scanning electron microscopy, energy dispersive x-ray spectroscopy and Raman spectroscopy. Next, we have employed the microscopic ITIES (microITIES) based system formed using fused silica microcapillaries. Cyclic voltammetry was employed for the polyamide modified microITIES assessment (evolution of molecular sieving properties using a model ion - tetramethylammonium cation).

Dendrimer functionalized spinel ferrite for robust sorption of precious metals from strongly acidic medium

The separation of noble metal ions from strongly acidic solutions is considered to be a challenging task due to the significantly low pH of these solutions. Spinel ferrites possess unique physicochemical properties, such as excellent magnetic properties, high specific surface area, high chemical stability, active surface sites, and easy modification or functionalization, making them suitable for various applications. In this study, we have introduced a facile method for synthesizing polyamidoamine (PAMAM) dendrimer-functionalized spinel ferrite (DFSF) with a particle size of approximately 10 nm. The prepared DFSF materials have investigated its ability to adsorb Pt(IV) and Pd(II) anions (PtCl62− and PdCl42−) from strongly acidic solutions. The results indicate that the adsorption kinetics and isotherm studies of synthesized materials have a rapid and high adsorption capacity for Pt(IV) and Pd(II) with simple solid-liquid separation. The data analysis suggests an anion exchange interaction between the adsorbate and the adsorbent, specifically the electrostatic interaction between the protonated amine group (–NH3+) and the noble metal anions (PtCl62–and PdCl42−). The Pseudo second-order rate model fitting suggests that the adsorption of noble metals by DFSF is a function of valence. The excellent superparamagnetic properties (0.346 emu g−1) of DFSF make it a promising candidate for large-scale applications, as it exhibited good reusability with a short recovery time (25 s) and high recovery efficiency through the adsorption-reduction-precipitation route. This study suggests that DFSF can be a potential sorbent for noble metal ions in various applications.

PEI-modified chitosan/activated carbon composites for Cu(II) removal from simulated pyrophosphate plating rinsing wastewater

It is a challenging task to remove heavy metal ions efficiently from the wastewater containing high concentrations of complexants. In this work, a novel PEI-modified chitosan/activated carbon composite adsorbent (PCA) was prepared and applied to the removal of Cu(II) from pyrophosphate plating rinsing wastewater. The main species of Cu(II) in the pyrophosphate wastewater was [Cu(HP2O7)2]4− or [Cu(P2O7)2]6−, which were denoted as [Cu(II)-PP] anions. The maximum adsorption capacity of PCA for Cu(II) reached 1.41 mmol g−1 under the condition of pH = 8 and molar ratio of pyrophosphate to Cu(II) = 4:1. The adsorption kinetic behavior of Cu(II) on PCA followed the Elovich model best and PCA attained adsorption equilibrium within 36 h. The thermodynamic studies showed that the adsorption process of Cu(II) by PCA was endothermic and spontaneous. The PCA fixed bed column was used to remove Cu(II) from simulated pyrophosphate plating rinsing wastewater. After three consecutive adsorption-desorption cycles, the adsorption performance, hydraulic conductivity, and mechanical stability of PCA column did not decrease. The FTIR and XPS analysis results indicated that [Cu(II)-PP] anions can be adsorbed on PCA by electrostatic attraction with protonated amine groups or coordination with the amine groups of PCA via ligand substitution.

Increasing Surface Functionalities of FeCl3-Modified Reed Waste Biochar for Enhanced Nitrate Adsorption Property

Ferric chloride (FeCl3) modified reed straw-based biochar was synthesized to remove nitrate from aqueous solutions and achieve waste recycling. The adsorption of nitrate onto Fe-RBC-600 adsorbents could be described by the pseudo-second-order kinetic model and fitted to Langmuir adsorption, and the maximum adsorption capacity predicted using the Langmuir model was 272.024 mg g−1. The adsorbent characterization indicated that a high temperature of 600 °C and an oxygen-poor environment could develop a hydrophobic surface and O-containing functional groups on the biochar, which provided more binding sites for Fe3+/Fe2+ attachment and increased the surface functionality of Fe-RBC-600 with iron oxide formation. The increasing surface functionality successfully enhanced the nitrate adsorption property. The mechanism of nitrate adsorption was mainly attributed to the physical adsorption onto the positive surface and sequential chemical reduction by Fe2+, and the electrostatic adsorption by protonated amine groups.

All-natural water-resistant paper coated by chitosan nanowhiskers through hydrophilic-to-hydrophobic self-assembly

Although chitosan-coated hydrostable papers are promising alternatives to non-degradable plastic-coated papers, an acidic chitosan solution is not eco-friendly. Therefore, we developed a non-acidic aqueous coating technique for preparing all-natural water-resistant papers using chitosan nanowhiskers (CSWs). As the CSWs disperse in water after synthesis, they form a hydrophobic layer on the paper after the coating process owing to the hydrophilic-to-hydrophobic self-assembly. Quantum simulations reveal that the repulsion between protonated amine groups contributes to water dispersibility; however, their interfibrillar interaction after coating is hardly dissociated by water. Together with soybean oil, the CSW- and oil-coated papers (C/O-papers) exhibit significantly higher water contact angles (95.8°) and absorption (6.0%) than control paper (21.9° and 91.9%, respectively). Moreover, the C/O-papers had a 16.0- and 9.1-fold higher mechanical modulus and strength (1498.5 and 31.0 MPa, respectively) than control paper (93.8 and 3.4 MPa, respectively) under wet conditions. Therefore, bio-renewable water-resistant paper has great potential for preparing disposable materials.

Liposome Formulations for the Strategic Delivery of PARP1 Inhibitors: Development and Optimization.

The development of a lipid nano-delivery system was attempted for three specific poly (ADP-ribose) polymerase 1 (PARP1) inhibitors: Veliparib, Rucaparib, and Niraparib. Simple lipid and dual lipid formulations with 1,2-dipalmitoyl-sn-glycero-3-phospho-rac-(1'-glycerol) sodium salt (DPPG) and 1,2-dipalmitoyl-sn-glycero-3-phosphocoline (DPPC) were developed and tested following the thin-film method. DPPG-encapsulating inhibitors presented the best fit in terms of encapsulation efficiency (>40%, translates into concentrations as high as 100 µM), zeta potential values (below -30 mV), and population distribution (single population profile). The particle size of the main population of interest was ~130 nm in diameter. Kinetic release studies showed that DPPG-encapsulating PARP1 inhibitors present slower drug release rates than liposome control samples, and complex drug release mechanisms were identified. DPPG + Veliparib/Niraparib presented a combination of diffusion-controlled and non-Fickian diffusion, while anomalous and super case II transport was verified for DPPG + Rucaparib. Spectroscopic analysis revealed that PARP1 inhibitors interact with the DPPG lipid membrane, promoting membrane water displacement from hydration centers. A preferential membrane interaction with lipid carbonyl groups was observed through hydrogen bonding, where the inhibitors' protonated amine groups may be the major players in the PARP1 inhibitor encapsulation mode.