Fouling causes huge economic losses for industrial process. In this work, experimental and molecular dynamics simulation approaches were used to carefully examine the scale inhibitory effects of ...carboxymethyl dextran (CMD) on the nucleation and crystallization process of calcium carbonate. The findings of the experiment demonstrated that CMD could significantly inhibit calcium carbonate's crystallization and nucleation processes. Moreover, an increase in the CMD concentration prolonged the induction period of calcium carbonate nucleation, and led to an increase in the critical conductivity value, inhibition effect on the nucleation process, and scale inhibition efficiency. The simulation results demonstrated the presence of strong interactions between the calcium ions in solution and the carboxyl groups of CMD. The probability and strength of calcium and carbonate ions adsorbing to the solution's surface decreased as the CMD concentration rose. Adsorption probability and strength of calcium and carbonate ions in the solution declined as CMD concentration rose, tightly agglomerated calcium carbonate gradually dispersed into small clusters and ions, and scale inhibition effectiveness improved. The experimental results were found to be in good agreement with the simulation results.
Display omitted
•Experimental methods combined with molecular dynamics simulations.•CMD inhibited the nucleation and crystallization process of calcium carbonate.•CMD decreased the probability of collision aggregation of calcium carbonate particles.•CMD transformed calcium carbonate from a tightly-agglomerated state to smaller clusters and ions.•The scale inhibition efficiency increased with the concentration of CMD increased.
The scale inhibition mechanism of carboxymethyl dextran (CMD), a new green scale inhibitor, was studied via quantum mechanical calculations and molecular dynamics (MD) simulations. Specifically, the ...interactions between the functional groups of CMD and calcite (104), (110), and (1–10) surfaces in aqueous solution were modelled at different degrees of polymerization (DP) of CMD (2, 4, 6, 8, and 10, respectively). The adsorption configuration, radial distribution function, deformation energy, binding energy, and relative concentration distribution of water molecules near the surface of calcite were calculated. The results showed that the carboxyl functional groups in CMD were strongly electronegative and able to form strong chemisorption bonds with calcium ions on the calcite surface. This can change the regular arrangement of the surface and prevent the combination of carbonate particles and calcium ions to form calcite scale. Furthermore, as the DP increased, the binding energy and the peak value of the radial distribution function increased, indicating an increase in the probability and strength of adsorption of CMD on the calcite surface, which can further enhance the scale inhibition efficiency.
Display omitted
•Quantum mechanics combined with molecular dynamics simulation was used to study the scale inhibition mechanism of CMD.•The carboxyl functional group was the most electronegative functional group in CMD.•Enhanced chemical bonding occurred between the carboxyl functional groups and calcium ions.•The scale inhibition efficiency increased with the degrees of polymerization of CMD increased.•The scale inhibition efficiency of CMD on surfaces were in the order of calcite (104) < calcite (110) < calcite (1−10).
Chitosan has emerged as a promising polysaccharide for gene/siRNA delivery. However, additional works will be required to modify chitosan nanoparticles. In the present study, chitosan nanoparticles ...were well modified to introduce anti-HIV siRNA into two mammalian cell lines, macrophage RAW 264.7 and HEK293. We first generated two stable cell lines expressing HIV-1 Tat, and then designed and generated an efficient anti-tat siRNA. The nanoparticles were prepared by using different concentrations of chitosan, polyethylenimine (PEI) and carboxymethyl dextran (CMD) in various formulations and then their physicochemical and biological properties were investigated. The results demonstrated that the combination of chitosan with both CMD and PEI significantly improved both cell viability and siRNA delivery. The modified chitosan nanoparticles (ChNPs) at the N:P ratio of 50 were approximately uniform spheres with sizes ranging from 100 to 150 nm and a positive zeta potential of about +22 mV. In both cell types, the nanoparticles noticeably increased siRNA delivery efficiency with no significant cytotoxicity or apoptosis-inducing effects compared to the control cells. In addition, the nanoparticles significantly reduced the RNA and protein expression of HIV-1 tat in both stable cells. These data show that the nanoparticle formulation could potentially be used in gene therapy, especially against HIV infection.
Display omitted
•Generation of two stable cell lines, macrophage RAW 264.7 and HEK293, expressing HIV-1 Tat.•Designing specific siRNAs targeting HIV-1 tat gene.•Synthesis of chitosan nanoparticles and modification by polyethylenimine (PEI) and carboxymethyl dextran (CMD).•High cell viability and siRNA delivery efficiency by adjusting the molar ratio of precursors (siRNA, chitosan, CMD and PEI).•Effectively suppression of HIV-1 Tat by the siRNA-loaded nanoparticles in stable cells.
l-asparaginase is a chemotherapy agent in the treatment of childhood leukemia. l-asparaginase has several side effects and a short blood half-life in patients. Chemical modification of l-asparaginase ...can decrease its side effects and improve its pharmacokinetic properties. The aim of this project was twofold: to chemically modify l-asparaginase with carboxymethyl dextran via carbodiimide cross linker, and to evaluate and compare the biochemical and structural properties of the native and modified enzymes. Chemical modification was done at 25 °C, in 0.1 M phosphate buffer, pH 7.2, and in the presence of N-hydroxysuccinimide and carbodiimide. Electrophoresis and free amino groups determination confirmed the chemical modification. Biochemical studies showed that the chemical modification could result in higher specific activity and stability of the modified enzyme. Structural studies further confirmed the chemical modification and revealed conformational changes in the modified enzyme. Taken together, the results showed that chemical modification with carboxymethyl dextran brings about improvement of biochemical properties through several changes in the structural attributes of l-asparaginase and might enhance its applicability in the treatment of childhood leukemia.
Display omitted
•L-asparaginase protein has several lysine residues on its surface.•Carboxyl groups of carboxymethyl dextran can connect to Ɛ-amino group of lysines via carbodiimide crosslinker.•Attachment of carbohydrate on enzyme surface can induce conformational changes in the modified enzyme.•Enzymatic conformational changes can result in kinetic parameters and stability changes in the modified l-asparaginase.
Bioreducible carboxymethyl dextran (CMD) derivatives are synthesized by the chemical modification of CMD with lithocholic acid (LCA) through a disulfide linkage. The hydrophobic nature of LCA allows ...the conjugates (CMD‐SS‐LCAs) to form self‐assembled nanoparticles in aqueous conditions. Depending on the degree of LCA substitution, the particle diameters range from 163 to 242 nm. Doxorubicin (DOX), chosen as a model anticancer drug, is effectively encapsulated into the nanoparticles with high loading efficiency (>70%). In vitro optical imaging tests reveal that the fluorescence signal of DOX quenched in the bioreducible nanoparticles is highly recovered in the presence of glutathione (GSH), a tripeptide capable of reducing disulfide bonds in the intracellular compartments. Bioreducible nanoparticles rapidly release DOX when they are incubated with 10 mm GSH, whereas the drug release is greatly retarded in physiological buffer (pH 7.4). DOX‐loaded bioreducible nanoparticles exhibit higher toxicity to SCC7 cancer cells than DOX‐loaded nanoparticles without the disulfide bond. Confocal laser scanning microscopy observation demonstrate that bioreducible nanoparticles can effectively deliver DOX into the nuclei of SCC7 cells. In vivo biodistribution study indicates that Cy5.5‐labeled CMD‐SS‐LCAs selectively accumulate at tumor sites after systemic administration into tumor‐bearing mice. Notably, DOX‐loaded bioreducible nanoparticles exhibit higher antitumor efficacy than reduction‐insensitive control nanoparticles. Overall, it is evident that bioreducible CMD‐SS‐LCA nanoparticles are useful as a drug carrier for cancer therapy.
Bioreducible nanoparticles bearing the disulfide bond are developed for the site‐specific delivery of poorly water‐soluble anticancer drugs at the tumor microenvironment. The nanoparticles are composed of hydrophilic carboxymethyl dextran and hydrophobic bile acid with an intervening disulfide bond. The hydrophilic shells of nanoparticles allow their prolonged circulation in the bloodstream, whereas the bioreducible disulfide bonds trigger the drug release inside the tumor cells after internalization of nanoparticles.
Paclitaxel (PTX) is an essential anticancer drug from the biopharmaceutical classification system (BCS) class IV. Unfortunately, PTX has some drawbacks including low solubility, cell toxicity, ...adverse cell reaction, etc. Therefore, folic acid (FA) tailored carboxymethyl-dextran (CMD), and bovine serum albumin (BSA) mediated nanoconjugates of paclitaxel (PTX) (FA-CMD-BSA-PTX) were designed. At first, esterification reaction between FA and CMD resulted in FA-CMD conjugate whereas FA-CMD-BSA conjugate was synthesized via the Maillard reaction. Finally, FA-CMD-BSA conjugates of PTX were achieved via hydrophobic interaction and gelation of BSA. Herein, heating offers the gelation of BSA that furnishes the cross-linking wherein PTX gets fixed inside BSA. Thermogram of FA-CMD-BSA-PTX showed the absence of PTX peak that concluding PTX has been molecularly dispersed in polymer matrix and entrapment inside polymeric conjugate. As an effect, surface decorated FA-CMD-BSA-PTX showed low hemolytic toxicity over free PTX. Cytotoxicity assay on A549 human lung cancer cells shows cell viability decreased from 60 % to 10 % with increasing concentration from 1 to 5 μg/mL. In conclusion, CMD facilitates the circulation time of PTX and BSA acts as a carrier to target tumor locations effectively. The nano-conjugate formulation significantly reduces toxicity and can be used for the treatment of lung cancer.
Display omitted
•Non-small cell lung cancer accounts for 85 % of lung cancer.•Folic acid-tailored carboxymethyl-dextran and bovine serum albumin-based nanoconjugates of paclitaxel were designed.•Folic acid on the nanoconjugates surface enables the conjugate to target folate receptor-over expressed in tumor.•Anticipated folic acid-tailored paclitaxel nanoconjugates improved the anticancer activity in human lung cancer cells.•The design of surface-tailored carboxymethyl dextran-protein-based nanoconjugates will provide a new alternative for paclitaxel delivery.
•Synthesis of carboxymethyl dextran-coated magnetoliposomes.•Good stability in serum and high drug loading ability for doxorubicin.•Enhanced drug release under low-frequency alternating magnetic ...field.•High relaxivity ratio of r2 to r1 as T2-weighted contrast agent in MR imaging.•A potential carrier for targeting diagnostic-therapy for cancers.
The aim of this work was to construct carboxymethyl dextran (CMD)-coated magnetoliposomes (MLs), another stealth MLs alternative to PEGylated MLs, for theranostic application. Particularly, the on-demand release of CMD-MLs under low-frequency alternating magnetic field (LF-AMF) was studied. We found that as-prepared MLs exhibited good stability and high drug loading ability for doxorubicin (DOX). Cytotoxicity assay against human neuroblastoma SH-SY5Y cells showed that the DOX-loaded CMD-MLs were less toxic than free DOX due to the sustained release of DOX. However, the release of DOX-loaded CMD-MLs was enhanced by low-frequency alternating magnetic field without hyperthermia generation. The MLs also acted as an efficient T2-weighted contrast agent during in vitro MRI measurements. The above results provide useful information on in vivo diagnostic/therapeutic efficacy of DOX-loaded CMD-MLs for some cancers, such as brain cancers.
The increased mortality rates associated with colorectal cancer highlight the pressing need for improving treatment approaches. While capsaicin (CAP) has shown promising anticancer activity, its ...efficacy is hampered due to low solubility, rapid metabolism, suboptimal bioavailability, and a short half-life. Therefore, this study aimed to prepare a lactoferrin-functionalized carboxymethyl dextran-coated egg albumin nanoconjugate (LF-CMD@CAP-EGA-NCs) for the targeted CAP delivery to enhance its potential for colorectal cancer therapy. Briefly, LF-CMD was synthesized through an esterification reaction involving LF as a receptor and CMD as a shell. Concurrently, CAP was incorporated into an EGA carrier using gelation and hydrophobic interactions. The subsequent production of LF-CMD@CAP-EGA-NCs was achieved through the Maillard reaction. Spectral characterizations confirmed the successful synthesis of smooth and spherical-shaped LF-CMD@CAP-EGA-NCs using LF-CMD and EGA-CAP nanoparticles, with high entrapment efficiency and satisfactory drug content. Furthermore, LF-CMD@CAP-EGA-NCs demonstrated a sustained release of CAP (76.52 ± 1.01 % in 24 h, R
= 0.9966) in pH 5.8 buffer with anomalous transport (n = 0.68) owing to the shell of the CMD and EGA matrix. The nanoconjugate exhibited enhanced cytotoxicity in HCT116 and LoVo cell lines, which is attributed to the overexpression of LF receptors in colorectal HCT116 cells. Additionally, LF-CMD@CAP-EGA-NCs demonstrated excellent biocompatibility, as observed in the FHC-CRL-1831 cell line. In conclusion, LF-CMD@CAP-EGA-NCs can be considered as a promising approach for targeted delivery of CAP and other anticancer agents in colorectal cancer treatment.
Gene therapy, including small interfering RNA (siRNA) technology, is one of the leading strategies that help to improve the outcomes of the current therapeutic systems against HIV‐1 infection. The ...successful therapeutic application of siRNAs requires their safe and efficient delivery to specific cells. Here, we introduce a superparamagnetic iron oxide nanoparticle (SPION) for delivering siRNA against HIV‐1 nef (anti‐nef siRNA) into two cell lines, HEK293 and macrophage RAW 264.7. SPIONs were coated with trimethyl chitosan (TMC), and thereafter, different concentrations of SPION–TMC were coated with different ratios of a carboxymethyl dextran (CMD) to modify the physicochemical properties and improve the biological properties of the nanocarriers. The nanoparticles exhibited a spherical shape with an average size of 112 nm. The obtained results showed that the designed delivery route enhanced the uptake of siRNA into both HEK293 and RAW 264.7 cells compared with control groups. Moreover, CMD–TMC–SPIONs containing anti‐nef siRNA significantly reduced the expression of HIV‐1 nef in HEK293 stable cells. The modified siRNA‐loaded SPIONs also displayed no toxicity or apoptosis‐inducing effects on the cells. The CMD–TMC–SPIONs are suggested as potential nanocarriers for siRNA delivery in gene therapy of HIV‐1 infection.
In this study, we attempted to design an effective siRNA for silencing HIV‐1 nef gene and provided an efficient and nontoxic carrier system (CMD–TMC–SPIONs) for delivering siRNAs into two mammalian cell lines, HEK293 and macrophage RAW 264.7.
