Molecular dynamics simulation study of doxorubicin adsorption on functionalized carbon nanotubes with folic acid and tryptophan.
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ABSTRACT:
SUBMITTER: Arabian T
PROVIDER: S-EPMC8688492 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:In this work, we developed a novel active targeting and pH-responsive system for delivering the drug doxorubicin (DOX) to tumor sites using folic acid (FA)-modified multiwalled carbon nanotubes (MWCNTs). Acid-treated MWCNTs with carboxyl groups were first covalently conjugated with polyethyleneimine (PEI). Subsequent sequential modification with FA (via a polyethylene glycol spacer), fluorescein isothiocyanate (FI), and acetic anhydride/triethylamine resulted in multifunctional FA-bound MWCNT (MWCNT-PEI.Ac-FI-PEG-FA) nanomaterials that possessed exceptional colloidal stability and good biocompatibility in a given concentration range. The FA-bound MWCNTs were characterized using various techniques and exhibited a high drug loading and an encapsulation efficiency as high as 70.4%. DOX/MWCNT-PEI.Ac-FI-PEG-FA nanocomplexes (DOX/MWCNT NCs) exhibited pH-responsive release in acidic environments. Importantly, the DOX/MWCNT NCs targeted tumor cells overexpressing FA receptors (FARs) and effectively inhibited their growth. In vivo anticancer experiments demonstrated that DOX/MWCNT NCs not only enhanced the suppression of tumor growth but also decreased the side effects of free DOX. The developed FA-modified MWCNTs with an unconventionally high DOX loading boosted in vivo anti-tumor efficacy, and the lower systemic toxicity may be utilized for tumor therapy upon clinical translation.
| S-EPMC6201812 | biostudies-literature
Project description:By considering the importance of water and its purity, herein, a powerful adsorbent has been developed for the adsorption of two toxic contaminants that commonly exist in water, viz., divalent mercury and hexavalent chromium. The efficient adsorbent, CNTs-PLA-Pd, was prepared by covalent grafting polylactic acid to carbon nanotubes and subsequent deposition of palladium nanoparticles. The CNTs-PLA-Pd could adsorb Hg(II), and Cr(VI) entirely exists in water. The adsorption rate for Hg(II) and Cr(VI) was rapid at initial stage, followed by gradual decrease, and attained the equilibrium. The Hg(II) and Cr(VI) adsorption was perceived within 50 min and 80 min, respectively with CNTs-PLA-Pd,. Further, experimental data for Hg(II) and Cr(VI) adsorption was analyzed, and kinetic parameters were estimated using pseudo-first and second-order models. The adsorption process of Hg(II) and Cr(VI) followed the pseudo-second-order kinetics, and the rate-limiting step in the adsorption was chemisorption. The Weber-Morris intraparticle pore diffusion model revealed that the Hg(II) and Cr(VI) adsorption over CNTs-PLA-Pd occurs through multiple phases. The experimental equilibrium parameters for the Hg(II) and Cr(VI) adsorption were estimated by Langmuir, Freundlich, and Temkin isotherms models. All three models were well suited and demonstrated that Hg(II) and Cr(VI) adsorption over CNTs-PLA-Pd transpires through monolayer molecular covering and chemisorption.
| S-EPMC10304972 | biostudies-literature
Project description:This study investigated the removal of Total Organic Carbon (TOC) from produced water by batch adsorption process using adsorbents developed from Multi-Walled Carbon Nanotubes (MWCNTs). The MWCNTs, synthesized by catalytic chemical vapour deposition method using kaolin-supported tri-metallic (iron-cobalt-nickel) catalyst were purified by H2SO4/HNO3 and then functionalized with 1-pyrenebutanoic acid N-hydroxyl succinimidyl ester (PSE). The raw, purified and functionalized MWCNTs were characterized by High Resolution Scanning Electron Microscopy (HRSEM), High Resolution Transmission Electron Microscopy (HRTEM), Brunauer-Emmett-Teller (BET) and Fourier Transform Infrared Spectroscopy (FTIR). In the results, HRSEM/HRTEM revealed the structure, purity and also confirmed the attachment of the PSE molecule onto the nano-adsorbent(s). The BET surface areas of MWCNTs, PMWCNTs and FMWCNTs were 970.17, 869.25 and 831.80 m2/g, respectively while the FTIR established the existence of surface functional groups. The functionalized MWCNTs (FMWCNTs) nano-adsorbent showed superior performance efficiency (93.6%) than the purified MWCNTs (PMWCNTs) (79.2%) as examined under the same batch adsorption condition: 0.02 g adsorbent dosage, 10-90 min contact time and 30 °C solution temperature probably, due the improved wettability resulted from incorporation of PSE. Subsequently, Central Composite Design (CCD) was applied to optimize the process parameters for the sorption of TOC onto FMWCNTs. The CCD in the response surface methodology predicted 260 mg/g adsorption capacity of FMWCNTs in the removal of TOC at the optimum condition of 49.70 min contact time, 34.81 °C solution temperature, and 0.02 g adsorbent dosage. The kinetics data were best described by pseudo-second-order model and thermodynamic parameters suggested that the process was feasible, spontaneous and exothermic. It can be inferred from the various analysis conducted that the developed FMWCNTs nano-adsorbent is effective for removal of TOC from oil-produced water and may be explored for removal of organic contaminants from other industrial wastewater.
| S-EPMC7797377 | biostudies-literature
Project description:Two widely used anticancer drugs, doxorubicin (DOX) and paclitaxel (PTX), possess distinct physical properties and chemotherapy specificity. In order to investigate their interaction mechanism with single-walled carbon nanotubes (SWCNTs), co-loading and releasing from the SWCNTs, all-atom molecular dynamics (MD) simulations were firstly carried out for different SWCNT systems, followed by binding free energy calculation with MM-PBSA. The results indicate that the co-loading of DOX and PTX onto the pristine SWCNT is exothermic and spontaneous. The DOX molecules predominantly interact with the SWCNT via ?-? stacking through the conjugated aromatic rings, while the separated aromatic rings of PTX also primarily interact with the SWCNT through ?-? stacking yet supplemented by an X-? (X = C-H, N-H and C[double bond, length as m-dash]O) interaction. Moreover, the strongest binding of DOX and PTX with the pristine SWCNT shows similar strength (?G: -32.0 vs. -33.8 kcal mol-1). For the chitosan functionalized SWCNT (f-SWCNT), the DOX and PTX molecules still prefer binding to the sidewall of the CNT rather than binding with the polymer, and the non-covalent functionalization of the SWCNT with chitosan decreases the binding of DOX and PTX with the sidewall of the f-SWCNT as compared with the DOX/PTX-SWCNT system (?G: -24.0 and -21.9 kcal mol-1). The protonation of chitosan and drug molecules further weakens the interaction between DOX/PTX and the f-SWCNT, and shows a consequent displacement of the drug molecules, triggering the release of the drugs. The variation of binding strength of the three systems (DOX/PTX-SWCNT, DOX/PTX-f-SWCNT, and DOXH+/PTXH+-f-SWCNT) was also discussed in terms of the histogram or frequency of the distance from the drugs to the SWCNT. In addition, the encapsulation of two DOX molecules by the f-SWCNT is considerably stronger than the binding of the other six drug molecules to the sidewall, indicating that the encapsulation of anticancer drugs may also play a very important role and should be considered in the drug delivery.
| S-EPMC5898243 | biostudies-literature
Project description:In this study, we report a detailed experimental, binding free energy calculation and molecular dynamics (MD) simulation investigation of the interactions of carboxylic-functionalized multi-walled carbon nanotubes (COOH-f-MWCNTs) with porcine trypsin (pTry). The enzyme exhibits decreased thermostability at 330K in the presence of COOH-f-MWCNTs. Furthermore, the activity of pTry also decreases in the presence of COOH-f-MWCNTs. The restricted diffusion of the substrate to the active site of the enzyme was observed in the experiment. The MD simulation analysis suggested that this could be because of the blocking of the S1 pocket of pTry, which plays a vital role in the substrate selectivity. The intrinsic fluorescence of pTry is quenched with increase in the COOH-f-MWCNTs concentration. Circular dichroism (CD) and UV-visible absorption spectroscopies indicate the ability of COOH-f-MWCNTs to experience conformational change in the native structure of the enzyme. The binding free energy calculations also show that electrostatics, ?-cation, and ?-? stacking interactions play important roles in the binding of the carboxylated CNTs with pTry. The MD simulation results demonstrated that the carboxylated CNTs adsorb to the enzyme stronger than the CNT without the-COOH groups. Our observations can provide an example of the nanoscale toxicity of COOH-f-MWCNTs for proteins, which is a critical issue for in vivo application of COOH-f-MWCNTs.
| S-EPMC5983559 | biostudies-literature
Project description:With special properties such as excellent fluoresce features, low toxicity, good biocompatibility, permeability, and easy clearance from the body, carbon dot (CD)-based nanoparticles (NPs) have the potential to deliver drugs and use in vivo diagnostics through molecular imaging. In this work, folic acid-CD (FA-CD) NPs were prepared to deliver doxorubicin (Dox) covalently and noncovalently as cancer theranostics. FA was conjugated to the surface of CDs for targeting cancer cells with overexpressing folate receptors. CDs prepared with various amounts of precursors lead to their associated NPs with different photoluminescence properties and drug release profiles. The loading of Dox and its releasing data depends on the linkage of drug Dox to FA-CD and CD composition. All NPs were characterized by UV-vis, Fourier transform infrared spectroscopy, and dynamic light scattering. The noncovalent FA-CD-Dox NPs were preferred with a simple preparation process, excellent photoluminescence, and in vitro drug release properties. The noncovalent FA-CD-Dox showed the best efficacy against MDA-MB-231 compared to the CD-Dox and covalent FA-CD-Dox.
| S-EPMC9280931 | biostudies-literature
Project description:The increasing prevalence of carbon nanotubes (CNTs) as components of new functional materials has the unintended consequence of causing increases in CNT concentrations in aqueous environments. Aqueous systems are reservoirs for bacteria, including human and animal pathogens, that can form biofilms. At high concentrations, CNTs have been shown to display biocidal effects; however, at low concentrations, the interaction between CNTs and bacteria is more complicated, and antimicrobial action is highly dependent upon the properties of the CNTs in suspension. Here, impact of low concentrations of multiwalled CNTs (MWCNTs) on the biofilm-forming opportunistic human pathogen Pseudomonas aeruginosa is studied. Using phase contrast and confocal microscopy, flow cytometry, and antibiotic tolerance assays, it is found that sub-lethal concentrations (2 mg/L) of MWCNTs promote aggregation of P. aeruginosa into multicellular clusters. However, the antibiotic tolerance of these "young" bacterial-CNT aggregates is similar to that of CNT-free cultures. Overall, our results indicate that the co-occurrence of MWCNTs and P. aeruginosa in aqueous systems, which promotes the increased number and size of bacterial aggregates, could increase the dose to which humans or animals are exposed.
| S-EPMC7386566 | biostudies-literature
Project description:Single-ion detection has, for many years, been the domain of large devices such as the Geiger counter, and studies on interactions of ionized gasses with materials have been limited to large systems. To date, there have been no reports on single gaseous ion interaction with microelectronic devices, and single neutral atom detection techniques have shown only small, barely detectable responses. Here we report the observation of single gaseous ion adsorption on individual carbon nanotubes (CNTs), which, because of the severely restricted one-dimensional current path, experience discrete, quantized resistance increases of over two orders of magnitude. Only positive ions cause changes, by the mechanism of ion potential-induced carrier depletion, which is supported by density functional and Landauer transport theory. Our observations reveal a new single-ion/CNT heterostructure with novel electronic properties, and demonstrate that as electronics are ultimately scaled towards the one-dimensional limit, atomic-scale effects become increasingly important.
| S-EPMC4737755 | biostudies-literature
Project description:In the field of electronic gas sensing, low-dimensional semiconductors such as single-walled carbon nanotubes (SWCNTs) can offer high detection sensitivity owing to their unprecedentedly large surface-to-volume ratio. The sensitivity and responsivity can further improve by increasing their areal density. Here, an accelerated gas adsorption is demonstrated by exploiting volumetric effects via dispersion of SWCNTs into a percolating three-dimensional (3D) network in a semiconducting polymer. The resultant semiconducting composite film is evaluated as a sensing membrane in field effect transistor (FET) sensors. In order to attain reproducible characteristics of the FET sensors, a pulsed-gate-bias measurement technique is adopted to eliminate current hysteresis and drift of sensing baseline. The rate of gas adsorption follows the Langmuir-type isotherm as a function of gas concentration and scales with film thickness. This rate is up to 5 times higher in the composite than only with an SWCNT network in the transistor channel, which in turn results in a 7-fold shorter time constant of adsorption with the composite. The description of gas adsorption developed in the present work is generic for all semiconductors and the demonstrated composite with 3D percolating SWCNTs dispersed in functional polymer represents a promising new type of material for advanced gas sensors.
| S-EPMC4758076 | biostudies-literature
Project description:This study concerns the development of folic acid (FA)-functionalized iron oxide condensed colloidal magnetic clusters for a more selective delivery of doxorubicin (DOX) to tumor cancer cells overexpressing the folate receptor. Alginate-coated condensed magnetic nanoparticles (co-MIONs) were synthesized via an alkaline precipitation method of an iron precursor in the presence of sodium alginate. Poly(ethylene glycol) (OH-PEG-NH2) was conjugated to the carboxylic acid end group of alginate and folic acid (FA) was conjugated to the hydroxyl terminal group of PEG to produce folate-functionalized, pegylated co-MIONS (Mag-Alg-PEG-FA). The physicochemical properties of nanoparticles were fully characterized. DOX was loaded on the nanoparticles, and the cellular uptake and anticancer efficacy of the nanoparticles were examined in cancer cell lines expressing and not expressing the folate receptor. The biocompatibility of the carrier (blank nanoparticles) was also evaluated by cytocompatibility and hemocompatibility experiments. The nanoparticles exhibited sustained DOX release in aqueous buffers and biorelevant media, which was responsive to pH and external alternating current magnetic fields. The effect of the magnetic field on DOX percentage release appeared to be independent of the timing (onset time) of magnetic field application, providing flexibility to the magnetic control of drug release from the nanoparticles. The blank nanoparticles were not cytotoxic and did not cause hemolysis. The DOX-loaded and FA-functionalized nanoparticles exhibited increased uptake and caused increased apoptosis and cytotoxicity against the MDA-MB-231 cell line, expressing the folate receptor, compared to the MCF-7 cell line, not expressing the folate receptor. The application of a 0.5 T magnetic field during incubation of the nanoparticles with the cancer cells increased the cellular uptake and cytotoxicity of the nanoparticles. The obtained results indicate the potential of the folate-functionalized, pegylated co-MIONS for a more efficacious DOX delivery to cancer cells of solid tumors.
| S-EPMC6933766 | biostudies-literature