Exploring pH dependent delivery of 5-fluorouracil from functionalized multi-walled carbon nanotubes

Effect of functionalization on the adsorption performance of carbon nanotube as a drug delivery system for imatinib: molecular simulation study

In this study, efficiency of functionalized carbon nanotube as a potential delivery system for imatinib anti-cancer drug was investigated. Accordingly, carboxyl and hydroxyl functionalized carbon nanotube were inspected as a notable candidate for the carriage of this drug in aqueous media. For this purpose, possible interactions of imatinib with pure and functionalized carbon nanotube were considered in aqueous media. The compounds were optimized in gas phase using density functional calculations. Solvation free energies and association free energies of the optimized structures were then studied by Monte Carlo simulation and perturbation method in water environment. Outcomes of quantum mechanical calculations presented that pure and functionalized carbon nanotubes can act as imatinib drug adsorbents in gas phase. However, results of association free energy calculations in aqueous solution indicated that only carboxyl and hydroxyl functionalized carbon nanotubes could interact with imatinib. Monte Carlo simulation results revealed that electrostatic interactions play a vital role in the intermolecular interaction energies after binding of drug and nanotube in aqueous solution. Computed solvation free energies in water showed that the interactions with functionalized carbon nanotubes significantly enhance the solubility of imatinib, which could improve its in vivo bioavailability.

A Review on Carbon Nanotubes Family of Nanomaterials and Their Health Field

The use of carbon nanotubes (CNTs), which are nanometric materials, in pathogen detection, protection of environments, food safety, and in the diagnosis and treatment of diseases, as efficient drug delivery systems, is relevant for the improvement and advancement of pharmacological profiles of many molecules employed in therapeutics and in tissue bioengineering. It has contributed to the advancement of science due to the development of new tools and devices in the field of medicine. CNTs have versatile mechanical, physical, and chemical properties, in addition to their great potential for association with other materials to contribute to applications in different fields of medicine. As, for example, photothermal therapy, due to the ability to convert infrared light into heat, in tissue engineering, due to the mechanical resistance, flexibility, elasticity, and low density, in addition to many other possible applications, and as biomarkers, where the electronic and optics properties enable the transduction of their signals. This review aims to describe the state of the art and the perspectives and challenges of applying CNTs in the medical field. A systematic search was carried out in the indexes Medline, Lilacs, SciELO, and Web of Science using the descriptors "carbon nanotubes", "tissue regeneration", "electrical interface (biosensors and chemical sensors)", "photosensitizers", "photothermal", "drug delivery", "biocompatibility" and "nanotechnology", and "Prodrug design" and appropriately grouped. The literature reviewed showed great applicability, but more studies are needed regarding the biocompatibility of CNTs. The data obtained point to the need for standardized studies on the applications and interactions of these nanostructures with biological systems.

Nanoparticle-based materials in anticancer drug delivery: Current and future prospects

The past decade has witnessed a breakthrough in novel strategies to treat cancer. One of the most common cancer treatment modalities is chemotherapy which involves administering anti-cancer drugs to the body. However, these drugs can lead to undesirable side effects on healthy cells. To overcome this challenge and improve cancer cell targeting, many novel nanocarriers have been developed to deliver drugs directly to the cancerous cells and minimize effects on the healthy tissues. The majority of the research studies conclude that using drugs encapsulated in nanocarriers is a much safer and more effective alternative than delivering the drug alone in its free form. This review provides a summary of the types of nanocarriers mainly studied for cancer drug delivery, namely: liposomes, polymeric micelles, dendrimers, magnetic nanoparticles, mesoporous nanoparticles, gold nanoparticles, carbon nanotubes and quantum dots. In this review, the synthesis, applications, advantages, disadvantages, and previous studies of these nanomaterials are discussed in detail. Furthermore, the future opportunities and possible challenges of translating these materials into clinical applications are also reported.

The D-amino acid oxidase-carbon nanotubes: evaluation of cytotoxicity and biocompatibility of a potential anticancer nanosystem

The 'enzyme prodrug therapy' represents a promising strategy to overcome limitations of current cancer treatments by the systemic administration of prodrugs, converted by a foreign enzyme into an active anticancer compound directly in tumor sites. One example is D-amino acid oxidase (DAAO), a dimeric flavoenzyme able to catalyze the oxidative deamination of D-amino acids with production of hydrogen peroxide, a reactive oxygen species (ROS), able to favor cancer cells death. A DAAO variant containing five aminoacidic substitutions (mDAAO) was demonstrated to possess a better therapeutic efficacy under low O2 concentration than wild-type DAAO (wtDAAO). Recently, aiming to design promising nanocarriers for DAAO, multi-walled carbon nanotubes (MWCNTs) were functionalized with polyethylene glycol (PEG) to reduce their tendency to aggregation and to improve their biocompatibility. Here, wtDAAO and mDAAO were adsorbed on PEGylated MWCNTs and their activity and cytotoxicity were tested. While PEG-MWCNTs-DAAOs have shown a higher activity than pristine MWCNTs-DAAO (independently on the DAAO variant used), PEG-MWCNTs-mDAAO showed a higher cytotoxicity than PEG-MWCNTs-wtDAAO at low O2 concentration. In order to evaluate the nanocarriers' biocompatibility, PEG-MWCNTs-DAAOs were incubated in human serum and the composition of protein corona was investigated via nLC-MS/MS, aiming to characterize both soft and hard coronas. The mDAAO variant has influenced the bio-corona composition in both number of proteins and presence of opsonins and dysopsonins: notably, the soft corona of PEG-MWCNTs-mDAAO contained less proteins and was more enriched in proteins able to inhibit the immune response than PEG-MWCNTs-wtDAAO. Considering the obtained results, the PEGylated MWCNTs conjugated with the mDAAO variant seems a promising candidate for a selective antitumor oxidative therapy: under anoxic-like conditions, this novel drug delivery system showed a remarkable cytotoxic effect controlled by the substrate addition, against different tumor cell lines, and a bio-corona composition devoted to prolong its blood circulation time, thus improving the drug's biodistribution.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03568-1.

Theoretical studies of phosphorene as a drug delivery nanocarrier for fluorouracil

The interactions between phosphorene nanosheets (PNSs) and 5-fluorouracil (FLU) were explored using the density functional theory (DFT) method and molecular dynamics (MD) simulations. DFT calculations were performed utilizing M06-2X functional and the 6-31G(d,p) basis set in both gas and solvent phases. Results showed that the FLU molecule is adsorbed horizontally on the PNS surface with an adsorption energy (Eads) of -18.64 kcal mol-1. The energy gap (Eg) between the highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO, respectively) of PNS remains constant after the adsorption process. The adsorption behavior of PNS is not affected by carbon and nitrogen doping. The dynamical behavior of PNS-FLU was studied at T = 298, 310, and 326 K reminiscent of room temperature, body temperature, and temperature of the tumor after exposure to 808 nm laser radiation, respectively. The D value decreases significantly after the equilibration of all systems so that the equilibrated value of D is about 1.1 × 10-6, 4.0 × 10-8, and 5.0 × 10-9 cm2 s-1 at T = 298, 310, and 326 K, respectively. About 60 FLU molecules can be adsorbed on both sides of each PNS, indicating its high loading capacity. PMF calculations demonstrated that the release of FLU from PNS is not spontaneous, which is favorable from a sustained drug delivery point of view.

Binding mechanism and SERS spectra of 5-fluorouracil on gold clusters

The adsorption behaviour of the 5-fluorouracil (5FU) on small gold clusters Au _N with N = 6, 8, 20 was evaluated by means of density functional theory using the PBE-D3 functional in combination with a mixed basis set, i.e. cc-pVDZ-PP for gold atoms and cc-pVTZ for non-metal elements. The binding energies between 5FU and gold clusters were determined in the range of 16-24 and 11-19 kcal/mol in gas-phase and aqueous media, respectively. The corresponding Gibbs energies were found to be around -7 to -10 kcal/mol in vacum and sigificantly reduced to -1 to -6 kcal/mol in water solution, indicating that both the association and dissociation processes are likely spontaneous. An analysis on the charge density difference tends to confirm the existence of a charge transfer from the 5FU molecule to Au atoms. Analysis of the surface-enhanced Raman scattering (SERS) spectra of 5FU adsorbed on the Au surfaces shows that the stretching vibrations of N-H and C=O bonds play a major role in the SERS phenomenon. A mechanism for the drug releasing from the gold surfaces is also proposed. The process is triggered by either the low pH in cancerous tumors or the presence of cysteine residues in protein matrices.

Potential of novel self-assembled functionalized carbon nanotubes for selective tumor targeting

Conventional cancer therapies are associated with toxicity toward healthy cells, which need to be addressed by novel therapeutic approaches. US2021/0230592 patent application discloses a carbon nanotube-based approach for tumor targeting, wherein a self-assembling single-wall nanotube complex has been developed and functionalized to deliver a molecule to a cancerous cell. The radiolabeled nanotubes exhibited markedly reduced toxicity as they did not depict any 'over toxicity' up to radioactivity value of 1350 nCi. The single-wall carbon nanotube conjugates were covalently connected to several chelators, therapeutic or diagnostic radionuclides, and showed promising results in the effective cancer management. Besides, this invention with further modifications paves an ideal pathway to researchers in effective diagnosis and treatment of cancer.

Efficient synthesis of 1,3-naphtoxazine derivatives using reusable magnetic catalyst (GO-Fe3O4-Ti(IV)): anticonvulsant evaluation and computational studies

A series of 2-aryl/alkyl-2,3-dihydro-1H-naphtho[1,2-e][1,3]oxazines (S₁-S₁₁) were synthesized with an eco-friendly and recoverable nanocatalyst (GO-Fe₃O₄-Ti^(IV)) as an efficient magnetic composite. The new nanocatalyst was characterized by FT-IR, XRD and, EDS analysis. A conformable procedure, easy to work up and having a short reaction time with high yields are some advantages of this method. The new catalyst is also thermal-stable, reusable and, environment-friendly. The chemical structures of the synthesized 1,3-oxazine compounds were confirmed by comparing their melting points with those reported in literature. Then, the anticonvulsant activity of these compounds was assessed by the intraperitoneal pentylenetetrazole test (ipPTZ). Compounds S₁₀ and S₁₁ displayed considerable activity against chemically-induced seizure tests. The molecular simulation was also done to achieve their binding affinities as γ-aminobutyric acid A (GABA-A) receptor agonists as an assumptive mechanism of their anticonvulsant action. The result of molecular studies represented strongly matched with biological activity. Molecular docking simulation of the potent compound (S₁₀) and diazepam as the positive control was performed and some critical residues like Thr262, Asn265, Met286, Phe289, and Val290 were identified. Based on the anticonvulsant results and also in silico ADME predictions, S₁₁ can be to become a potential drug candidate as an anticonvulsant agent.

Regulation of water access, storage, separation and release of drugs from the carbon nanotube functionalized by cytosine rich DNA fragments

We found that carmustine can be stored in the carbon nanotube (CNT) interior for a long time due to hydrophobic interactions. The access of water to carmustine phase in the CNT interior can be controlled by the state of cytosine rich DNA fragments covalently bound to the CNT tips and to the presence of doxorubicin molecules intercalated within bundles of DNA fragments. More effective control of water access and subsequent decomposition of carmustine due to the contact with water was observed when some small amount of doxorubicin molecules cork the CNT ends. Our analysis shows that carmustine decomposition products naturally separate when decomposition occurs within the CNT. The alkylating agent, chloroethyl carbonium cation, spontaneously escapes from the CNT but the carbamylation agent, chloroethyl isocyanate, is still kept within the nanotube interior. The separation process and release of the alkylating agent needs uncorking the nanotube by doxorubicin molecules. The latter process is likely to occur spontaneously at acidic pH when intercalation of doxorubicin within the DNA fragments becomes ineffective. The features of the proposed molecular model, obtained from molecular dynamics simulations, can be beneficial in design of novel smart drugs carriers to a tumor microenvironment revealing the reduced extracellular pH.

Hybrid Hosts Based on Sodium Alginate and Porous Clay Heterostructures for Drug Encapsulation

In this study, some hybrid materials based on sodium alginate (NaAlg) and porous clay heterostructures (PCHs) were investigated as new hosts for 5-Fluorouracil (5-FU) encapsulation. The hybrid hosts were prepared by ionotropic gelation technique using different concentrations of PCHs (1, 3, and 10 wt%) in order to identify the optimal parameters for encapsulation and drug release. The obtained hybrid materials were characterized using FTIR Spectrometry, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and UV-Vis spectrometry to investigate the interactions of the raw materials involved in the preparation of hybrid hosts, the influence of PCHs concentrations on drug encapsulation efficiency and drug release profile. All the results show that the synthesized hybrid materials were able to load a high amount of 5-FU, the encapsulation efficiency and the release profile being influenced by the concentrations of PCHs.