Biophysical chemistry of macrocycles for drug delivery: a theoretical study

Ab initio (RHF/STO-3G) quantum chemical calculations using the self-consistent reaction field (SCRF) model were carried out to analyze the effect of solvent polarity on the relative Gibbs free energies, the dipole moments, and the structural stability of peptide macrocycles based on unsubstituted cyclo[Gly₆] and its trisubstituted derivatives containing Me, NH₂, or OH groups at the Cα atom. The macrocycles studied are stable in water at both room temperature and at body fever temperature, which is important for the design of a stable nanovehicle for drug delivery in water.     

Engineering delivery of pantaprazole drug using multi-walled carbon nanotubes: an experimental and theoretical study

Structural Chemistry - Todays, using nano-based drug delivery systems as suitable carriers can help in controlling release of drug to target cells. In current study, multi-walled carbon nanotube...     

掺杂碳纳米管对五氯酚吸附作用的理论研究

为了寻找检测高毒性、持久性有机污染物五氯酚(PCP)的新型材料,应用密度泛函理论研究了(8,0)和(5,5)单壁碳纳米管(SWCNT)以及相应的Si、B和N掺杂的SWCNT对PCP分子的吸附性能.计算结果表明,(8,0)和(5,5)SWCNT与PCP分子之间为物理吸附;Si原子掺杂(8,0)和(5,5)SWCNT,引起了碳纳米管掺杂部位六元环的畸变,增强了SWCNT的反应活性,掺杂后的SWCNT对PCP分子形成化学吸附,其几何结构和电子性质发生了显著变化;B和N原子掺杂的SWCNT对PCP分子的吸附没有明显增强.Si原子掺杂的SWCNT最有潜力用于检测PCP分子.     

Computational studies on the doped graphene quantum dots as potential carriers in drug delivery systems for isoniazid drug

In this study, the application of graphene quantum dots (GQDs) and doped GQDs as potential carriers for the delivery of isoniazid (Iso) drug has been investigated, using density functional theory (DFT) calculations. For this purpose, the hexa-peri-hexabenzocoronene (as a GQD model) and its BN-, BP-, AlN-, and AlP-doped (C₃₆X₃Y₃H₁₈ where X = B, Al and Y = N, P) forms were selected. Our results indicated that the adsorption energies of isoniazid on doped GQDs were more negative than that of pure GQD. Moreover, the calculations showed that adsorption of isoniazid on AlN- and AlP-doped GQDs was thermodynamically favorable. The dipole moments of BP-, AlN-, and AlP-doped GQDs were much greater (5.799, 1.860, and 3.312 D, respectively) than that of pristine GQD (0 D). The AlN-Iso and AlP-Iso complexes had small energy gaps, low chemical potentials, and low global hardnesses, which were appropriate for their attachments to the target site. The nature of interactions was analyzed by the quantum theory of atoms in molecules (QTAIM) and noncovalent interaction (NCI) analyses. Overall, the results confirmed that the AlN- and AlP-doped GQDs could be used as potential carriers for drug delivery application.     

Sensing behavior of pristine and doped C70 fullerenes to mercaptopurine drug: a DFT/TDDFT investigation

Structural Chemistry - The electronic sensitivity and reactivity of a pristine, Al, and Si-doped C70 fullerene with MP drug were investigated using density functional theory. With adsorption energy...     

Screened exchange hybrid density-functional study of the work function of pristine and doped single-walled carbon nanotubes

We present a detailed study of the work function of pristine and doped single-walled carbon nanotubes (SWCNTs) using a novel screened exchange hybrid density functional. We find that SWCNTs with diameters larger than 0.9 nm tend asymptotically and smoothly to the graphene limit of 4.6 eV. On the other hand, the work function of narrow tubes exhibits a strong dependence on their diameter and chiral angle. Boron or nitrogen doping, with concentrations from 1% to 2%, not only changes the electronic behavior by introducing new states around the Fermi level, but also produces a significant change of the work function that can vary between 3.9 (N doping) and 5.2 eV (B doping).     

Magnetic nanotubes for magnetic-field-assisted bioseparation, biointeraction, and drug delivery

Tubular structure of nanoparticles is highly attractive due to their structural attributes, such as the distinctive inner and outer surfaces, over conventional spherical nanoparticles. Inner voids can be used for capturing, concentrating, and releasing species ranging in size from large proteins to small molecules. Distinctive outer surfaces can be differentially functionalized with environment-friendly and/or probe molecules to a specific target. Magnetic particles have been extensively studied in the field of biomedical and biotechnological applications, including drug delivery, biosensors, chemical and biochemical separation and concentration of trace amounts of specific targets, and contrast enhancement in magnetic resonance imaging (MRI). Therefore, by combining the attractive tubular structure with magnetic property, the magnetic nanotube (MNT) can be an ideal candidate for the multifunctional nanomaterial toward biomedical applications, such as targeting drug delivery with MRI capability. Here, we successfully synthesized magnetic silica-iron oxide composite nanotubes and demonstrated the magnetic-field-assisted chemical and biochemical separations, immunobinding, and drug delivery.     

Carbon nanotubes as potential material for drug delivery—experiment and simulation

We discuss the factors influencing the properties of new drug delivery system, composed of carbon nanotubes and analgesic antipyretic drug—paracetamol. Basing on experimental data it is shown, that by a simple manipulation with the heating time at the stage of system preparation, one can easily change the rate of the drug delivery. Moreover, this rate can be changed in a very wide range. Finally, using Molecular Dynamics simulation we also discuss the orientation and properties of drug molecules at different stages of the hot melt deposition process.     

Detection of paracetamol by armchair BN nanotubes: a molecular study

We have investigated structural and electronic properties of single wall (5,5) boron nitride nanotubes functionalized on the surface and at the ends with paracetamol (C₈H₉NO₂). Studies have been done within the density functional theory as implemented in DMol³ quantum chemistry code. The exchange and correlation energies have been treated according to the generalized gradient approximation with the Perdew–Burke–Ernzerhof parameterization and a basis function with double polarization. The geometry optimization of the (5,5) BNNT-Paracetamol system has been done using the criterion of minimum energy considering eight possible atomic interacting configurations. Simulation results show that the preferential interaction (physisorption) site of the paracetamol is on the nanotube surface in a parallel configuration and making an angle of 45° in the perpendicular direction to the nanotube. The BNNT-Paracetamol system experiences an increase in the polarity which favors the possible dispersion and solubility. As a result of the interaction, the functionalized nanotube chemical reactivity is increased. Provided the work function of the nondoped BNNT-Paracetamol structure decreases as compared with the pristine BNNT, the functionalized nanotubes yielded conditions to improve field emission properties consequently, they may be used as biosensors of paracetamol. Finally, the nanotube doped with carbon atoms induces chemisorption and an increase in the polarity, reactivity, and reduction in the work function. Taking into account, these results it may be suggested the use of the system in sensor devices and optoelectronic systems.     

A theoretical study on the pure and doped ZnO nanoclusters as effective nanobiosensors for 5-fluorouracil anticancer drug adsorption

The electronic sensitivity and effectiveness of the pristine, Fe,- Mg-, Al- and Ga-doped ZnO nanoclusters interacted with 5-fluorouracil (5-FU) anticancer drug are theoretically investigated in the gas phase using the B3LYP/wB97XD density functional theory calculations with LANL2DZ basis set. It is concluded that 5-FU adsorption on the doped nanoclusters has relatively higher adsorption energy as compared with the pristine zinc oxide. A number of thermodynamic parameters, such as band gap energy (E_g), adsorption energy (E_ad), molecular electrostatic potential, global hardness (η) and density of electronic states, are attained and compared. Also, calculated geometrical parameters and electronic properties for the studied systems indicate that Mg- and Ga-doped Zn₁₂O₁₂ present higher sensitivity to 5-FU compared with the pristine nanocluster. Theoretical results reveal that adsorption of 5-FU on the doped nanoclusters is influenced by the electronic conductance of the nanocluster. Therefore, Mg- and Ga-doped ZnO can be considered as promising nanobiosensors for detection of 5-FU in medicine.     

Atomic and electronic structures of fluorinated BN nanotubes: computational study

The atomic and electronic structures of fluorinated BN nanotubes (BNNTs) were investigated by generalized gradient approximation (GGA) density functional theory (DFT). The reaction energies of F2 with pristine single-walled BNNTs to form fluorinated BNNTs are exothermic up to 50% coverage. At lower F coverages (below 50%), fluorines prefer external attachments to boron atoms and stay as far away as possible. At 50% F coverage, fluorines favor attachment to all the boron atoms of the outer surface energetically. Such preferable fluorination patterns and highly exothermic reaction energies hold true for double-walled (and multiwalled) BNNTs when the outer tube surface is considered. Fluorination transforms BNNTs into p-type semiconductors at low F coverages, while high F coverages convert BNNTs into p-type conductors. Therefore, the electronic and transport properties of BNNTs can be engineered by fluorination, and this provides potential applications for fluorinated BNNTs in nanoelectronics.     

Molecular structures of alumina nanoballs and nanotubes: a theoretical study

Molecular structures of alumina nanoballs and nanotubes have been determined. Tetrahedral, octahedral, and icosahedral alumina nanostructures were derived from Platonic solids and Archimedean polyhedra and were optimized by quantum chemical methods. I(h)-symmetric balls, resembling their isovalence electronic analogues, fullerenes, are preferred. The nanoballs consist of adjacent Al(5)O(5) and Al(6)O(6) rings, similar to C(5)- and C(6)-rings of fullerenes. The structural characteristics of alumina nanoballs are dominated by pi-electron donation from oxygen to aluminum. Alumina nanotubes can be derived from icosahedral nanoballs. The tubes alternate between D(5d)- and D(5h)-symmetries and are capped by halves of the icosahedral balls.     

Preparation and drug controlled-release of polyion complex micelles as drug delivery systems

Block copolymers, poly(N-vinylprrolidone)-block-poly(styrene-alter-maleic anhydride) (PVP-b-PSMA) and poly(N-vinylprrolidone)-block-poly(N,N-dimethylaminoethyl methacrylate) (PVP-b-PDMAEMA), were synthesized by reversible addition- fragmentation chain transfer (RAFT) polymerization. In aqueous media, this a pair of oppositely-charged diblock copolymers could self-assemble into stable and narrow distribution polyion complex micelles (PICMs). Transmission electron micrographs (TEM) and dynamic light scattering (DLS) analysis showed that the micelles to be spherically shaped with mean hydrodynamic diameter around 70 nm. In addition, the PICMs display ability to response to external stimuli. All of theses features are quite feasible for utilizing it as a novel intelligent drug delivery system. In order to assess its application in biomedical area, release profiles of coenzyme A (Co A) from PICMs were studied under both simulated gastric and intestinal pH conditions. The release was much quicker in pH 7.4 buffer than in pH 2.0 solution. Based on these results, these PICMs could be a potential pH-sensitive carrier for colon-specific drug delivery system.     

Investigation of the solvent effect,molecular structure,electronic properties and adsorption mechanism of Tegafur anticancer drug on Graphene nanosheet surface as drug delivery system by molecular dynamics simulation and density functional approach

To understanding the adsorption mechanism and the induced effects of an anticancer drug, Tegafur molecule, on the surface of Graphene nanosheet (GNS) as a drug delivery system, we have performed density functional theory (DFT) and molecular dynamics (MD) methods. DFT calculations give valuable information on the structure, orientation, adsorption energy and charge transfer of nanosheet-molecule in the equilibrium GNS-Tegafur complexes in the gas phase as well as in the aqueous phase, i.e., water. The optimization of GNS-Tegafur geometries shows that drug molecule tends to adsorb via its six-membered aromatic ring to the hexagonal ring of Graphene nanosheet by π–π stacking interaction at the most stable physisorption configuration. Furthermore, the calculated solvation energy (E_sol) represented by a polarizable continuum model show the significant increase in the solubility of GNS after drug adsorption on its surface in the presence of H₂O solvent which leading to the possible applications of GNS in the drug delivery systems. MD simulation is also used to determine the effect of drug concentrations on dynamic properties of Tegafur adsorption on the GNS surfaces in the solution phase. Based on the obtained MD results, it is found that by increasing drug concentration, the van der Waals (vdW) interaction energy becomes more negative and the stabilities of the simulated complexes increase.     

Advances of nanoparticles as drug delivery systems for disease diagnosis and treatment

Decades have passed since the first nanoparticles-base medicine was approved for human cancer treatment, and the research and development of nanoparticles for drug delivery are always undergoing. Nowadays, the significant advances complicate nanoparticles’ branches, including liposomes, solid lipid nanoparticles, inorganic nanoparticles, micelles, nanovaccines and nano-antibodies, etc. These nanoparticles show numerous capabilities in treatment and diagnosis of stubborn diseases like cancer and neurodegenerative diseases, emerging as novel drug carriers or therapeutic agents in future. In this review, the complicated branches of nanoparticles are classified and summarized, with their property and functions concluded. Besides, there are also some delivery strategies that make nanoparticles smarter and more efficient in drug delivery, and frontiers in these strategies are also summarized in this review. Except these excellent works in newly-produced drug delivery nanoparticles, some points of view and future expectations are made in the end.     

A study of de-gassed oil in water dispersions as potential drug delivery systems

The natural hydrophobicity of many drugs makes it very difficult to use them for water-based intravenous injection. This lack of water solubility also hinders the development and testing of new drugs. Clinical tests are often refused if the drug can only be dissolved in water-insoluble oils and therefore cannot be administered safely or easily. However, we have discovered that de-gassing a mixture of a typical hydrophobic drug carrier oil and water produces, on vigorous shaking, a uniform fine dispersion of oil droplets, which are of suitable size for intravenous injection. These dispersions are stable and yet do not require the use of added stabilizing agents, such as surfactants and polymers, which can lead to harmful side effects. This novel process has been used to enhance the dispersion of the commonly used drug delivery oils, soybean oil and perfluorooctyl bromide (PFOB). This process can also be applied to other drug delivery oils, which are immiscible with water. For example, the dispersion of perfluorohexane in water is greatly improved by de-gassing. Over time, the dispersions phase separate but are easily re-generated simply by shaking, when stored under de-gassed conditions in sealed vials. The process has also been successfully applied to hydrophobic drugs, both liquid and solid, where dispersion was obtained without the use of either carrier oil or added dispersants. These dispersions offer safer drug delivery systems and also might be used in facilitating the development or testing of new experimental, water-insoluble drugs.     

Shortened single-walled carbon nanotubes modification as design of nano-structural drug delivery system for pharmaceutical substances

The synthesis of drug delivery system for pharmaceutical substances, represented by modified shortened single-walled carbon nanotubes, was realized. The synthesis was carried out via covalent grafting of water soluble linker to the graphene surface of single-walled carbon nanotubes, and resulted in stabilization of synthesized substance in water suspension.

     

Functionalized carbon nanomaterials as nanocarriers for loading and delivery of a poorly water-soluble anticancer drug: a comparative study

Carbon nanomaterials such as multiwalled carbon nanotubes (MWCNTs) and graphene oxide (GO) have been functionalized by highly hydrophilic and biocompatible poly(vinyl alcohol) (PVA) for loading and delivery of an anticancer drug, camptothecin (CPT). For the first time, CPT was loaded onto MWCNT-PVA and GO-PVA through π-π interactions and its capability to kill human breast and skin cancer cells was investigated.