Ultra-low concentration protein detection based on phenylalanine-Pd/SWCNT as a high sensitivity nanoreceptor.

Pd doped single-walled carbon nanotubes as an enhanced physical transducer with phenylalanine amino acid can be efficiently used as a biocompatible nanoreceptor to detect proteins. DFT/B3LYP was used to calculate the optimized geometries, energies and electron density parameters to determine the stability and reactivity of the nanoreceptor. Among different adsorbed configurations of phenylalanine, the amine and carboxylic acid sites have higher adsorption energies and more stable complexes. With direct strong chemical adsorption of phenylalanine amino acid onto the Pd doped single-walled carbon nanotube, the free active carboxylic acid group of the amino acid can react with free amine groups on the surface of the proteins. More over the π-π stacking interaction between the free aromatic ring of adsorbed phenylalanine amino acid onto the functionalized single-walled carbon nanotube and the aromatic rings of the proteins also contributes to the intelligent detection of proteins. Frontier molecular orbital and molecular electrostatic potential (MPE) surface studies have been employed to investigate the active sites of the nanoreceptor. The effects of different solvents on the structural and electronic properties were investigated. Finally, in order to investigate biological function of the biosensor, docking studies were performed.

Encapsulation efficiency of single-walled carbon nanotube for Ifosfamide anti-cancer drug.

The encapsulation efficiency of (10,10) armchair single-walled carbon nanotubes as a nanovector for Ifosfamide anti-cancer drug has been investigated. (10,10) armchair single-walled carbon nanotube was selected because of larger inner volume for encapsulation, distinct inner and outer surfaces for functionalization and penetration possibility into cells or cell nucleus. Moreover, the adverse side effects of Ifosfamide can be reduced by single-walled carbon nanotubes. A complete understanding of the encapsulation process of drug molecules into carbon nanotubes is necessary for drug delivery development. All possible stable conformers of the drug have been investigated through geometry optimizations at the B3LYP/6-31G**level of theory by using the Gaussian 09 suite of programs and then encapsulation of the most stable conformer has been studied. Results show that the Ifosfamide drug molecule can be encapsulated into the internal cavity of armchair single-walled carbon nanotube. The corresponding adsorption energy is -3.87 eV. Furthermore, the effects of encapsulation on the electronic properties of the carbon nanotube such as equilibrium distances, HOMO-LUMO energy gap and DFT based descriptors have been also probed. Quantum mechanical calculations of encapsulation verify that a single-walled carbon nanotube could adsorb an Ifosfamide molecule spontaneously via the chemisorption process.

Leucine/Pd-loaded (5,5) single-walled carbon nanotube matrix as a novel nanobiosensors for in silico detection of protein.

We have designed a novel nanobiosensor for in silico detecting proteins based on leucine/Pd-loaded single-walled carbon nanotube matrix. Density functional theory at the B3LYP/6-31G (d) level of theory was realized to analyze the geometrical and electronic structure of the proposed nanobiosensor. The solvent effects were investigated using the Tomasi's polarized continuum model. Atoms-in-molecules theory was used to study the nature of interactions by calculating the electron density ρ(r) and Laplacian at the bond critical points. Natural bond orbital analysis was performed to achieve a deep understanding of the nature of the interactions. The biosensor has potential application for high sensitive and rapid response to protein due to the chemical adsorption of L-leucine amino acid onto Pd-loaded single-walled carbon nanotube and reactive functional groups that can incorporate in hydrogen binding, hydrophobic interactions and van der Waals forces with the protein surface in detection process.

Nanocarrier for levodopa Parkinson therapeutic drug; comprehensive benserazide analysis.

Loss of dopamine-secreting neurons in the midbrain causes Parkinson's disease. L-DOPA, the precursor to the neurotransmitters dopamine, crosses vast majority of physiological and biochemical barriers that dopamine cannot. But most levodopa is decarboxylated to dopamine before it reaches the brain. This causes to little therapeutic gain with strong peripheral side effects. Benserazide is an irreversible inhibitor of peripheral aromatic L-amino acid decarboxylase that prevents the breakdown of levodopa in the bloodstream. The challenges are to increase the therapeutic efficiency, the bioavailability and decreasing the unfavourable side effects of Levodopa drug. Biocompatible nano-sized drug carriers could address these challenges at molecular level. Thus calculations of drug loading ability of acid-functionalized CNT for the benserazide as a nanodug carrier complex for L-DOPA were performed. In this regard, evaluation of all adsorption features of the most stable conformer of benserazide molecule onto carboxylated carbon nanotube is critical. To determine the minimum energy conformer of benserazide, the molecular structure and conformational analysis of 512 possible conformers have been subjected to first principle quantum mechanical calculations. Our work established a novel and easy-to-make formulation of benserazide/carboxylated CNT conjugate with extremely high drug loading efficiency of Levodopa for Parkinson disease treatment.