8 research outputs found
Metal-coated magnetic nanoparticles for surface enhanced Raman scattering studies
We report the optimization and usage of surfactantless, water dispersible Ag and Au-coated γ–Fe2O3 nanoparticles for applications in Surface-enhanced Raman Scattering (SERS). These nanoparticles, with plasmonic as well as super paramagnetic properties exhibit Raman enhancement factors of the order of 106 (105) for Ag (Au) coating, which are on par with the conventional Ag and Au nanoparticles. Raman markers like 2-naphthalenethiol, rhodamine-B and rhodamine-6G have been adsorbed to these nanoparticles and tested for nonresonant SERS at low concentrations. Further, to confirm the robustness of Ag-coated nanoparticles, we have performed temperature-dependent SERS in the temperature range of 77–473 K. The adsorbed molecules exhibit stable SERS spectra except at temperatures >323 K, where the thermal desorption of test molecule (naphthalenethiol) were evident. The magnetic properties of these nanoparticles combined with SERS provide a wide range of applications
Electrical Conductivity, Viscosity and Molar Volume of Potassium Nitrate - Sodium Nitrate in Cadmium Nitrate Tetrahydrate Melt
Viscosity and Molar Volume of Potassium Thiocyanate + Sodium Thiocyanate + Acetamide Melt Systems
Speeds of Sound and Viscosities of Potassium Thiocyanate in Water, Methanol, and Propylene Carbonate
Temperature and Pressure Dependence of the Electrical Conductivity of Two Tetraalkylammonium Tetraalkylborate Salts
Unravelling pH/pKa influence on pH-responsive drug carriers:Insights from ibuprofen-silica interactions and comparative analysis with carbon nanotubes, sulfasalazine, and alendronate
This study employs density functional theory to explore the interaction between ibuprofen (IBU) and silica, emphasizing the influence of the trimethylsilyl (TMS) functional group for designing pH-responsive drug carriers. The surface (S) and drug (D) molecules' neutral (0) or deprotonated (-1) states were taken into consideration during the investigation. The likelihood of these states was determined based on the pKa values and the desired pH conditions. To calculate the pH-dependent interaction energy (EintpH), four different situations have been identified: S0D0, S0D-1, S-1D0, and S-1D-1.The electrostatic component of interaction energy aligns favorably with its theoretical value in both the Debye-Hückel and Grahame models. The investigation has gathered first-hand experimental data on the drug loading and release of pH-responsive mesoporous silica nanoparticles. Effective drug loading was observed in the acidic environment of the stomach (pH 2-5), followed by a release in the slightly basic to neutral pH of the small intestine (pH 7.4), These findings align with existing literature. The results revealed horizontal drug adherence on silica surfaces, improving binding capabilities. Comparisons were made with combinations involving carboxylated carbon nanotubes and ibuprofen, silica, and sulfasalazine, and silica and alendronate, exploring drug loading/release dynamics associated with positive/negative interaction energies. The investigation, supported by experimental data, contributes valuable insights into pH-responsive mesoporous silica nanoparticles, offering new design possibilities for drug carriers.</p
Novel p<i>K</i><sub>a</sub>/DFT-Based Theoretical Model for Predicting the Drug Loading and Release of a pH-Responsive Drug Delivery System
Herein,
we present a theoretical model that combines classical
p<i>K</i><sub>a</sub> theory with quantum mechanical calculations
to predict the extent of interaction between acid-/base-dependent
species over a full range of pH conditions. To demonstrate the theoretical
model, we have predicted the drug loading and release of a pH-responsive
drug delivery system consisting of sulfasalazine, an anionic anti-inflammatory
drug molecule, loaded onto the positively charged trimethylammonium
(TA)-functionalized mesoporous silica nanoparticle surface. The model
relies on the possible combinations of pH-dependent states of the
surface (S) and drug (D) molecules as neutral (0) and deprotonated
(−1) states, whose relative probabilities depend on their p<i>K</i><sub>a</sub> value and the desired pH. The four possible
combinations were identified as S<sup>0</sup>D<sup>0</sup>, S<sup>0</sup>D<sup>–1</sup>, S<sup>–1</sup>D<sup>0</sup>,
and S<sup>–1</sup>D<sup>–1</sup>, and periodic density
functional theory calculations were performed for systems comprising
drug fragments adsorbed onto a model TA-functionalized quartz surface
to calculate the pH-dependent interaction energy (<i>E</i><sub>int</sub><sup>pH</sup>). The <i>E</i><sub>int</sub><sup>pH</sup> value was attractive at the acidic environment of stomach (pH 2–5),
where a drug is loaded and repulsive at neutral or slightly basic
pH in the small intestine where it is released; the behavior is in
accordance with the experimentally reported data. We also validated
the experimental necessity of surface functionalization