Organically surface engineered mesoporous silica nanoparticles control the release of quercetin by pH stimuli.

Controlling the premature release of hydrophobic drugs like quercetin over physiological conditions remains a challenge motivating the development of smart and responsive drug carriers in recent years. This present work reported a surface modification of mesoporous silica nanoparticles (MSN) by a functional compound having both amines (as a positively charged group) and carboxylic (negatively charged group), namely 4-((2-aminoethyl)amino)-4-oxobut-2-enoic acid (AmEA) prepared via simple mechanochemistry approach. The impact of MSN surface modification on physical, textural, and morphological features was evaluated by TGA, N2 adsorption-desorption, PSA-zeta, SEM, and TEM. The BET surface area of AmEA-modified MSN (MSN-AmEA) was found to be 858.41 m2 g-1 with a pore size of 2.69 nm which could accommodate a high concentration of quercetin 118% higher than MSN. In addition, the colloidal stability of MSN-AmEA was greatly improved as indicated by high zeta potential especially at pH 4 compared to MSN. In contrast to MSN, MSN-AmEA has better in controlling quercetin release triggered by pH, thanks to the presence of the functional groups that have a pose-sensitive interaction hence it may fully control the quercetin release, as elaborated by the DFT study. Therefore, the controlled release of quercetin over MSN-AmEA verified its capability of acting as a smart drug delivery system.

Synthesis, structure and luminescence properties of a cadmium(II)-based coordination polymer with (S)-4,4'-bis(4-carboxyphenyl)-2,2'-bis(diphenylphosphinoyl)-1,1'-binaphthyl as chiral linker.

Solvothermal reaction of cadmium(II) nitrate with (S)-4,4'-bis(4-carboxyphenyl)-2,2'-bis(diphenylphosphinoyl)-1,1'-binaphthyl (H2L) in dimethylformamide (dmf) gave the two-dimensional chiral coordination polymer [{Cd2(L)2(H2O)}·18 dmf]n (1), which is thermally stable up to 400 °C according to DTA/TG analysis. According to single-crystal X-ray analysis, 1 forms layers in the [1[combining macron]01] direction, which are relatively well separated from each other. Compound L exhibits ligand-based bluish luminescence, assigned to the S1→S0 transition of the aromatic units in L. Emission spectra consist of nearly Gaussian shaped bands with maxima at 25,574 and 24,767 cm(-1) for H2L and 1, respectively. Quantum efficiency reaches a remarkably high value of 42% for the Cd-based coordination polymer and 33% for the respective ligand. Emission intensity of increases from 10 K to room temperature and decreases exponentially for temperatures up to 650 K.