Novel thymoquinone lipidic core nanocapsules with anisamide-polymethacrylate shell for colon cancer cells overexpressing sigma receptors

The biggest challenge in colorectal cancer therapy is to avoid intestinal drug absorption before reaching the colon, while focusing on tumor specific delivery with high local concentration and minimal toxicity. In our work, thymoquinone (TQ)-loaded polymeric nanocapsules were prepared using the nanoprecipitation technique using Eudragit S100 as polymeric shell. Conjugation of anisamide as a targeting ligand for sigma receptors overexpressed by colon cancer cells to Eudragit S100 was carried out via carbodiimide coupling reaction, and was confirmed by thin layer chromatography and ¹H-NMR. TQ nanocapsules were characterized for particle size, surface morphology, zeta potential, entrapment efficiency % (EE%), in vitro drug release and physical stability. A cytotoxicity study on three colon cancer cell lines (HT-29, HCT-116, Caco-2) was performed. Results revealed that the polymeric nanocapsules were successfully prepared, and the in vitro characterization showed a suitable size, zeta potential, EE% and physical stability. TQ exhibited a delayed release pattern from the nanocapsules in vitro. Anisamide-targeted TQ nanocapsules showed higher cytotoxicity against HT-29 cells overexpressing sigma receptors compared to their non-targeted counterparts and free TQ after incubation for 48 h, hence delineating anisamide as a promising ligand for active colon cancer targeting.

Ultrasonic assisted synthesis of two new coordination polymers and their applications as precursors for preparation of nano-materials

Two new isostructural coordination polymers, [Zn₃(Oba)₄][Me₂NH₂)₂]·6DMF·3H₂O (1) and [Cd₃(Oba)₄][Me₂NH₂)₂]·2DMF·2H₂O (2), were synthesized using the nonlinear dicarboxylate ligand, 4,4'-oxybis(benzoic acid) (H₂oba) and characterized by IR spectroscopy and single-crystal X-ray crystallography. Single-crystal X-ray data show that 1 and 2 are two-dimensional coordination polymers that can be extended to three-dimensional supramolecular networks by CH…O interactions. These two new coordination polymers were also sonochemically synthesized while sonication time and power of irradiation influencing size and morphology of nano-structured compounds were also studied. Moreover, calcination of these coordination polymers creates ZnO and CdO nanostructures.

High adsorption capacity of two Zn-based metal-organic frameworks by ultrasound assisted synthesis

Micro- and nano-rods and plates of two 3D, porous Zn(II)-based metal-organic frameworks [Zn(oba)(4-bpdh)0.5]n·(DMF)1.5 (TMU-5) and [Zn(oba)(4-bpmb)0.5]n (DMF)1.5 (TMU-6) were prepared by sonochemical process and characterized by scanning electron microscopy, X-ray powder diffraction and IR spectroscopy. These MOFs were synthesized using a non-linear dicarboxylate (H2oba=4,4-oxybisbenzoic acid) and two linear N-donor (4-bpdh=2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene and 4-bpmb=N(1),N(4)-bis((pyridin-4-yl)methylene)benzene-1,4-diamine) ligands by ultrasonic irradiation. Sonication time and concentration of initial reagents influencing size and morphology of nano-structured MOFs, were also studied. Calcination of TMU-5 and TMU-6 at 550°C under air atmosphere yields ZnO nanoparticles. TMU-5 and TMU-6 exhibited maximum percent adsorption of 96.2% and 92.8% of 100ppm rhodamine B dye, respectively, which obeys first order reaction kinetics.

Role of zinc interstitials and oxygen vacancies of ZnO in photocatalysis: a bottom-up approach to control defect density

Oxygen vacancies (V(O)s) in ZnO are well-known to enhance photocatalytic activity (PCA) despite various other intrinsic crystal defects. In this study, we aim to elucidate the effect of zinc interstitials (Zn(i)) and V(O)s on PCA, which has applied as well as fundamental interest. To achieve this, the major hurdle of fabricating ZnO with controlled defect density requires to be overcome, where it is acknowledged that defect level control in ZnO is significantly difficult. In the present context, we fabricated nanostructures and thoroughly characterized their morphological (SEM, TEM), structural (XRD, TEM), chemical (XPS) and optical (photoluminescence, PL) properties. To fabricate the nanostructures, we adopted atomic layer deposition (ALD), which is a powerful bottom-up approach. However, to control defects, we chose polysulfone electrospun nanofibers as a substrate on which the non-uniform adsorption of ALD precursors is inevitable because of the differences in the hydrophilic nature of the functional groups. For the first 100 cycles, Zn(i)s were predominant in ZnO quantum dots (QDs), while the presence of V(O)s was negligible. As the ALD cycle number increased, V(O)s were introduced, whereas the density of Zn(i) remained unchanged. We employed PL spectra to identify and quantify the density of each defect for all the samples. PCA was performed on all the samples, and the percent change in the decay constant for each sample was juxtaposed with the relative densities of Zn(i)s and V(O)s. A logical comparison of the relative defect densities of Zn(i)s and V(O)s suggested that the former are less efficient than the latter because of the differences in the intrinsic nature and the physical accessibility of the defects. Other reasons for the efficiency differences were elaborated.

Ultrasound assisted synthesis of a Zn(ii) metal–organic framework with nano-plate morphology using non-linear dicarboxylate and linear N-donor ligands

Nano-plates of TMU-4 were obtained upon ultrasonic irradiation.

Synthesis and characterization of a calix[4]arene amphiphilie bearing cysteine and uniform Au nanoparticle formation templated by its four cysteine moieties

A novel calix[4]arene amphiphilic molecule, denoted by CCaL3, was synthesized and found to form a spherical micelle consisting of 12 molecules at low pH in aqueous solution. Furthermore, uniform Au nanoparticles with 2.0 nm in diameter were synthesized in aqueous solution on the template consisting of the four cysteines of the upper rim of CCaL3. Asymmetric field flow fractionation coupled with light scattering showed that there was no dispersity in the CCaL3 micellar aggregation number. When AuCl4(-) ions were added into the CCaL3 micelle solution, induced circular dichroism (ICD) appeared, indicating appearance of the structural chirality of the CCaL3/AuCl4(-) complex. A combination of electron microscopy and small-angle X-ray scattering showed that helically coiled bilayer sheets were formed upon addition of AuCl4(-). Subsequent reduction with the amine of cysteine moieties led to uniform Au nanoparticles formation with 2.0 nm in diameter on the micellar plate surface. The nanoparticle size was almost equal to the size of cavity constructed by the four cysteines on the calix[4]arene upper rim, indicating that the growth of Au nanoparticles was spatially controlled by the host-guest interaction between the cysteines and Au.