Biopolymer collagen-chitosan scaffold containing Aloe vera for chondrogenic efficacy on cartilage tissue engineering.

The chondrogenic efficacy of aloe vera blended collagen-chitosan (COL-CS-AV) porous scaffold was investigated using articular chondrocytes in a standard condition. Cytocompatibility was analyzed using fluorescent dyes (calcein AM/ethidium bromide) and the viable cells were quantified by MTT assay. Glycosaminoglycan (GAG) content of ECM was estimated by using 1, 9-Dimethyl methylene Blue (DMMB).

Design of two series of 1:1 cocrystals involving 4-amino-5-chloro-2,6-dimethylpyrimidine and carboxylic acids.

Two series of a total of ten cocrystals involving 4-amino-5-chloro-2,6-dimethylpyrimidine with various carboxylic acids have been prepared and characterized by single-crystal X-ray diffraction. The pyrimidine unit used for the cocrystals offers two ring N atoms (positions N1 and N3) as proton-accepting sites. Depending upon the site of protonation, two types of cations are possible [Rajam et al.

Cation tautomerism, twinning and disorder in the triclinic and monoclinic forms of 4-amino-5-chloro-2,6-dimethylpyrimidinium 5-chloro-2-hydroxybenzoate and a new disordered refinement of 2-amino-4,6-dimethoxypyrimidin-1-ium thiophene-2-carboxylate.

Pyrimidines are important compounds in biology and medicine, and the aminopyrimidine fragment can be identified in three of the four bases in DNA. The targeted drug action of pharmaceuticals containing this functionality is likely to depend heavily on molecular recognition processes involving hydrogen bonding. Crystallization of an equimolar mixture of 4-amino-5-chloro-2,6-dimethylpyrimidine and 5-chloro-2-hydroxybenzoic acid yielded two forms of the 1:1 salt, CHClN·CHClO, each containing a different tautomeric form of the cation.

Crystal structure of 4-amino-5-chloro-2,6-di-methyl-pyrimidinium thio-phene-2,5-di-carboxyl-ate.

In the title salt, C6H9ClN3 (+)·C6H3O4S(-), the cations and anions are linked via O-H⋯O and N-H⋯O hydrogen bonds, forming R 6 (6)(37) ring motifs that are inter-connected with each other, producing sheets. Separate parallel inversion-related sheets are linked through N-H⋯N and π-π stacking inter-actions [centroid-centroid distance = 3.5414 (13) Å], forming double layers parallel to (101).