A comparative study on solubility improvement of tetracycline and dexamethasone by poly(propylene imine) and polyamidoamine dendrimers: An insight into cytotoxicity and cell proliferation

Many of new chemical discovered in pharmaceutical industry are hydrophobic compounds. Various techniques have been used to overcome solubility problems of hydrophobic drugs in aqueous media. In the meantime, dendrimers have been considered for sustainability, nanoscale size, high carry capacity, tunable terminal functional groups in terms of drug delivery and solubility. In this work, we have synthesized poly(propylene imine) (PPI) dendrimer up to fifth generation using reduction of nitrile groups after Michael addition and also, polyamidoamine (PAMAM) dendrimer up to fourth generation using Michael addition and amidation reactions. fourth and fifth generations of PPI dendrimer and fourth and third generations of PAMAM dendrimer in different concentrations were used to evaluate the solubility of two hydrophobic drugs (tetracycline and dexamethasone). Furthermore, cytotoxicity of dendrimers and dendrimers/drugs hybrids was studied. The results showed that with increasing concentrations and also the generation of dendrimers, the solubility of these two hydrophobic drugs was increased. Cytotoxicity study through MTT assay against Osteoblast-like cell line (MG-63 cells) showed that dendrimers were relatively cytotoxic where adding dexamethasone caused higher cytotoxicity. However, tetracycline showed no significant effect on cytotoxicity whereas prevented cell proliferation.

Composite electrospun nanofibers of reduced graphene oxide grafted with poly(3-dodecylthiophene) and poly(3-thiophene ethanol) and blended with polycaprolactone

In this paper, an effective method was employed for preparation of nanofibers using conducting polymer-functionalized reduced graphene oxide (rGO). First, graphene oxide (GO) was obtained from graphite by Hommer method. GO was reduced to rGO by NaBH₄ and covalently functionalized with a 3-thiophene acetic acid (TAA) by an esterification reaction to reach 3-thiophene acetic acid-functionalized reduced graphene oxide macromonomer (rGO-f-TAAM). Afterward, rGO-f-TAAM was copolymerized with 3-dodecylthiophene (3DDT) and 3-thiophene ethanol (3TEt) to yield rGO-f-TAA-co-PDDT (rGO-g-PDDT) and rGO-f-TAA-co-P3TEt (rGO-g-PTEt), which were confirmed by Fourier transform infrared spectra. The grafted materials depicted better electrochemical properties and superior solubilities in organic solvents compared to GO and rGO. The soluble rGO-g-PDDT and rGO-g-PTEt composites blended with polycaprolactone were fabricated by electrospinning, and then cytotoxicity, hydrophilicity, biodegradability and mechanical properties were investigated. The grafted rGO composites exhibited a good electroactivity behavior, mainly because of the enhanced electrochemical performance. The electrospun nanofibers underwent degradation about 7 wt% after 40 days, and the fabricated scaffolds were not able to induce cytotoxicity in mouse osteoblast MC3T3-E1 cells. The soluble conducting composites developed in this study are utilizable in the fabrication of nanofibers with tissue engineering application.