Calcium-activated gene transfection from DNA/poly(amic acid-co-imide) complexes

Abstract

In this study, we synthesized a water-soluble poly(amic acid-co-imide) (PA-I) from ethylenediaminetetraacetic dianhydride (EDTA) and 2,2′-(ethylenedioxy)bis(ethylamine) that possesses comparable transfection efficiency to that of polyethylenimine (PEI), when prepared in combination with divalent calcium cations. The polycondensation of monomers afforded poly(amic acid) (PA) precursors, and subsequent thermal imidization resulted in the formation of PA-I. At a polymer/DNA ratio (indicated by the molar ratio of nitrogen in the polymer to phosphate in DNA) of 40, complete retardation of the DNA band was observed by gel electrophoresis, indicating the strong association of DNA with PA-I. A zeta potential of −22 mV was recorded for the PA-I polymer solution, and no apparent cytotoxicity was observed at concentrations up to 500 μg·mL −1 . In the presence of divalent Ca 2+ , the transfection efficiency of PA-I was higher than that of PA, due to the formation of a copolymer/Ca 2+ /DNA polyplex and the reduction in negative charge due to thermal cyclization. Interestingly, a synergistic effect of Ca 2+ and the synthesized copolymer on DNA transfection was observed. The use of Ca 2+ or copolymer alone resulted in unsatisfactory delivery, whereas the formation of three-component polyplexes synergistically increased DNA transfection. Our findings demonstrated that a PA-I/Ca 2+ /DNA polyplex could serve as a promising candidate for gene delivery.

CaCl2-Activated Carbon Nitride: Hierarchically Porous Carbons with Ultrahigh Nitrogen Content for Selective CO2 Adsorption

“…[38][39][40][41][42] CaCl2 activation is advantageous over potassium hydroxide due to its lower relative cost, non-corrosiveness, and favorable stabilizing interactions with nitrogen functionalities similar to those present in carbon nitride. [43][44][45][46] To date, few studies have employed calcium chloride as an activating agent for nitrogen doped carbons, but these limited few have shown increased heteroatom retention and incorporation in the resulting products. 39,42 To our knowledge, CaCl2 has never been applied to chemically activate carbon nitride for creating a porous, nitrogen-doped carbon material.…”