We present work on the synthesis of an improved nanoparticle-containing composite gel for imaging the fine vasculature of biological systems using X-ray techniques. The composite is composed of PbCO3 nanoparticles (LNPs) distributed in an alginate hydrogel to produce a nanocomposite that gels after perfusion into the fine vasculature. PbCO3 is used as the X-ray contrast agent due to its excellent X-ray opacity and low water solubility. LNPs are produced by an arrested precipitation process with capping provided by tetraethylene glycol, which controls nanocrystal growth and also confers water dispersibility to the system. The LNPs are fixed by dispersing within an alginate solution followed by cross-linking of the gel. The LNPs have controllable X-ray contrast by variation of their concentration within the composite structure. Preliminary data and testing using X-ray and micro-CT imaging demonstrates that the LNPs have excellent X-ray contrast comparable to or greater than that of bone. We performed a series of structure and energy calculations on various model metal dication-alginate compositions to gain further insight into the relative structural stabilities of the gels using DFT methods. The characteristics of the developed nanocomposite gel were shown to be improved over that of commercially available Microfil and a previously reported barium sulfate nanocomposite with a similar structure.

MicroCT scan of a mouse femur after 0.4 g/mL LNP perfusion, gelation, and fixation.

X-ray scan of mouse vasculature after 0.4 g/mL LNP perfusion, gelation, and fixation.

Paul Jelliss

Saint Louis University

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