Quantitative analysis of biologic specimens by X-ray scanning analytic microscopy

Area of Science:

• Materials Science
• Biomedical Engineering
• Analytical Chemistry

Background:

• Elemental distribution analysis is crucial for understanding biological processes and material interactions.
• X-ray scanning analytic microscopy (XSAM) offers a method for visualizing elemental composition in specimens.
• Assessing the toxicity of elements, particularly metals, in soft tissues requires accurate quantification.

Purpose of the Study:

• To prepare and utilize standard specimens for quantitative elemental analysis in biological tissues using XSAM.
• To determine the concentrations of elements, including metals, in normal and metal-implanted rat tissues.
• To evaluate the soft tissue toxicity of specific elements based on their concentrations and observed inflammatory responses.

Main Methods:

• Preparation of two types of standard specimens: methylmethacrylate (MMA) resin-based for low concentrations and lithium borate glass-based for higher concentrations.
• Quantitative analysis of phosphorus (P) and calcium (Ca) in normal rat tissues.
• Analysis of dissolved nickel (Ni), iron (Fe), and copper (Cu) concentrations around metal implants in soft tissues.

Main Results:

• Estimated dissolved Fe, Cu, and Ni concentrations from implants were 1000 mM, 40 mM, and 20 mM, respectively.
• High toxicity of Ni and Cu to soft tissue was confirmed at concentrations as low as 10 mM, with Cu toxicity being similar to Ni.
• Iron exhibited low toxicity despite high dissolved concentrations (up to 1000 mM).

Conclusions:

• XSAM is effective for estimating nonmetallic and low-concentration metallic elements dispersed in soft tissue.
• Nickel and copper demonstrate significant soft tissue toxicity at low concentrations, necessitating careful consideration in biomedical applications.
• Iron appears to have a lower toxicity profile compared to nickel and copper in soft tissues, even at elevated concentrations.