A quantitative x-ray detection system for gold nanoparticle tumour biomarkers

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Medical Imaging

Background:

• X-ray fluorescence (XRF) is established for elemental analysis in biological samples.
• Functionalized nanoparticles offer potential as contrast agents and disease markers.
• Current imaging methods struggle to detect small clusters of cancer cells.

Purpose of the Study:

• To develop and validate a novel XRF approach for detecting and quantifying heavy nanoparticles (e.g., gold) in biological tissues.
• To assess the system's sensitivity and accuracy for nanoparticle concentrations relevant to tumour detection.
• To explore the potential clinical applicability of the developed system for cancer imaging and therapy.

Main Methods:

• Utilized an energy-resolving silicon drift detector with high spectral resolution for XRF measurements.
• Performed synchrotron measurements to establish a calibration curve for gold nanoparticle (GNP) concentration.
• Validated the system using a bench-top X-ray source suitable for potential clinical use.

Main Results:

• Demonstrated a linear relationship between fluorescence intensity and GNP concentration down to 0.005 mgAu ml(-1).
• Achieved a detection limit of 0.005 mgAu ml(-1) for gold nanoparticles.
• Confirmed that a bench-top source maintains the system's detection limit and accuracy.

Conclusions:

• The novel XRF system exhibits high sensitivity and accuracy for quantifying gold nanoparticles in tissues.
• The technology holds potential for in vivo tumour uptake measurement, particularly in shallow sites and small animals.
• The system could enhance early cancer detection by identifying small infiltrating cancer cell clusters and inform cancer therapy.