Laser speckle particle sizer (SPARSE) informs the size distribution of tissue granularities

Area of Science:

• Biomedical Optics
• Nanotechnology
• Biomaterials Science

Background:

• Tissues and biomaterials contain diverse particles (cells, organelles, fibers) with sizes ranging from nano- to micrometers.
• Pathological conditions often alter the size distribution of these particles, making quantification challenging.
• Existing methods struggle to measure the wide continuum of particle sizes in intact biological samples.

Purpose of the Study:

• To introduce a noncontact optical technique for particle sizing across a broad size range (10 nm to 10 µm).
• To enable particle size quantification in intact biofluids and tissues without prior knowledge of refractive indices or concentrations.
• To demonstrate the capability of mapping particle size distribution in complex biological samples like breast tissue.

Main Methods:

• Development of laser Speckle PARticle SizEr (SPARSE), a noncontact optical technique.
• Analysis of spatiotemporal attributes of polarized laser speckle back-scattered from samples.
• Application of beam scanning for high-resolution mapping of particle size distribution.

Main Results:

• SPARSE effectively quantifies average particle sizes in milk, blood, and intact tissue.
• The technique operates over a 10 nm to 10 µm particle size range.
• High-resolution mapping (~100 µm) of particle size distribution in benign and malignant breast tissues was achieved, correlating with histopathological features.

Conclusions:

• SPARSE is a novel, noncontact optical method for particle sizing in intact biomaterials and tissues.
• The technique accurately measures particle sizes across a wide nano- to micrometer range.
• SPARSE has significant potential for applications in nanomedicine, diagnostics, and biotechnology.