Sample preservation gel for long-term storage and X-ray CT imaging

Background

The preservation and imaging of delicate biological specimens, particularly in entomology and museum archiving, are critical for advancing morphological and evolutionary studies. Researchers rely on high-fidelity techniques like X-ray computed tomography (CT) and molecular analysis to study these organisms. Consequently, there is a fundamental need for preservation mediums that can simultaneously maintain the structural integrity, hydration, and DNA of soft tissues over time. Specimens must also be securely stabilized during high-resolution imaging to prevent movement and ensure the resulting data accurately reflects the organism’s true anatomy.

Unfortunately, current preservation and mounting approaches suffer from significant limitations. Traditional methods utilizing cotton, rigid holders, or adhesives frequently damage fragile specimens. Liquid ethanol and standard drying techniques often cause soft tissues to shrink, crack, or distort, compromising morphological accuracy and degrading DNA. Furthermore, liquid ethanol is highly flammable, presenting severe logistical risks during storage and shipping. During X-ray CT imaging, conventional liquid mediums introduce severe artifacts—such as air gaps, bubbles, and liquid flow—that drastically reduce image resolution. Existing alternatives, including formalin, vacuum sealing, and standard embedding, consistently fail to balance mechanical stability, chemical safety, and imaging fidelity.

Technology

This gel formulation is designed for the long-term preservation and high-resolution imaging of delicate biological specimens. Composed of carbomer 940, ethanol, water, and optional contrast agents or fixatives, the medium is fabricated through a straightforward neutralization process. The gel physically cushions and immobilizes specimens, preventing mechanical damage and maintaining their natural morphology. Because samples can be stored and imaged directly within the same container, the solution significantly reduces handling. Furthermore, the chemically inert environment supports robust DNA preservation, ensuring specimens remain viable for future molecular analyses.

This technology is highly differentiated by its ability to balance mechanical stability, chemical safety, and imaging fidelity. Unlike standard liquid ethanol storage, which poses flammability risks and allows specimens to shift, this gel immobilizes samples while drastically reducing fire hazards. Traditional mounting or liquid solutions often introduce imaging artifacts like air gaps or liquid flow. In contrast, this gel provides a uniform, low X-ray attenuating medium that minimizes artifacts for high-fidelity X-ray CT scans. It withstands prolonged irradiation without degrading, offering a superior, safer alternative that overcomes the shrinkage and distortion typical of conventional biological archiving.

Benefits

• Mechanically stabilizes and cushions delicate biological specimens to prevent physical damage, shrinkage, and morphological distortion.
• Provides a uniform, low X-ray attenuating medium that minimizes imaging artifacts (such as air gaps and bubbles) for high-fidelity X-ray CT scans.
• Significantly reduces the flammability and safety hazards associated with liquid ethanol, making storage and shipping safer.
• Allows specimens to be imaged directly within their storage containers, minimizing handling and the risk of damaging fragile samples.
• Creates a chemically inert environment that effectively preserves DNA integrity for future molecular analyses.
• Remains highly stable under prolonged X-ray irradiation, ensuring consistent and reproducible data for longitudinal studies.

Applications

• Museum biological specimen archiving
• High-resolution X-ray CT imaging
• Entomological research specimen preservation
• Safe biological specimen shipping
• DNA-preserving biological sample storage

Additional info

This gel formulation consists of 1 wt% carbomer 940, 70–95 wt% ethanol, 30–5 wt% water, and optionally up to 0.1 wt% Lugol’s solution or Bouin’s fixative. Neutralized to a stable state, it suspends and mechanically stabilizes delicate biological specimens. This reduces flammability, preserves DNA, and provides a uniform, low X-ray attenuating medium that minimizes artifacts during high-resolution CT imaging directly within storage containers.of_