Lab Fundamentals & Safety

Main Findings:

• Cross-contamination of biological samples during handling and preparation is a major issue in laboratory setups
• Sample carryover residue in pipette tips contributes greatly to false-positives or false-negatives
• Lubricant-infused pipette tips significantly reduce contamination and carryover
• Innovative surface treatment methods can prevent aerosol formation during pipetting

Relevance to Course: Demonstrates importance of proper pipetting technique and tip selection for preventing contamination in DNA extraction and PCR workflows used throughout the course.

Main Findings:

• Aerosols, suspensions of solid or liquid particles in a gas, are formed in many laboratory activities and are the major contamination source in pipetting
• An aerosol of approximately 15,000 droplets is produced when the last drop of fluid is blown out with moderate force
• Filter tips prevent aerosols from reaching the pipette body
• Releasing the pipette's push button slowly prevents aerosol formation

Relevance to Course: Essential for understanding contamination risks during DNA extraction and PCR setup, where aerosol control is critical for preventing sample cross-contamination.

Key Guidelines:

Filter Tips and Barriers:

• Use sterilized filter tips or positive displacement tips
• Single-use tips with filters are usually recommended as the main strategy to prevent contamination originated from amplicons
• Filters prevent aerosols from reaching the pipette body

Pipetting Techniques:

• Always change the pipette tip after each sample
• Regularly autoclave, or disinfect, the pipette or components that may come into contact with the sample
• Mouth pipetting is prohibited; mechanical pipetting devices must be used
• Pre-wet tips when working with small volumes to improve accuracy

Relevance to Course: Provides evidence-based foundation for laboratory safety protocols used throughout all modules of the course.

Based on the literature reviewed, fundamental laboratory practices should include:

1. Aerosol Control: Slow release of pipette buttons, use of filter tips
2. Contamination Prevention: Single-use tips, regular equipment cleaning, proper disposal
3. Technique Standardization: Consistent pipetting methods, proper tip selection
4. Equipment Maintenance: Regular calibration, cleaning, and replacement of consumables
5. Personal Safety: Appropriate PPE, understanding of chemical hazards
6. Workspace Organization: Designated areas for pre-PCR and post-PCR work

Key guidelines verified on: November 5, 2025

Verification method:

• Peer-reviewed publications and institutional safety guidelines reviewed
• Technical recommendations from equipment manufacturers cross-referenced
• Best practices validated against current biosafety standards

Sources:

• PMC peer-reviewed articles on contamination control
• University biosafety office guidelines (2015-2019)
• Equipment manufacturer technical documentation (Thermo Fisher, Bio-Rad)

Note: These references provide evidence-based foundation for laboratory safety and technique protocols used throughout the course. Students should refer to institution-specific safety guidelines for local requirements.