Development of a dynamic delivery method for in vitro bioassays

Area of Science:

• Environmental Chemistry
• Biochemistry
• Materials Science

Background:

• In vitro assays for hydrophobic chemicals face challenges due to low aqueous solubility and reduced bioavailability in dense bio-suspensions.
• Poly(dimethylsiloxane) (PDMS) offers a potential solution due to its biocompatibility and partitioning capabilities.

Purpose of the Study:

• To develop and validate a dynamic dosing system using PDMS for delivering hydrophobic chemicals (polycyclic aromatic hydrocarbons - PAHs) to model bio-suspensions.
• To assess the efficiency of PDMS in overcoming bioavailability limitations for hydrophobic pollutants in complex biological matrices.

Main Methods:

• PDMS sheets were loaded with five PAHs and immersed in model bio-suspensions (chromatophores or liposomes).
• Partition coefficients, desorption rate constants, and diffusion resistances were determined.
• PAH release from PDMS was measured and modeled to evaluate mass transfer dynamics.

Main Results:

• The PDMS system demonstrated lower mass transfer resistance for PAH release compared to conventional solutions, enabling efficient delivery to dense bio-suspensions.
• Aqueous diffusion's contribution to mass transfer decreased with increasing PAH hydrophobicity, indicating efficient transport with suspended biomaterial.
• The system proved versatile for both instantaneous and long-term passive dosing applications.

Conclusions:

• PDMS-based dynamic dosing effectively enhances the bioavailability of hydrophobic chemicals in in vitro assays.
• This passive dosing system offers a versatile and efficient method for studying hydrophobic pollutant activity in complex biological environments.
• The technology holds promise for developing rapid, time-dependent bioactivity tests and ensuring consistent dosing for extended studies.