Reversible Molecular Capture and Release in Microfluidics by Host-Guest Interactions in Hydrogel Microdots

Area of Science:

• Supramolecular Chemistry
• Microfluidics
• Materials Science

Background:

• Microfluidic systems are increasingly integrated with hydrogels for selective molecular interactions.
• Hydrogels with high surface area and reactive groups are crucial for these applications.

Purpose of the Study:

• To report the reversible capture and release of molecules using host-guest interactions within hydrogel dots in a microfluidic device.
• To translate supramolecular chemistry principles to microscale continuous flow conditions.

Main Methods:

• Fabrication of polyacrylamide (PAAm) hydrogel arrays grafted with β-cyclodextrin (β-CD) modified poly(2-methyl-2-oxazoline) (CD-PMOXA) chains via photopolymerization.
• Integration of hydrogel arrays into a polydimethylsiloxane (PDMS)-on-glass microfluidic chip.
• Confirmation of β-CD/adamantane (β-CD/Ada) host-guest complex using 2D NOESY NMR.

Main Results:

• Successfully captured Ada-modified molecules via host-guest interactions between CD-PMOXA chains and guest molecules.
• Achieved release of captured molecules by perfusing free β-CD with higher affinity.
• Demonstrated reproducible capture and release of small (Ada-FITC) and large (Ada-PMOXA-Cy5) molecules over three cycles with high release ratios (up to 92%).

Conclusions:

• The developed hydrogel system exhibits stability in microfluidics for reproducible molecular capture and release.
• This approach offers potential for future applications requiring selective molecular manipulation at the microscale.