Chemical Orthogonality in Surface-Patterned Poly(ethylene glycol) Microgels

Area of Science:

• Materials Science
• Surface Chemistry
• Biotechnology

Background:

• Poly(ethylene glycol) (PEG) is widely used for antifouling surfaces to control biomolecule and cell interactions at micro- and nanoscale.
• Existing methods for patterning PEG surfaces often lack the ability to introduce additional functionalities beyond antifouling properties.

Purpose of the Study:

• To develop a method for creating multifunctional PEG-patterned surfaces using electron beam patterning.
• To investigate the induction of secondary chemical functionalities on PEG surfaces orthogonal to initial functionalities.
• To assess the preservation of antifouling properties alongside introduced functionalities.

Main Methods:

• Patterning of monofunctional poly(ethylene glycol) (PEG) thin films using focused electron beams.
• Cross-linking of PEG precursors and grafting of patterned microgels to substrates.
• Exploration of reactivity of biotin-terminated PEG (PEG-B) and hydroxy-terminated PEG (PEG-OH) as a function of electron dose.
• Assessment of resistance to fibronectin adsorption and reactivity with streptavidin (SA) and amine groups.

Main Results:

• Electron beam patterning induces secondary chemical functionalities on PEG surfaces through radiation chemistry, orthogonal to initial functionalities.
• Biotin-terminated PEG (PEG-B) shows reactivity with streptavidin (SA) at low electron doses, which decays at higher doses due to biotin damage.
• Amine reactivity emerges at higher electron doses, originating from the PEG main chain, likely due to the formation of carbonyl and carboxyl groups.
• Patterned PEG microgels maintain antifouling properties, resisting fibronectin adsorption at both low and high electron doses.
• Functional contrast between differentially patterned areas is estimated to be a factor of six or more.

Conclusions:

• Focused electron beam patterning offers a versatile approach to create multifunctional PEG surfaces with tunable chemical properties.
• This technique enables the precise patterning of biospecific functionalities while retaining antifouling characteristics.
• The method is suitable for applications requiring control over protein and cell interactions at micro- and nanoscale levels.