Activity and Lifetime of Urease Immobilized Using Layer-by-Layer Nano Self-Assembly on Silicon Microchannels

Enzyme co-immobilization: Always the biocatalyst designers' choice…or not?

“…For example, it has been recently published that immobilized ficin utilized in milk clotting has optimal activity when used at maximum loading, while poorly loaded biocatalysts were unable to produce milk coagulation (Siar et al, 2020). This competition in the loading of one enzyme with the loading of the other coimmobilized enzymes may be solved if using multilayer enzyme biocatalysts, where one enzyme is immobilized on an enzyme layer previously immobilized on the support (Deng et al, 2010;Forrest et al, 2005Forrest et al, , 2007Güleç et al, 2010;Gutiérrez et al, 2011;Ondul et al, 2012;Virgen-Ortíz et al, 2017a;Wong et al, 2013) (Figure 9). Using non-porous supports, there are no limits to the number of enzyme layers (that way, many different enzymes may be co-immobilized using this strategy) (Figure 9).…”

Micropatterned Multienzyme Devices with Adjustable Amounts of Immobilized Enzymes

“…BPEI is used because it has shown good adhesion on different surfaces 54,55 and improved properties of enzyme films adsorbed subsequently. 50 The layer thickness of the continuous [(BPEI/ PSS) 2.5 ] film turned out to be sufficient for later LbL formation with enzymes and was not optimized further. The microchannels are formed by a micropatterned PDMS stamp that is pressed on the substrate; after the PE multilayer films were built by sucking material solutions and rinsing solutions through the channels, the PDMS stamp was removed and the resulting patterns were investigated.…”

“…Micropatterned PE multilayer films have been prepared on a continuous [(BPEI/PSS) 2.5 ] precursor layer that provided a highly charged surface for the subsequent adsorption of functional PE multilayer films inside the microchannels. BPEI is used because it has shown good adhesion on different surfaces , and improved properties of enzyme films adsorbed subsequently . The layer thickness of the continuous [(BPEI/PSS) 2.5 ] film turned out to be sufficient for later LbL formation with enzymes and was not optimized further.…”

“…44−46 In contrast, the modification of channel walls inside microfluidic devices with PE multilayer films is used with a broader scope with the aims of controlling electroosmotic flow inside the channels, 47 reducing protein adsorption, 48 and forming microreactors. 49,50 In these examples, only one kind of PE multilayer film was prepared in the different microchannels.…”

“…A straightforward approach to creating micropatterned PE multilayer films, which is also capable of the parallel formation of different micropatterned films, is to perform layer-by-layer assembly inside microchannels that are removed after preparation. This method has been demonstrated in only a few examples. − In contrast, the modification of channel walls inside microfluidic devices with PE multilayer films is used with a broader scope with the aims of controlling electroosmotic flow inside the channels, reducing protein adsorption, and forming microreactors. , In these examples, only one kind of PE multilayer film was prepared in the different microchannels.…”