Poly adsorbed lipase

Enzyme activity for the polymerization of lactones was improved by the immobilization on Celite [93]. Immobilized lipase PF adsorbed on a Celite showed much higher catalytic activity than that before the immobilization. The catalytic activity was further enhanced by the addition of a sugar or poly(ethylene glycol) in the immobilization. Surfactant-coated lipase efficiently polymerized the ring-opening polymerization of lactones in organic solvents [94]. 

Although there are notable exceptions as given below, the most common lipase-catalyst used for polyester synthesis is Candida antarctica lipase B (CALB) (please refer to Chapter 14 for more information on the structure and reaction mechanisms of CALB). The immobilized CALB catalyst that has been primarily used is Novozym 435, manufactured by Novozymes (Bagsvaerd, Denmark). Novozym 435 consists of CALB physically adsorbed within the macroporous resin Lewatit VPOC 1600 (poly[methyl methacrylate-co-butyl methacrylate], supplied by Bayer) (please refer to Chapter 3 for more information on Novozym 435). 

Novozym 435 is already a famous biocomposite containing Candida antarctica lipase B (CAL-B) as the bioactive part. Novozym 435 is commercially available immobilized enzyme with CAL-B physically adsorbed on a macroporous resin of poly(methylmethacrylate) [82]. The enzyme versatility and the substrate affinity recommended Novozym 435 for many applications, including the biomass valorization. An example is the production of the fatty acid esters used as emollient in the cosmetic industry (ex. myristyl myristate) [83,84],... 

Poly(acrylic acid) (PAA) was grafted onto the ultra-fine cellulose fiber surfaces via ceric ion initiation (Scheme 5). The carboxylic acid concentration could be controlled by varying monomer AA and/or ceric ion concentrations, and was determined by NaOH-HCl titration using phenophthlein as the indicator. Unless otherwise indicated, fibers with 3.6 mmol of COOH per g cellulose (lAA]/[Ce(IV)]-30) were used for enzyme adsorption and assay. The PAA activated cellulose fibers were immersed in 1.0 mg/ml lipase solution (pH 7.0) at room temperature for 24 hrs. The lipase adsorbed cellulose fibers were rinsed by pH 7 buffer and deionized water to remove loose lipase, then dried under vacuum at room temperature for 12 hrs. 

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