a Dipartimento di Ingegneria Chimica, dei Materiali e della Produzione Industriale - Università degli Studi di Napoli Federico II, P.le
V. Tecchio 80, 80125 Napoli, Italy
b Istituto di Ricerche sulla Combustione - Consiglio Nazionale delle Ricerche, P.le V. Tecchio 80, 80125 Napoli, Italy
c Dipartimento di Biologia - Università degli Studi di Napoli Federico II, Via Cintia – Complesso Monte Sant’Angelo, 80125 Napoli,
Italy
d Instituto de Catálisis y Petrolquímica - Consejo Superior de Investigaciones Cíentificas, Cantoblanco, 28049 Madrid, Spain
CO2 absorption into aqueous solutions promoted by the enzyme carbonic anhydrase (CA) is a potential postcombustion
CO2 capture process. Carbonic anhydrase (EC 4.2.1.1) catalyzes the CO2 hydration with large
turnover numbers. The work is aimed at the development of CA-based biocatalysts using the technique of
magnetic Cross-Linked Enzyme Aggregates (CLEAs) on bovine carbonic anhydrase (bCA) as model enzyme
and magnetic nanoparticles (NPs). CLEAs were produced by glutaraldehyde cross-linking of precipitated
bCA/NPs aggregates. The optimum conditions of the immobilization procedure were assessed in terms of
type of precipitating agent, concentration of glutaraldehyde, cross linking operating conditions, and
concentration of magnetic NPs. The optimization was carried out with respect to the maximum immobilization
yield and to the CLEA activity. The maximum immobilization yield was about 90% and the maximum activity
(1268 WAU/mgCLEA) was measured for CLEAs prepared with 100 mM glutaraldehyde at 4°C, after 16 h
crosslinking and 0.5 gNPs/gbCA. Morphological analysis of CLEAs prepared under different conditions was
carried out through optical microscopy. Vigorous stirring during precipitation step provided reduction of
aggregates size that was slightly modified by Magnetic field separation. Moreover, possible detrimental effect
of large NPs concentration on CLEA activity was suggested by the morphological analysis.
