**5. Conclusions**

*Applied Surface Science*

production of functional foods.

of antioxidant peptides derived from bovine casein [5]. The casein was hydrolyzed using the magnetic bio-derivative, uncovering its peptides that were sequenced and had antioxidant properties tested through 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging and hydrogen peroxide scavenging assays. After being reused for five times, the magnetic bioderivative was able to maintain more than 74% of the initial activity. Hydrolyzed casein presented similar peptide when used; the free and immobilized enzyme and prevalent peptides could be sequenced. When comparing the reactive oxygen species (ROS) scavenging activity, the hydrolysates presented 2.5 times more than nonhydrolyzed casein, which allows the use of an immobilized protease to obtain natural ingredients derived from casein attractive, indicating potential use in the

**4.3 Synthesis and characterization of magnetized Dacron-heparin composite** 

The focus of this work was to produce a Dacron magnetic composite with heparin (mDAC-HEP) for the use in the purification of antithrombin from human plasma [21]. To obtain mDAC-HEP, heparin was activated by carbodiimide and N-hydroxysuccinimide, allowing covalent attachment. Purified antithrombin was released from the magnetic bio-derivative using solutions with increasing ionic strength (NaCl). The affinity properties of mDAC-HEP after 2 years of storage were preserved, and the magnetic bio-derivative was able to be reused for at least tenfold. The presence of the expected antithrombin size (58 kDa) was revealed in the bands by electrophoresis of the eluates. The composite synthesis was considered easy,

**employed for antithrombin affinity purification**

low-cost, magnet-based affinity purification steps, and reusable.

**diatomaceous earth nanoparticles**

different origins and other biomolecules.

**4.4 High sucrolytic activity by invertase immobilized onto magnetic** 

The purpose of this work was to produce magnetic diatomaceous earth nanopar-

ticles for invertase immobilization (mDE-APTES-invertase) using an easy and low-cost method that could offer high sucrolytic activity [22]. To obtain the results of high residual specific activity (92.5%), an experimental design was made with the objective of achieving the best immobilization conditions. This activity was able to be 2.42 times higher than other derivatives reported in the literature. The thermal and storage stability of the immobilized invertase was verified, and after 120 days of storage, the enzymatic derivative retained 80% of the activity, whereas the free enzyme lost practically all the activity. After ten reuses mDE-APTES-invertase retained 60% of residual activity. Considering the ease of obtaining the matrix and its efficiency, this nanocomposite proves promising to immobilize invertase from

**4.5 Magnetic** *Parkia pendula* **seed gum as a matrix for concanavalin A lectin** 

The main objective of this work was to obtain a magnetic matrix with *Parkia pendula* seed gum to covalently immobilize concanavalin A [20]. The application of this magnetic composite was to obtain glycoconjugates through affinity purification. The obtained gum in the process was magnetized and activated with NaIO4. Concanavalin A immobilized on the magnetic composite was used for the recognition of bovine serum fetuin glycoprotein. A glucose solution (300 mM) was used to carry out the election of the fetuin, and confirmation was made via SDS-PAGE.

**immobilization and its application in affinity purification**

**40**

This chapter has gathered primary and interesting information about immobilization of biomolecules, how to choose the best immobilization methodology, the support for the immobilization, and, among the magnetic materials, why iron oxide particles are highly used as a matrix to immobilization. Several physicochemical techniques were mentioned and described highlighting their features and the main information provided. Lastly, we presented some magnetic bio-derivatives with potential biotechnological applications which could be applied in other areas. So the authors hope that this material has been useful not only for the enzymologists but also to scientists working with applied surface science.
