Immobilization of Aspergillus niger lipase on chitosan-coated magnetic nanoparticles using two covalent-binding methods

Aspergillus niger lipase immobilization by covalent binding on chitosan-coated magnetic nanoparticles (CMNP), obtained by one-step co-precipitation, was studied. Hydroxyl and amino groups of support were activated using glycidol and glutaraldehyde, respectively. Fourier transform infrared spectrometry, high-resolution transmission electron microscopy and thermogravimetric analysis confirmed reaction of these coupling agents with the enzyme and achievement of a successful immobilization. The derivatives showed activities of 309.5 ± 2.0 and 266.2 ± 2.8 U (g support)(-1) for the CMNP treated with glutaraldehyde and with glycidol, respectively. Immobilization enhanced the enzyme stability against changes of pH and temperature, compared to free lipase. Furthermore, the kinetic parameters K m and V max were determined for the free and immobilized enzyme. K m value quantified for enzyme immobilized by means of glutaraldehyde was 1.7 times lowers than for free lipase. High storage stability during 50 days was observed in the immobilized derivatives. Finally, immobilized derivatives retained above 80% of their initial activity after 15 hydrolytic cycles. The immobilized enzyme can be applied in various biotechnological processes involving magnetic separation.Fil: Osuna, Yolanda. Universidad Autónoma de Coahuila; MéxicoFil: Sandoval, José. Universidad Autónoma de Coahuila; MéxicoFil: Saade, Hened. Centro de Investigación en Química Aplicada; MéxicoFil: López, Raúl G.. Centro de Investigación en Química Aplicada; MéxicoFil: Martinez, José L.. Universidad Autónoma de Coahuila; MéxicoFil: Colunga, Edith M.. Universidad Autónoma de Coahuila; MéxicoFil: de la Cruz, Gabriela. Universidad Autónoma de Coahuila; MéxicoFil: Segura, Elda P.. Universidad Autónoma de Coahuila; MéxicoFil: Arevalo, Fernando Javier. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zon, María Alicia. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fernandez, Hector. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ilyina, Anna. Universidad Autónoma de Coahuila; Méxic

Effect of Carya illinoinensis, Quercus rubra and Smilax glyciphylla extracts, pectin, and papain on the dental biofilm microorganisms

Context: Dental caries is an infectious disease resulting in destruction of tooth structure by acid-forming bacteria found in dental plaque and intraoral biofilms, which are made up of mixed-species microbial communities, and their uncontrolled outgrowth can lead to oral disease. Aims: To analyze new biological materials (papain, pectin, three plant extracts and their combinations), for prevention, control, and treatment of oral bacteria and biofilm in vitro and in vivo. Methods: Papain, citric pectin, extracts of Carya illinoinensis, Quercus rubra, and Smilax glyciphylla were applied. In vitro test was performed by means of the spectrophotometric assay and CFU evaluation after treatments application. In vivo tests were performed to evaluate the number of microorganisms presented in dental biofilm: before and 1.5 h after brushing with different treatments; after 10 days of brushing with various treatments in 10 groups of patients, signing an informed consent approved by the Institutional Ethics Committee of the Autonomous University of Coahuila. Results: In vitro, the plant extracts inhibited the growth of Streptococcus sp. as well as a mixture of microorganisms that form dental biofilms. Papain activity was inhibited by plant extracts. In vivo, brushing of teeth with selected plant extracts reduced the number of bacteria in the dental plaques. Conclusions: The extracts of Quercus rubra, Carya illinoinensis and Smilax glyciphylla and papain (with or without pectin) had an inhibitory effect on the dental biofilm formation. In vitro test demonstrated the bacteriostatic effect of plant extracts or their mixture