Contents lists available at ScienceDirect Materials Science & Engineering C journal homepage: www.elsevier.com/locate/msec Immobilization of cellulase on iron tolerant Pseudomonas stutzeri biosynthesized photocatalytically active magnetic nanoparticles for increased thermal stability Megha P. Desai, Kiran D. Pawar ⁎ School of Nanoscience and Biotechnology, Shivaji University, Kolhapur, Maharashtra, India ARTICLE INFO Keywords: Iron tolerance Magnetic nanoparticle Superparamagnetic Cellulase Immobilization Photocatalytic ABSTRACT Bacteria mediated synthesis of magnetic nanoparticles (MNPs) for biotechnological applications is an important area of nanotechnology. This study demonstrates the use of iron tolerant bacterium for synthesis of MNPs for cellulase immobilization and photocatalytic activity. The enrichment, isolation, screening and molecular iden- tification led to the selection of Pseudomonas stutzeri KDP_M2 with high degree of iron tolerance. The synthesis parameters such as 1 mM ferric quinate, pH 9 and 96 h static incubation were found optimum for maximum yield of 210 mg/L. The characterization using various techniques indicated that MNPs were Hematite (Fe 2 O 3 ) with particle size between 10 and 20 nm. Further, vibrating sample magnetometer and thermogravimetric analyses demonstrated the superparamagnetic nature with high thermal stability. The MNPs were found an excellent support for immobilization of industrially important cellulase with 96.5% binding efficiency. The immobiliza- tion which was confirmed by Fourier transform infrared spectroscopy indicated that immobilization did not reduce the cellulase activity, rather enhanced the thermal stability and operational temperature range of cel- lulase. The immobilized cellulase showed maximum cellulolytic activity at pH 4.6 and retained 80% activity upto 3rd cycle of reuse, therefore, can be utilized repeatedly at acidic conditions.The monitoring the photo- catalytic activity showed rapid degradation of methyl violet and methylene blue within initial 10 min. of re- action. 1. Introduction Magnetic nanoparticles (MNPs) are one of the most sought-after nanomaterials (NMs) for various applications in material science, electronics, optics, magnetism and electrochemistry along with biology, medicine, molecular biology, bioinorganic chemistry, as well as en- vironmental science [1–4]. Among various types of MNPs, iron oxide magnetic nanoparticles (IOMNPs) such as magnetite, hematite, and maghemite have gained a great deal of attention due to their properties like superparamagnetism, small size, high surface area to volume ratio and ease of separation for repeated cycles of uses. These properties together with low toxicity, good biocompatibility and ease of surface functionalization make IOMNPs suitable material for various applica- tions including biomedical applications. In biotechnology and medi- cine, they are used for magnetic separation of biomolecules, magnetic resonance imaging (MRI), tissue repair, drug delivery, hyperthermia treatment of tumor cells, detection of toxins and immunoassays, en- zyme immobilization, protein adsorption, rapid and scalable separation and purification etc. [5,6]. The chemical and physical of methods MNP synthesis are known for being energy intensive, costly and hazardous, therefore, limit the ap- plications of MNPs in the biomedical field. The use of toxic chemicals also exerts harmful effects by polluting the environment. As an alter- native to physical and chemical methods, biological synthesis of MNPs using plant, fungi, bacteria, their enzymes and the metabolite is gaining impetus. It is well established that these biological agents and their metabolite can act as reducing and capping agents, therefore, be used in the biological synthesis of NMs [7–11]. Biological synthesis is ad- vantageous over chemical and physical methods due to its low energy requirement, environmental compatibility, low cost and stabilized na- noparticle synthesis [12]. Among the biological agents, bacteria are considered as potent nanofactories for the synthesis of nanoparticles by the eco-friendly and safe approach. Bacteria-mediated MNPs synthesis is less toxic, biocompatible and inexpensive compared to other physical and biological methods [13]. It is known that bacteria can synthesize MNPs by the biological https://doi.org/10.1016/j.msec.2019.110169 Received 15 February 2019; Received in revised form 1 August 2019; Accepted 5 September 2019 ⁎ Corresponding author. E-mail address: kdp.snst@unishivaji.ac.in (K.D. Pawar). Materials Science & Engineering C 106 (2020) 110169 Available online 06 September 2019 0928-4931/ © 2019 Elsevier B.V. All rights reserved. T