Table 2.

Some examples of surface-coated magnetic nanoparticles as support materials for enzyme immobilization and their applications.

Magnetic nanocarrier	Enzyme	Functional reagent	Improved properties	Application	References
MNPs	Pseudomonas fluorescens lipase	Co2+	Immobilized lipase possessed 95% conversion efficiency to synthesize biodiesel from waste cooking oil. Excellent operational performance retained higher than 80% of biodiesel yield after 10 repeated conversion cycles.	Biodiesel production	[102]
Fe3O4-NH2@MIL-101(Cr)	Laccase from white rot fungi	MIL-101	High recovered activity, and better endurance to low pH and elevated temperature regimes. Excellent storage stability retaining over 85% of its original bioactivity after storage of 28 days. At an extreme temperature of 85 °C, Fe3O4-NH2@MIL-101(Cr) bound biocatalyst presented about 50% of the remaining activity even after heating for 6 h. Rapid removal of 2,4-dichlorophenol, reaching the removal efficiency to 87%.	Removal of phenolic compounds	[119]
Agarose-coupled novel MNPs	β-glucosidase from sweet almond	Co2+	Immobilized bioconjugate displayed high operational and thermal stability, and preserved over 90% of its preliminary activity after repeatedly using for 15 runs.	Production of aromatic compounds Ethanol from cellulosic agricultural residues	[101]
MNPs-functionalized graphene oxide composites	Lipase B from Candida antarctica	Hyaluronic acid	As compared to the free enzyme, the storage stability of lipase-GO-MNPs was substantially improved. GO-MNPs immobilized lipase showed activity at elevated temperatures retaining over 90% of its recovered activity at 60 °C, whereas the free enzyme retained only 45% of its activity under the same temperature conditions.	Biodiesel production, pharmaceuticals and cosmetic industry	[82]
MNPs	Porcine pancreatic lipase and penicillin G acylase	Cellulose	Improved catalytic activity and stability of immobilized enzymes. Easy separation of immobilized enzymes from the reaction system.	Enzyme immobilization	[120]
MNPs	β-agarase	Tannic acid	Immobilized β-agarase, exhibited greater pH and thermal resistance as well as appreciable recycling ability compared with the free counterpart. The immobilized β-agarase-TA-MNPs system was applied to prepare neoagaro-oligosaccharides with varying degrees of polymerization and antioxidant activities	Preparation of bioactive neoagaro-oligosaccharide	[93]
Trichlorotriazine-functionalized MNPs	Pectinase	Polyethylene glycol	Immobilized enzyme presented improved satisfactory operational stability, improved catalytic efficiency, and easily recyclability in multiple cycles. Augmented pH and thermal stability profile than the free enzyme. Retained up to 94% and 55% of its actual activity after storage for 125 days at 25 °C, and 10 repeated catalytic runs, respectively. A prominent reduction in turbidity of pineapple juice (up to 59%) after treatment with the immobilized enzyme.	Fruit juice clarification	[65]
Fe3O4@MIL-100(Fe)	Candida rugosa lipase	MIL-100(Fe)	Immobilized nanobiocatalytic system retained more than 65% of its original activity at 65 °C for the hydrolysis of olive oil in 6 h. It retained over 60% of residual activity still after 10 repeated catalytic runs. Presented a significant improvement in biocatalytic activities at broader temperature and pH ranges than that to the free enzyme.	Transesterification and synthesis of esters	[117]
MNPs	Cholesterol oxidase	Silica	In contrast to the soluble enzyme, the covalent immobilization of biocatalyst was able to retain about 50% of its activity.	Development of biosensing components	[121]
MNPs	Glucose oxidase	Silica	Immobilized bioconjugate preparation maintained over 95% and 90% of its original activity after storage for 45 days, and 12 consecutive reaction cycles. Substantial improvements in thermal stability profiles were also recorded at high temperatures up to 80 °C. Moreover, the immobilized biocatalyst was less likely to be affected by alterations in pH values	Biomedical applications	[33]
MNPs	Phospholipase D	Silica	Increased tolerance of immobilized enzyme to high temperature. Catalytic activity of the immobilized biocatalyst retained to be 40% after eight recycles.	Synthesis of functional phosphatidylserine	[122]
MNPs film	Horseradish peroxidase from horseradish cv. Balady	Polymethyl methacrylate	Excellent reusability retaining 78.5% of its initial activity after 10 repeated cycles. High stability of the immobilized HRP against metal ions, a high urea concentration, isopropanol, and Triton X-100. Efficient removal of phenol in the presence of hydrogen peroxide.	Removal of wastewater aromatic pollutants	[123]
Fe3O4–graphene nanocomposite	Trametes Versicolor laccase	APTES	Stability and activity of the immobilized nanobiocatalyst was markedly increased than that to free laccase. Retained about 70% of its relative activity after incubating at 55 °C for 2 h, while only 48% of activity was recorded by the free laccase under identical time duration. Nanobioconjugate preserved higher than 85% of its activity after 20 days of storage and possessed satisfactory recycling efficiency exhibiting 85% of its original activity after eight repeated cycles.	Green preparation of sulfa drugs	[83]
Biomimetic silica-MNPs hybrid nanocomposite	β-glucuronidase from Patella vulgata limpets	silica	Superior storage, thermal, and operational stability of the enzyme immobilized in the composite material. Different bioconjugates with MNPs and Si maintained 40% of their original activities at a high temperature of 80 °C after 6 h, while the free form of enzyme dropped over 90% of its activity within 10 min.	Pharmaceutical and food industry	[34]
Fe3O4/Ni-BTC	S-adenosylmethionine synthetase from Thermus thermophilus HB27	Citric acid	Iimmobilized enzyme was more stable against temperature variation (by nearly 8-fold in an 80 °C water bath after 2 h) and extreme pH (by nearly 1.3-fold at pH 3). Excellent reusability after immobilization with high efficiency and stability.	Biosynthesis of S-adenosylmethionine	[118]
Amino-functionalized MNPs	Alkaline protease from Bacillus licheniformis	APTES	Excellent operational stability retaining 50.1% of its initial activity after 10 cycles. Efficient catalytic hydrolysis of oat bran into oat polypeptides.	Preparation of oat polypeptides	[124]
Ni2+-functionalized MNPs	Prolidase from Escherichia coli	Silica	Improved activity at elevated temperature of 70 °C and a wider pH range of 5.5 to 10 than that to free counter form. Enhanced stability at storage for 2 months and reusable for over 20 cycles by retaining 80% of its original activity. Degradation efficiency for organophosphorus compounds.	Hydrolysis of organophosphorus compounds	[103]
MNPs	Candida rugosa lipase	Alkyl silane	Increased catalytic activities of lipases after immobilization. Good stability and recycling ability retained 65% of its initial activity after seven repeated cycles.	Enzyme immobilization	[125]
NPs	Horseradish peroxidase from horseradish cv. Balady	Carbon	Enzyme-based novel amperometric electrode	H2O2 sensing	[73]
MNPs	Lipase from Thermomyces lanuginosus	Polydopamine	A broader pH and temperature adaptability as compared to the free enzyme. Improved pH, thermal, and solvent tolerance stabilities compared to the free enzyme.	Biodiesel production, organic synthesis, and environmental protection	[126]
MNPs	Cellulase from Aspergillus fumigatus	–	Immobilized enzyme retained 56.87% of its maximal activity after 6 h of incubation at 60 °C. Efficient hydrolysis of pre-treated rice straw with saccharification efficiency of 52.67%. Reutilization for up to four saccharification cycles with retention of 50.34% activity.	Enzymatic saccharification of rice straw	[127]
Magnetic carbon nanotubes	Glucoamylase from Aspergillus niger	Poly(amidoamine)	superior stability and reusability, without compromising the substrate specificity of free glucoamylase	Starch processing and glucose production	[128]
Metallic nanomagnets	α-chymotrypsin, lipase B, and β-glucosidase	Carbon	Immobilized bioconjugate preparations showed good stability and catalytic performance and could be recyclable from milliliter to liter volumes in short recycling durations.	Analytical immunoprecipitation and cell separation	[72]
MNPs with long alkyl chains	Candida rugosa lipase	poly- N,N diethylaminoethyl-acrylamide	Nanoimmobilized biocatalytic system with the longest alkyl chains presented superior tolerance to high temperature (ranging from 25 to 70 °C) than that to the free form of lipase. It also showed good recyclability in four successive cycles and conveniently recovered by a simple magnetic separation.	Biodiesel production, food processing , cosmetic and pharmaceutical industry	[49]
Divinyl sulfone superparamagnetic nanoparticles	Lipase from Thermomyces lanuginosus	Polyethyleneimine	Good enantioselectivities with high catalytic activities in the reaction medium at pH 7.0. Excellent operational stability in the esterification reaction obtaining up to 61 % conversion after the seventh reaction cycle.	Biodiesel production, food processing , cosmetic and pharmaceutical industry	[129]
Superparamagnetic nanoparticles (Fe3O4)	Lipase from Thermomyces lanuginosus	Polyethylenimine, APTES, and Glutaraldehyde	The SPMN (superparamagnetic nanoparticle) @APTES covalent preparation had around 450 min of half-life time at pH 7.0 and 70 °C while that of the free enzyme was 46 min. The conversion attained was 50% and the enantiomeric excess of the product was 99%.	Recovery of the biocatalyst	[130]
MNPs	Alcohol dehydrogenase	Carboxymethyl dextran	In contrast to the free form of ADH that dropped 70% of its original activity at 20 °C, and complete loss of its activity at 40 °C after 24 h. Nanoimmobilized biocatalyst retained more than 50%, and 75% of its remaining activity at 20 °C and 40 °C, respectively, under the same incubation period of 24 h.	Chemical industries	[48]
Fe3O4/SiO2/NH2	L-asparaginase	APTES, and Glutaraldehyde	ASNases were more stable in a wide range of pH and temperature values under the optimum reaction conditions. High stability at an elevated temperature of 50 °C for 3 h. Free form of enzyme showed only 30% of its original activity after preserving at 4 °C for 1 month, whereas Fe3O4/SiO2/NH2 ASNase preserved above 78.9% of its preliminary activities. Outstanding functioning stability after 17 consecutive batch cycles.	Anti-leukemia chemotherapy	[31]
Fe3O4/SiO2/COOH	L-asparaginase	APTES, and Glutaraldehyde	High stability in a wide range of pH and temperature values. Preservation of 56.5% of its initial activity. Outstanding operational stability in several consecutive cycles.	Anti-leukemia chemotherapy	[31]
Magnetic graphene nanocomposite	Trichoderma reesei cellulase	Chitosan	With regard to the soluble enzyme, the nanobiocatalytic system showed highly enhanced bioactivity and retained over 75% of its actual activity. After the immobilization process, a substantial widening in pH, storage, and thermal stability were obtained. The immobilized cellulolytic enzyme was capable of maintaining a high degree of its original activity after repeatedly using for 8 cycles.	Saccharification of microcrystalline cellulose	[60]
Sebacoyl-modified MNPs	Lipase B from Candida antarctica	Chitosan	High activity up to 10 repeated catalytic cycles under the optimized conditions (n-hexane, vinyl acetate, 45 °C).	Enzymatic Kinetic Resolution of Racemic Heteroarylethanols	[61]
MNPs	β-glucosidase from Thermotoga maritima	Chitin, chitosan, and sodium alginate	Marked reusability of the nanobiocatalytic system in several successive batches for GOS synthesis without a substantial loss of enzyme activity. Immobilized enzyme showed operational stability under varying pH, temperature, storage, and thermal conditions.	Galacto-oligosaccharide production	[63]
Iron oxide magnetic nanocomposite	Manganese peroxidase from Anthracophyllum discolor	Chitosan	The nanobioconjugate preparation retained its activity and demonstrated recycling ability in 5 consecutive reaction cycles.	Decolorization of textile wastewater	[62]
Fe3O4@SiO2_EDTA-TMS	Laccase	EDTA-Cu (II)	Good operational stability of the immobilized enzyme presenting 73% of its initial activity after five sequential reactive cycles. Successfully applied to the degradation of Indigo Carmine dye	Biocatalysis and biosensors	[131]
MNPs	Tyrosine	Tannic acid	Enzymatic digestion of bovine serum albumin	Protein digestion	[94]
MNPs	Tyrosine	Gallic acid	Immobilized trypsin presented high stability and retained high enzyme relative activity in alkaline pH conditions (pH range of 6 to 10.5) and a temperature range of 45 to 55 °C. It also showed appreciable storage stability retaining over 90% of its original activity after storage for 4 months at 4 °C. After 8 continuous reuse times, the activity of the immobilized enzyme was found to 54.5% of its primary activity.	Diagnostics, pharmaceuticals, food, and waste treatments	[98]
MNPs	Candida rugosa lipase	Gallic acid	Improved esterification activity. Surfactant-coated forms of the magnetic nanobiocatalyst preserved good catalytic activity after seven consecutive reuse cycles.	Production of multicycle ethyl isovalerate	[96]
Fe3O4@silica yolk-shell nanospheres	Catalase from bovine liver	TMOS, APTES	Enhanced recycling efficiency and high resistance to heat, proteolytic agent, and denaturants.	Enzyme shielding	[132]
Fe3+-TA@ Fe3O4/SiO2-catalase	Catalase from bovine liver	TMOS, APTES	Improved stability and efficient recycling ability	Shielding effect to protect enzymes from thermal, biological, and chemical degradation	[133]
Fe3O4@mSiO2	Nitrile hydratase	Glutaraldehyde	Improved pH, thermal, mechanical and storage stability	Catalysis production of nicotinamide	[134]
CA-Fe3O4 NPs	Lipase	Citric acid	Excellent long-term storage stability and increased activity at high temperature and pH	Enzyme immobilization	[4]

MNPs—Magnetic nanoparticles; TMOS— Tetramethyl orthosilicate.