Magneto-Responsive Hydrogels: Preparation, Characterization, Biotechnological and Environmental Applications

Frachini, Emilli C. G.; Petri, Denise F. S.

doi:10.21577/0103-5053.20190074

Emilli C. G. Frachini

Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, 05508-000 São Paulo-SP, Brazil

Emilli Caroline Garcia Frachini received her master’s degree in Chemistry in 2018 at the Universidade Estadual de Londrina, UEL (Brazil). She worked in environmental risk assessment in watersheds, as Doce River (Minas Gerais) and Tibagi River (Paraná). Since July 2018, she is a PhD student in Prof Denise Petri’s group, at the University of São Paulo, Brazil. Her current research focuses on the synthesis of magneto-responsive hydrogels for drug delivery and tissue engineering.

https://orcid.org/0000-0002-6147-183X

Denise F. S. Petri ^**e-mail: dfsp@iq.usp.br

Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, 05508-000 São Paulo-SP, Brazil

Denise Freitas Siqueira Petri is Professor of Chemistry at the Universidade de São Paulo, USP (Brazil). She received her master’s (1990) and PhD (1992) degrees at Universidade Estadual de Campinas, UNICAMP (Brazil). She was postdoc at the Max Planck Institute for Polymer Chemistry, Mainz, Germany (1993-1995) and at the Polymer Institut, Universitaet Karlsruhe, Germany (1996-1997). She was appointed as Professor at the University of São Paulo in 1998. Since 2014, she is a Full Professor at the University of São Paulo. From March 2014 to February 2018, she was the coordinator of the IQUSP Professional Master’s Program in Chemistry and Biochemistry. Her interests are biopolymers at surfaces and interfaces and their interaction with nanoparticles, pollutants, proteins and cells.

https://orcid.org/0000-0003-4814-8357

*e-mail: dfsp@iq.usp.br

Emilli Caroline Garcia Frachini

received her master’s degree in Chemistry in 2018 at the Universidade Estadual de Londrina, UEL (Brazil). She worked in environmental risk assessment in watersheds, as Doce River (Minas Gerais) and Tibagi River (Paraná). Since July 2018, she is a PhD student in Prof Denise Petri’s group, at the University of São Paulo, Brazil. Her current research focuses on the synthesis of magneto-responsive hydrogels for drug delivery and tissue engineering.

Denise Freitas Siqueira Petri

is Professor of Chemistry at the Universidade de São Paulo, USP (Brazil). She received her master’s (1990) and PhD (1992) degrees at Universidade Estadual de Campinas, UNICAMP (Brazil). She was postdoc at the Max Planck Institute for Polymer Chemistry, Mainz, Germany (1993-1995) and at the Polymer Institut, Universitaet Karlsruhe, Germany (1996-1997). She was appointed as Professor at the University of São Paulo in 1998. Since 2014, she is a Full Professor at the University of São Paulo. From March 2014 to February 2018, she was the coordinator of the IQUSP Professional Master’s Program in Chemistry and Biochemistry. Her interests are biopolymers at surfaces and interfaces and their interaction with nanoparticles, pollutants, proteins and cells.

Hydrogel	Synthesis route	Drug	Stimulus	Reference
Hemicellulose gel	in situ co-precipitation	BSA	permanent magnet	⁸⁶86 Zhao, W.; Odelius, K.; Edlund, U.; Zhao, C.; Albertsson, A. C.; Biomacromolecules 2015, 16, 2522.
CS	in situ co-precipitation	adriamycin/rifampicin	permanent magnets, 0.4 T	⁹⁷97 Wang, Y.; Li, B.; Xu, F.; Han, Z.; Wei, D.; Jia, D.; Zhou, Y.; Biomacromolecules 2018, 19, 3351.
Alginate bead	in situ co-precipitation	dopamine	Nd magnet discs (1 cm diameter and 1.5 mm thick), 0.4 T	⁹⁸98 Kondaveeti, S.; Cornejo, D. R.; Petri, D. F. S.; Colloids Surf. , B 2016, 138, 94.
Transdermal patches alginate/xanthan	in situ co-precipitation	levodopa	Nd magnet discs (1 cm diameter and 1.5 mm thick), 0.4 T	⁹⁹99 Kondaveeti, S.; Semeano, A. T. S.; Cornejo, D. R.; Ulrich, H.; Petri, D. F. S.; Colloids Surf. , B 2018, 167, 415.
Beads of k-carrageenan/CMC-CS	in situ co-precipitation	diclofenac sodium	alternating EMF apparatus with frequency of 350 kHz, 100 and 300 G	¹⁰⁰100 Mahdavinia, G. R.; Etemadi, H.; Soleymani, F.; Carbohydr. Polym. 2015, 128, 112.
CMC/acrylamide	blending	diclofenac sodium	100 and 300 G	¹⁰¹101 Mahdavinia, G. R.; Afzali, A.; Etemadi, H.; Hoseinzadeh, H.; Nanomed. Res. J. 2017, 2, 111.
CS/GU/MA gel	in situ co-precipitation	curcumin	0.35 T	⁷⁸78 Paulino, A. T.; Pereira, A. G.; Fajardo, A. R.; Erickson, K.; Kipper, M. J.; Muniz, E. C.; Belfiore, L. A.; Tambourgi, E. B.; Carbohydr. Polym. 2012, 90, 1216.
PVA thin film	in situ co-precipitation	ciprofloxacin	in vitro release experiments under EMF of 75 G	¹⁰²102 Bajpai, A. K.; Gupta, R.; Mater. Sci. Mater. Med. 2011, 22, 357.
Lipid microcapsule	blending	DOX or CF	EMF was applied by magnetic field coils of 2 kHz and 20 mT	¹⁰³103 Bi, H.; Ma, S.; Li, Q.; Han, X.; J. Mater. Chem. B 2016, 4, 3269.
Bead of alginate/CS	in situ co-precipitation	insulin	discs of permanent magnet (NdFeB, 10 × 10 mm)	¹⁰⁴104 Finotelli, P. V.; da Silva, D.; Sola-Penna, M.; Rossi, A. M.; Farina, M.; Andrade, L. R.; Takeuchi, A. Y.; Rocha-Leão, M. H.; Colloids Surf. , B 2010, 81, 206.
Nanoparticle of starch	in situ co-precipitation	cisplatin	in vitro drug delivery, 300 G	¹⁰⁵105 Likhitkar, S.; Bajpai, A. K.; Carbohydr. Polym. 2012, 87, 300.
Transdermal patches of xanthan	blending	amoxicillin	permanent magnets of Nd	¹⁰⁶106 Bueno, P. V.; Hilamatu, K. C.; Carmona-Ribeiro, A. M.; Petri, D. F.; Int. J. Biol. Macromol. 2018, 115, 792.

Scaffold	Cell type	Stimuli	Remark	Reference
Type II collagen	bone marrow derived mesenchymal st	N42 neodymium magnet, diameter of 22 and 25 mm high	EMF was used to guide the scaffold to the exact cartilage defect site remotely	¹²⁴124 Zhang, N.; Lock, J.; Sallee, A.; Liu, H.; ACS Appl. Mater. Interfaces 2015, 7, 20987.
HA/collagen, magnetization ranging from 0.5 to 1.7 emu g^-1	human bone marrow st, in vitro	no EMF	bone graft substitute, good cell adhesion and proliferation	¹²⁵125 Bock, N.; Riminucci, A.; Dionigi, C.; Russo, A.; Tampieri, A.; Landi, E.; Goranov, V. A.; Marcacci, M.; Dediu, V.; Acta Biomater. 2010, 6, 786.
Fibrous PLA/HA electrospun scaffolds, saturation magnetization of 0.049 emu g^-1	bone tissue-lumbar transverse defect of rabbits, in vivo	scaffolds with static magnets distributed along the animal cage, magnetic intensity from 0.05 to 25 mT	accelerated bone tissue regeneration	¹²⁶126 Meng, J.; Xiao, B.; Zhang, Y.; Liu, J.; Xue, H.; Lei, J.; Kong, H.; Huang, Y.; Jin, Z.; Gu, N.; Xu, H.; Sci. Rep. 2013, 3, 2655.
PCL and MNP	mouse calvarium osteoblasts, in vivo and in vitro	neodymium (Nd₂Fe₁₄B) disc magnet (1 mm thick × 15 mm diameter)	activation of integrin signaling pathways and up-regulation of bone morphogenetic protein-2 and phosphorylation of Smad1/5/8; promotion of expression of vascular endothelial growth factor and angiogenin-1 genes and the formation of capillary tubes	¹²⁷127 Yun, H. -M.; Ahn, S. -J.; Park, K. -R.; Kim, M. -J.; Kim, J. -J.; Jin, G. -Z.; Kim, H. -W.; Kim, E. -C.; Biomaterials 2016, 85, 88.
HA doped with Fe²⁺/Fe³⁺ ions and collagen	human osteosarcoma cell, in vitro	static EMF 320 mT	improved cell proliferation compared to the nonmagnetic control scaffold	¹²⁸128 Tampieri, A.; Iafisco, M.; Sandri, M.; Panseri, S.; Cunha, C.; Sprio, S.; Savini, S.; Uhlarz, M.; Hermannsdofer, T.; ACS Appl. Mater. Interfaces 2014, 6, 15697.
Methacrylated chondroitin sulfate enriched with platelet lysate and MNP	osteogenically differentiated adipose-derived stem cells and/or tendon-derived cells, in vitro	static EMF 350 mT	impacted cell morphology and the expression and synthesis of tendon- and bone-like matrix	¹²⁹129 Silva, E. D.; Babo, P. S.; Costa-Almeida, R.; Domingues, R. M. A.; Mendes, B. B.; Paz, E.; Freitas, P.; Rodrigues, M. T.; Granja, P. L.; Gomes, M. E.; Nanomedicine 2018, 14, 2375.
Alginate/MNP	endothelial cells, in vitro	AC magnetic field of 10-15 G	enhanced stimulation of endothelial cells and organization into capillary-like structures	¹³⁰130 Sapir, Y.; Cohen, S.; Friedman, G.; Polyak, B.; Biomaterials 2012, 33, 4100.
Fibrin/Fe₃O₄	cardiac cells, in vitro	oscillating Nd magnet	increase in twitch force of contraction in response to non-contact stretch	¹³¹131 Hogan, M.; Chen, Y. -T.; Kolhatkar, A. G.; Candelari, C. J.; Madala, S.; Lee, T. R.; Birla, R.; ACS Biomater. Sci. Eng. 2016, 2, 1619.
Xanthan and MNP	fibroblast, in vitro	static EMF 400 mT	increase of cell proliferation and influx of Ca²⁺ ions	⁶⁰60 Bueno, V. B.; Silva, A. M.; Barbosa, L. R. S.; Catalani, L. H.; Teixeira-Neto, É.; Cornejo, D. R.; Petri, D. F. S.; Chem. Commun. 2013, 49, 9911.
Xanthan, polypyrrole and MNP	fibroblast, in vitro	static EMF 400 mT	increase of cell proliferation	¹³²132 Bueno, V. B.; Takahashi, S. H.; Catalani, L. H.; de Torresi, S. I. C.; Petri, D. F. S.; Mater. Sci. Eng. , C 2015, 52, 121.
Chitosan/alginate multilayer and MNP	fibroblast, in vitro	no EMF	higher cell proliferation rate	¹³³133 Gil, S.; Silva, J. M.; Mano, J. F.; ACS Biomater. Sci. Eng. 2015, 1, 1016.
Xanthan and MNP	neuronal cells, in vitro	static EMF 400 mT	increased cell proliferation and differentiation to sensorial neurons	⁶⁶66 Glaser, T.; Bueno, V. B.; Cornejo, D. R.; Petri, D. F.; Ulrich, H.; Biomed. Mater. 2015, 10, 045002.
Starch coated MNP and chitosan coated MNP	neuronal cells, in vitro	intermittent 150 mT	starch coated MNP favored Ca²⁺ influx	¹³⁴134 Tay, A.; Kunze, A.; Murray, C.; Di Carlo, D.; ACS Nano 2016, 10, 2331.
Xanthan, alginate and MNP loaded with levodopa	neuronal cells, in vitro	static EMF 400 mT	sustained release of levodopa and differentiation to dopaminergic neurons	⁹⁹99 Kondaveeti, S.; Semeano, A. T. S.; Cornejo, D. R.; Ulrich, H.; Petri, D. F. S.; Colloids Surf. , B 2018, 167, 415.
Xanthan/chitosan	NIH3T3 fibroblast	permanent magnet	cell adhesion and proliferation of NIH3T3 fibroblasts were favored	¹³⁵135 Rao, K. M.; Kumar, A.; Han, S. S.; J. Mater. Sci. Technol. 2018, 34, 1371.
Polycaprolactone	MC3T3-E1	permanent magnet	improved affinity of proteins and cells for the scaffolds	¹³⁶136 Kim, J. J.; Singh, R. K.; Seo, S. J.; Kim, T. H.; Kim, J. H.; Lee, E. J.; Kim, H. W.; RSC Adv. 2014, 4, 17325.

Material	Cell	Therapy	Remark	Reference
PEG-MMA	M059K glioblastoma cells; in vitro	hyperthermia	electromagnetic field induced by a Taylor Winfield induction power supply; solenoid of 15 mm diameter, 297 kHz and 25 kA m^-1	¹⁶¹161 Meenach, S. A.; Hilt, J. Z.; Anderson, K. W.; Acta Biomater. 2010, 6, 1039.
PEG/LA-CS coated on the surface of the biofunctionalized Fe₃O₄	in vitro: K562 cells; in vivo:liver MRI	MRI	in vivo: intravenously injected; rats were exposed to 1.5 T in vitro: MRI was carried out on an AW 4.2 working station	¹⁶⁴164 Song, X.; Luo, X.; Zhang, Q.; Zhu, A.; Ji, L.; Yan, C.; J. Magn. Magn. Mater. 2015, 388, 116.
CS/GP	intraperitoneal injection to bladder, in vivo	drug release; release of BCG	EMF of 4 kG; superior antitumor efficacy	¹⁵⁴154 Zhang, D.; Sun, P.; Li, P.; Xue, A.; Zhang, X.; Zhang, H.; Jin, X.; Biomaterials 2013, 34, 10258.
CS/GP; polyethylenimine-modified super-paramagnetic graphene oxide	in vitro: MCF-7 cells; in vivo: S180 tumor-bearing mice	hyperthermia/release of DOX	EMF 488 kHz, 20 A	¹⁶²162 Zhu, X.; Zhang, H.; Huang, H.; Zhang, Y.; Hou, L.; Zhang, Z.; Nanotechnology 2015, 26, 365103.
CS/PEG	in vitro: L-929 cells MDA-MB-231; in vivo:MDA-MB-231	dual-drug-loaded magnetic hydrogel: DOX/DTX	EMF 19.99 kA m^-1, 282 kHz	¹⁵⁷157 Xie, W.; Gao, Q.; Guo, Z.; Wang, D.; Gao, F.; Wang, X.; Wei, Y.; Zhao, L.; ACS Appl. Mater. Interfaces 2017, 9, 3660.
Dextran-coated SPIONs	a rabbit with VX2 malignant tumor. The tumor was injected into unilateral muscles	MRI	intraperitoneal injection; magnetic field intensity of 1.5 T	¹⁶⁵165 Liu, G.; Hong, R. Y.; Guo, L.; Li, Y. G.; Li, H. Z.; Appl. Surf. Sci. 2011, 257, 6711.
PNIPAm	HeLa cells	delivery of DOX	Nd magnets	¹⁶⁶166 Kim, H.; Jo, A.; Baek, S.; Lim, D.; Park, S. Y.; Cho, S. K.; Chung, J. W.; Yoon, J.; Sci. Rep. 2017, 7, 41090.
CS nanofibers with Fe₃O₄	Caco-2 cells	hyperthermia	alternated EMF	¹⁶³163 Lin, T. C.; Lin, F. H.; Lin, J. C.; Acta Biomater. 2012, 8, 2704.
SPION-NHs (SPION + PPZ)	NIH3T3 mice fibroblast cells and U-87 MG human glioblastoma cells	MRI/hyperthermia	in vivo: EMF 19.5 kA m^-1, 389 kHz	¹⁶⁷167 Zhang, Z. Q.; Song, S. C.; Biomaterials 2016, 106, 13.
Magnetic alginate microbeads	CFC-7 cells	hyperthermia/release of DOX	EMF, 700 kHz and 27 mT	¹⁶⁸168 Brulé, S.; Levy, M.; Wilhelm, C.; Letourneur, D.; Gazeau, F.; Ménager, C.; Le Visage, C.; Adv. Mater. 2011, 23, 787.
Poly(N-isopropylacrylamide)/CS	fibrosarcoma tumor	hyperthermia in vivo	EMF: 325 or 390 Oe for 30 or 20 min	¹⁶⁹169 Jaiswal, M. K.; Gogoi, M.; Sarma, H. D.; Banerjee, R.; Bahadur, D.; Biomater. Sci. 2014, 2, 370.
PEG-phospholipid with Fe₃O₄ nanoparticles/gellan gum	RAW264.7; 4T1 cells (breast tumor) - in vivo	MRI/thermo-chemotherapy/release of PTX and DOX	in vitro heat: a water-cooled magnetic induction copper coil with 410 kHz and magnetic field intensity of 1.8 kA m^-1; MRI was carried out at 7.0 T with a 35 mm birdcage coil	¹⁷⁰170 Wu, H.; Song, L.; Chen, L.; Zhang, W.; Chen, Y.; Zang, F.; Chen, H.; Ma, M.; Gu, N.; Zhang, Y.; Acta Biomater. 2018, 74, 302.
Magnetic alginate-chitosan microspheres	MCF-7 cancer cells	hyperthermia/release of DOX	EMF: 40 kA m^-l, 265 kHz, 10 min	¹⁷¹171 Xue, W.; Liu, X. L.; Ma, H.; Xie, W.; Huang, S.; Wen, H.; Jing, G.; Zhao, L.; Liang, X.-J.; Fan, H. M.; J. Mater. Chem. B 2018, 6, 2289.
Magnetic HPMC	4T1 cells	hyperthermia/release of DOX	EMF: 400 kHz; 7.2 kW, coil diameter: 10 cm	¹⁷²172 Zhou, X.; Wang, L.; Xu, Y.; Du, W.; Cai, X.; Wang, F.; Ling, Y.; Chen, H.; Wang, Z.; Hu, B.; Zheng, Y.; RSC Adv. 2018, 8, 9812.

Matrix	Contaminant	Remark	Reference
Acrylamidopropyl-trimethylammonium chloride crosslinked with bisacrylamide and γ-Fe₂O₃ nanoparticles	Cr^VI	removal efficiency of 98%, 20 cycles	¹⁸⁰180 Tang, S. C. N.; Yan, D. Y. S.; Lo, I. M. C.; Ind. Eng. Chem. Res. 2014, 53, 15718.
Beads of carboxylated cellulose nanofibrils, amine-functionalized magnetite nanoparticles and PVA blended CS	Pb^II	q_max = 171 mg g^-1, four cycles	¹⁸¹181 Zhou, Y.; Fu, S.; Zhang, L.; Zhan, H.; Levit, M. V.; Carbohydr. Polym. 2014, 101, 75.
Magnetite, ZnO and dimethylacrylamide based copolymers	La^III, Co^II, Nd^III, Cu^II, Ni^II	good selectivity toward La^III ions, q_max = 58.8 mg g^-1, 6 cycles	¹⁸²182 Zheng, X.; Wu, D.; Su, T.; Bao, S.; Liao, C.; Wang, Q.; ACS Appl. Mater. Interfaces 2014, 6, 19840.
Fe₃O₄ nanoparticles and peach gum polysaccharide	Pb^II, Cd^II	q_max values: 277.0 mg g^-1 Pb^II and 141.4 mg g^-1 Cd^II	¹⁸³183 Huang, B.; Lu, M.; Wang, D.; Song, Y.; Zhou, L.; Carbohydr. Polym. 2018, 181, 785.
Prussian Blue-embedded magnetic PVA hydrogel	¹³⁷Cs	q_max = 41.15 mg g^-1; selective adsorption in the presence of Na⁺, Ca²⁺, Mg²⁺, K⁺	¹⁸⁴184 Yang, H. M.; Hwang, J. R.; Lee, D. Y.; Kim, K. B.; Park, C. W.; Kim, H. R.; Lee, K. W.; Sci. Rep. 2018, 8, 11476.
γ-Fe₂O₃ nanoparticles and alginate beads	Cu^II	q_max = 159.2 mg g^-1, five cycles	¹⁸⁵185 Zhu, H.; Fu, Y.; Jiang, R.; Yao, J.; Xiao, L.; Zeng, G.; Ind. Eng. Chem. Res. 2014, 53, 4059.
PVA and g-Fe₂O₃ hydrogels	Cd^II and Cu^II	q_max values: 71.3 mg g^-1 Cd^II and 73.0 mg g^-1 Cu^II, five cycles	¹⁸⁶186 Areal, M. P.; Arciniegas, M. L.; Horst, F.; Lassalle, V.; Sánchez, F. H.; Alvarez, V. A.; Gonzalez, J. S.; J. Polym. Environ. 2018, 26, 3129.
PVA/laponite and Fe₃O₄ hydrogels	Cd^II	q_max = 0.10 mg g^-1, at pH 2; adsorption capacity decreased with pH increase	¹⁸⁷187 Abasiyan, S. M. A.; Mahdavinia, G. R.; Environ. Sci. Pollut. Res. 2018, 25, 14977.
γ-Fe₂O₃ nanoparticles and alginate beads	La^III	q_max = 123.5 mg g^-1, five cycles	¹⁸⁸188 Wu, D.; Zhao, J.; Zhang, L.; Wu, Q.; Yang, Y.; Hydrometallurgy 2010, 101, 76.
Fe₃O₄ nanoparticles and chitosan - co-poly(methylenebisacrylamide)-co-poly(acrylic acid)	Pb^II, Cd^II and Cu^II	the addition of magnetic particles reduced up to 70% of pristine adsorption capacity	¹⁸⁹189 Paulino, A. T.; Belfiore, L. A.; Kubota, L. T.; Muniz, E. C.; Almeida, V. C.; Tambourgi, E. B.; Desalination 2011, 275, 187.
PAM-grafted CS and silica-coated Fe₃O₄ nanoparticles	Cu^II, Pb^II and Hg^II	at 298 K and pH 5.0; q_max values: 43.35 mg g^-1 Cu^II, 63.67 mg g^-1 Pb^II, and 263.9 mg g^-1 Hg^II, 5 cycles, regeneration with EDTA	¹⁹⁰190 Li, K.; Wang, Y.; Huang, M.; Yan, H.; Yang, H.; Xiao, S.; Li, A.; J. Colloid Interface Sci. 2015, 455, 261.
CMS-g-PVI, PVA and Fe₃O₄ crosslinked by glutaraldehyde	Crystal Violet (CV) and Congo Red (CR) dyes; Pb^II, Cu^II and Cd^II	q_max values: 65.00 mg g^-1 Pb^II, 83.60 mg g^-1 Cu^II, 53.20 mg g^-1 Cd^II, 83.66 mg g^-1 CR and 91.58 mg g^-1 CV, four cycles	¹⁹¹191 Pour, Z. S.; Ghaemy, M.; RSC Adv. 2015, 5, 64106.
p-Sulfonated calix[4,6]arene derivatives and Fe₃O₄	benzidine, p-chloroaniline, α-naphthylamine	highest adsorption capacity at pH 3	¹⁹²192 Aksoy, T.; Erdemir, S.; Yildiz, H. B.; Yilmaz, M.; Water, Air, Soil Pollut. 2012, 223, 4129.
Novel sodium alginate supported tetrasodium thiacalix[4]arene tetrasulfonate and Fe₃O₄	Cu^II, Cd^II, Pb^II, Co^II, Ni^II and Cr^III	q_max values: 11.1 mg g^-1 Cu^II, 18.9 mg g^-1 Cd^II, 20.0 mg g^-1 Pb^II, 15.0 mg g^-1 Co^II, 13.5 mg g^-1 Ni^II and 15.5 mg g^-1 Cr^III	¹⁹³193 Lakouraj, M. M.; Mojerlou, F.; Zare, E. N.; Carbohydr. Polym. 2014, 106, 34.
Fe₃O₄ nanoparticles, xylan and poly(acrylic acid)	methylene blue	q_max = 438.6 mg g^-1	¹⁹⁴194 Sun, X.-F.; Liu, B.; Jing, Z.; Wang, H.; Carbohydr. Polym. 2015, 118, 16.
Carboxymethyl-β-cyclodextrin and Fe₃O₄	methylene blue	q_max = 277.8 mg g^-1	¹⁹⁵195 Badruddoza, A. Z. M.; Hazel, G. S. S.; Hidajat, K.; Uddin, M. S.; Colloids Surf., A 2010, 367, 85.
Hydroxypropyl methylcellulose crosslinked with citric acid and EDTA impregnated with Fe₃O₄	17α-ethinyl estradiol	q_max = 0.6 mg g^-1, five cycles	¹⁹⁶196 Novaes, S. D.; Oliveira, P. V.; Petri, D. F. S.; ChemPlusChem 2017, 82, 904.
Graphene oxide foam Fe₃O₄	Cr^VI	q_max = 258.6 mg g^-1, reduction of Cr^VI to Cr^III	¹⁹⁷197 Lei, Y.; Chen, F.; Luo, Y.; Zhang, L.; J. Mater. Sci. 2014 , 49, 4236.
Chitosan and Fe₃O₄	Acid Red 2 (dye)	q_max = 90.06 mg g^-1	¹⁹⁸198 Kadam, A. A.; Lee, D. S.; Bioresour. Technol. 2015, 193, 563.
CS, β-cyclodextrin and Fe₃O₄	2-aminopyridine	q_max = 46.5 mg g^-1, five times	¹⁹⁹199 Zhang, W.; Zhu, Z.; Zhang, H.; Qiu, Y.; Int. J. Environ. Res. Public Health 2017, 14, 991.

[1] *e-mail: dfsp@iq.usp.br

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Magneto-Responsive Hydrogels: Preparation, Characterization, Biotechnological and Environmental Applications