title: Alginate/magnetite hybrid beads for magnetically stimulated release of dopamine.
abstract: Hybrid beads composed of magnetite nanoparticles (MNP) and alginate (Alg) were synthesized and coded as Alg-MNP. They were incubated in dopamine (DOPA) solution (5 g/L), at pH 7.4 and 8 °C, during 12 h, promoting the DOPA loaded magnetic beads, coded as Alg-MNP/DOPA. The release of DOPA was further evaluated in the absence and the presence of external magnetic field (EMF) of 0.4 T. The products Alg-MNP and Alg-MNP/DOPA were characterized by scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), Fourier transform infrared vibrational spectroscopy (FTIR), UV spectrophotometry, thermogravimetric analyses (TGA), inductively coupled plasma atomic emission spectroscopy (ICP-AES) analyses and superconducting quantum interference device (SQUID) magnetometer. The magnetic and chemical properties of Alg-MNP beads were not affected by DOPA loading. The incorporation of DOPA into the beads depended on the pH and on the negative charge density. At pH 7.4 38% of DOPA were loaded into Alg-MNP beads, whereas at pH 2 or using neat Alg beads (lower charge density than Alg-MNP) the loading efficiency decreased to one third or less. In the absence of EMF, 24% of the loaded DOPA was released from Alg-MNP at pH 7.4 over a period of 26 h. The released amount increased to 33% under the stimulus of EMF. A model was proposed to explain the loading efficiency of charged drugs, as DOPA, into hybrid beads and the role played by EMF on delivery systems, where drug and matrix are oppositely charged. The results suggest that the alginate combined with magnetite nanoparticles is a promising system for release of DOPA in the presence of EMF.
authors.affiliation: Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, 05508-000, São Paulo, Brazil.
authors.forename: Stalin
authors.initials: S
authors.lastname: Kondaveeti
authors.affiliation: Instituto de Física, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Cornejo
authors.affiliation: Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, 05508-000, São Paulo, Brazil. Electronic address: dfsp@usp.br.
authors.forename: Denise Freitas Siqueira
authors.initials: DF
authors.lastname: Petri
mesh_terms: D000464:Alginates / Q000737:chemistry*; D000465:Algorithms; D004298:Dopamine / Q000737:chemistry* / Q000493:pharmacokinetics; D015259:Dopamine Agents / Q000737:chemistry / Q000493:pharmacokinetics; D065546:Drug Liberation; D052203:Ferrosoferric Oxide / Q000737:chemistry*; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D060526:Magnetic Fields; D058185:Magnetite Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D015394:Molecular Structure; D013052:Spectrometry, X-Ray Emission; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D000464:Alginates; D015259:Dopamine Agents; D006603:Hexuronic Acids; D058185:Magnetite Nanoparticles; D020723:Glucuronic Acid; D004298:Dopamine; D052203:Ferrosoferric Oxide
keywords: Alginic acid sodium salt; Dopamine; External magnetic field; Magnetic beads; Magnetic stimuli; Release