A perspective on magnetic core–shell carriers for responsive and targeted drug delivery systems

Figures & data

Figure 1 Illustration of a ligand-mediated active targeting.

Notes: A carrier(1) loaded with the drug (2) is treated with a ligand (3) capable of recognizing the binding positions (4) on the surface of the cell (5). Reprinted by permission from Springer Nature Customer Service Centre GmbH: Springer Nature. Passive and active drug targeting drug delivery to tumors as an example. By Torchilin VP. In: Schäfer-Korting M, editor. Drug Delivery. Handbook of Experimental Pharmacology. Berlin, Heidelberg: Springer; 2009:3–53. Copyright 2009.⁷⁴

Figure 2 In passive targeting (A), drug targeting can be described as passive when nanoparticles diffused via the leaky tumor vessels. While in active targeting (B), drug delivery took place when the ligands of the nanocarriers were attached to the receptor on the tumor cells.

Notes: Reprinted by permission from Springer Nature Customer Service Centre GmbH: Springer Nature. Systemic targeting systems-EPR effect, ligand targeting systems. By Pawar PV, Domb AJ, Kumar N. In: Domb AJ, Khan W, editors. Focal Controlled Drug Delivery. Boston, MA: Springer US; 2014:61–91. Copyright 2014.⁷⁵

Abbreviation: NP, nanoparticle.

Table 1 Fundamental characteristics of a targeted drug delivery system

Features	Effect on drug delivery system
The rate of carrier delivery (encapsulated with the drug) to the targeted sites	• An adequate amount of a drug should be delivered to the desired sites • The free drug should reach a particular concentration in the targeted area
The rate of carrier elimination (encapsulated with the drug) from the targeted sites	• The drug should remain in the desired area for a sufficient time • Elimination process of carrier drug conjugate should not be faster than the delivery process
The duration between drug release and drug removal in the targeted sites	• The drug should retain a specific concentration in the targeted tissues for sufficient time to act on it
The rate of drug release at non-targeted sites	• Releasing the drug at non-targeting tissue will reduce the amount of drug delivered to the intended areas • The systematic toxicity will increase
The rate of carrier drug conjugate removal from the body	• The rate of drug elimination from the circulation system should be faster than its transition rate from the targeted tissues to the central compartment of the body

Figure 3 Classifications of shells for magnetic nanoparticles encapsulation.

Figure 4 Schematic illustration describing the effective nanocombinations therapy.

Notes: Reprinted with permission from Vivek R, Thangam R, Kumar SR, et al. HER2 targeted breast cancer therapy with switchable “Off/On” multifunctional “Smart” magnetic polymer core-shell nanocomposites. ACS Appl Mater Interfaces. 2016; 8(3):2262–2279. Copyright © 2016, American Chemical Society.¹²³

Figure 5 TEM results of (A–C) SG-1, (D–F) SG-2, and (G–I) SG-3 composites.

Notes: The composites prepared with 0.22, 0.31, and 0.45 mmol of TEOS were named as SG-1, SG-2, and SG-3 composites, respectively. Reproduced from Uribe Madrid SI, Pal U, Kang YS, Kim J, Kwon H, Kim J. Fabrica tion of Fe₃O₄@mSiO₂ core-shell composite nanoparticles for drug delivery applications. Nanoscale Res Lett. 2015;10(1):217. Copyright © Uribe Madrid et al.; licensee Springer. 2015. Creative Commons License available from: https://creativecommons.org/licenses/by/4.0/legalcode.¹⁷¹

Abbreviations: TEM, transmission electron microscopy; TEOS, tetraethylorthosilicate.

Figure 6 Ibuprofen release rate in different wall thicknesses.

Notes: Reproduced from Uribe Madrid SI, Pal U, Kang YS, Kim J, Kwon H, Kim J. Fabrica tion of Fe₃O₄@mSiO₂ core-shell composite nanoparticles for drug delivery applications. Nanoscale Res Lett. 2015;10(1):217. Copyright © Uribe Madrid et al.; licensee Springer. 2015. Creative Commons License available from: https://creativecommons.org/licenses/by/4.0/legalcode.¹⁷¹

Figure 7 (A) Synthesis of magnetic iron oxide–calcium silicate mesoporous core–shell nanocomposites with a hollow structure using two liquid phase system and ultrasound irradiation in the presence of isooctane. (B, C) TEM of the nanocomposites fabricated by using two liquid phase systems and ultrasound irradiation in the presence of isooctane.

Notes: Reprinted with permission from Lu BQ, Zhu YJ, Ao HY, Qi C, Chen F. Synthesis and characterization of magnetic iron oxide/calcium silicate mesoporous nanocomposites as a promising vehicle for drug delivery. ACS Appl Mater Interfaces. 2012;4(12):6969–6974. Copyright © 2012, American Chemical Society.¹⁸⁵

Abbreviations: TEM, transmission electron microscopy; TEOS, tetraethylorthosilicate.

Figure 8 Schematic illustration of the synthesis of DLMCs.

Notes: Reprinted with permission from Cao Z, Yue X, Li X, Dai Z. Stabilized magnetic cerasomes for drug delivery. Langmuir. 2013;29(48):14976–14983. Copyright © 2013, American Chemical Society.¹⁹⁴

Abbreviations: DLMC, DOX-loaded magnetic cerasome; DOX, doxorubicin.

Figure 9 SLB-MNPs consisted of iron oxide–silica nanoparticles enclosed in a cationic lipid bilayer that contains the amphiphilic DOX.

Notes: Reprinted with permission from Mattingly SJ, O’Toole MG, James KT, Clark GJ, Nantz MH. Magnetic nanoparticle-supported lipid bilayers for drug delivery. Langmuir. 2015;31(11):3326–3332. Copyright © 2015, American Chemical Society.¹⁹⁵

Abbreviations: DOX, doxorubicin; MNP, magnetic nanoparticle; SLB, supported lipid bilayer.

TorchilinVPPassive and active drug targeting drug delivery to tumors as an exampleSchäfer-KortingMDrug Delivery Handbook of Experimental PharmacologyBerlin, HeidelbergSpringer2009353

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PawarPVDombAJKumarNSystemic targeting systems-EPR effect, ligand targeting systemsDombAJKhanWFocal Controlled Drug DeliveryBoston, MASpringer US20146191

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VivekRThangamRKumarSRHER2 targeted breast cancer therapy with switchable “Off/On” multifunctional “Smart” magnetic polymer core-shell nanocompositesACS Appl Mater Interfaces2016832262227926771508

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Uribe MadridSIPalUKangYSKimJKwonHKimJFabrication of Fe3O4@mSiO2 core-shell composite nanoparticles for drug delivery applicationsNanoscale Res Lett201510121726034415

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LuBQZhuYJAoHYQiCChenFSynthesis and characterization of magnetic iron oxide/calcium silicate mesoporous nanocomposites as a promising vehicle for drug deliveryACS Appl Mater Interfaces20124126969697423210766

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CaoZYueXLiXDaiZStabilized magnetic cerasomes for drug deliveryLangmuir20132948149761498324188471

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MattinglySJO’TooleMGJamesKTClarkGJNantzMHMagnetic nanoparticle-supported lipid bilayers for drug deliveryLangmuir201531113326333225714501

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