Functionalities | Organic groups for binding | Binding method | Possible interference with |
---|---|---|---|
Antibodies, proteins, streptavidin, enzymes | -COOH -CH=O (aldehyde) -SH | EDC/NHS Direct interaction Direct interaction Direct interaction |
-NH2
-NH2 -NH2, -OH, -COOH -Br, -I |
DNA | -NH2
-NHR, -NR2 |
Electrostatic Electrostatic | -CH=O (aldehyde), epoxy -Br, -I, -Cl -Br, -I, -Cl |
Folic acid/folate | -NH2 | EDC/NHS | -COOH -CH=O (aldehyde), epoxy -Br, -I, -Cl |
FITC, RITC, TRITC (any isothiocyanated fluorophores) | -NH2
|
Direct interaction | -CH=O (aldehyde) epoxy -Br, -I, -Cl |
Drugs (negatively charged) | -NH2
-NHR, -NR2 |
Electrostatic Electrostatic | -CH=O (aldehyde) epoxy -Br, -I, -Cl -Br, -I, -Cl |
Drugs (positively charged) | -COOH | Electrostatic | epoxy |
Cholic acid | -NH2
|
EDC/NHS | -COOH, -CH=O (aldehyde), epoxy -Br, -I, -Cl |
EDC: 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide; NHS: N-hydroxysuccinimide
Coating materials | MNP types | Specific functional molecules | Applications | Ref. |
---|---|---|---|---|
Dextran | Fe3O4 | Transferrin | Targeted MRI | [37] |
g-Fe2O3 (10 nm) | Folic acid | Magnetic hyperthermia | [80] | |
Fe3O4 (5 nm) | 18F | PET-CT scan | [81] | |
Fe3O4 (8 nm) | 64Cu | PET-MRI scan | [82] | |
Chitosan | Fe3O4 (20 nm) | – | MRI | [83] |
Fe3O4 (8–11 nm) | Papain | Biocatalysis | [84] | |
Fe3O4 (10–11 nm) | – | Magnetic hyperthermia | [85] | |
Fe3O4 (10–16 nm) | FITC | Fluorescence imaging | [86] | |
Starch | Fe3O4 (6 nm) | – | MRI | [87] |
Fe3O4 (8 nm) | AGKGTPSLETTP peptide (A54) and doxorubicin | Drug delivery (doxorubicin) | [88] | |
Fe3O4 (10–11 nm) | – | Magnetic hyperthermia | [85] | |
Polylysine | Fe3O4 (35 nm) | – | Cell labeling | [89] |
Fe3O4 | – | Gene delivery | [90] | |
Polyethylene glycol | Fe3O4 (10 nm) | Chlorotoxin and Cy5.5 | MRI and fluorescence imaging | [41] |
Fe3O4 (10 nm) | Methotrexate | MRI and drug delivery | [42] | |
Fe3O4 (10 nm) | Folic acid | MRI | [43] | |
Polylactic acid | Fe3O4 (5–10 nm) | Noscapine | Drug delivery | [44] |
Polyglycolic acid | Fe3O4 (5–10 nm) | Noscapine | Drug delivery | [44] |
Poly(lactide-co-glycolide) | Fe3O4 (10–15 nm) FeCo (7–23 nm) |
HER antibody and doxorubicin – |
Drug delivery (doxorubicin) MRI |
[91] [92] |
Polycaprolactone | Fe3O4 (5–15 nm) | Cisplatin and gemcitabine | Drug delivery | [46] |
Polyvinyl alcohol | Fe3O4 | Cy3.5, Texas Red | Cell labeling | [45] |
Polyethyleneimine | Fe3O4 (11–25 nm) | – | Gene delivery | [93] |
Fe3O4 (5–10 nm) | – | Gene delivery | [94] | |
Gold | Fe (19 nm) | – | MRI | [95] |
Silica | Fe3O4 (10 nm) [97] |
|||
Aminopropyl silica | Fe3O4 (15 nm) | 188Re | Radiotherapy | [52] |
Fe3O4 (10 nm) | Bovine serum albumin | Magnetic hyperthermia | [98] | |
Meso-2,3- dimercaptosuccinic acid | g-Fe2O3 (3–15 nm) | Bovine serum albumin | Cell labeling | [99] |
Humphrey H P Yiu
Chemical Engineering, School of Engineering & Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
Tel.: +44 131 451 8145 Fax: +44 131 451 3129 h.h.yiu@hw.ac.uk
Magnetic nanoparticles (MNPs) with a multifunctional surface can be assembled using various chemical principles, but there could be unwanted reactions between organic groups during assembly.
The first coating of MNPs forms the base for building a multifunctional surface, but is also influential to the assembly methodologies.
There are a number of strategies for assembling the multifunctional surface:
Grafting various organic groups on the polymer first coating. Use of functional polymers such as polyethyleneimine and chitosan can simplify the assembly.
Use of copolymers of multiple functionalities on blocks.
Cocondensation of alkoxysilanes creating a multifunctional surface.
Building on the first silanized layer using organic chemistry.
Use of chelating ligands to self-assemble a multifunctional surface.
Exploiting nanoporous molecular sieves for size exclusion of functional biomolecules.
Assembly of multifunctional MNPs of higher complexity are expected to be reported in the next few decades. The holy grail is to assemble an all-in-one 'magic bullet' with combined diagnostic, monitoring and therapeutic capability.
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