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Global Translational Medicine SPION for cancer theranostics

temperatures, the use of toxic reagents, and the poor water Similarly, PLGA, renowned for its exceptional
solubility of the resulting NPs. biocompatibility and biodegradability, is extensively
studied in biomedical applications, including drug
2.5. Sonochemical method delivery and MRI. Its polymeric scaffold provides high
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The sonochemical synthesis method is an efficient and drug-loading efficiency, making it particularly effective for
adaptable technique for producing monodispersed carrying significant amounts of hydrophobic drugs.
SPIONs with a narrow size distribution using high- PVA, a hydrophilic, biocompatible, and biodegradable
intensity ultrasonic waves. This technique relies on polymer, is commonly used for NP functionalization. 23,24
acoustic cavitation, where microbubbles develop, expand, PVA coating significantly improves the colloidal stability
and collapse in a liquid, generating shock waves that of NPs by preventing aggregation and ensuring uniform
trigger chemical reactions as well as extremely high dispersion in aqueous and other solutions. 16,25 The hydroxyl
local temperatures (up to 5000 K) and pressures (up to groups in PVA also enable further functionalization,
1000 atm). This method is faster and more energy- allowing the attachment of biomolecules, drugs, or
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efficient compared to other traditional methods. Surface targeting agents, making it highly versatile for biomedical
functionalization can be achieved by introducing applications. Moreover, PVA coating serves as a protective
surfactants or polymers during the synthesis process. barrier, shielding cells from direct exposure to the iron
oxide core and reducing cytotoxic effects.
3. Protection or stabilization of SPIONs
Dextran, a biocompatible and neutral polysaccharide,
Stability is a crucial requirement for nearly all types of is widely used for coating SPIONs and has found extensive
biomedical applications of SPIONs. Uncoated NPs are prone applications in areas such as MRI imaging of the liver and
to agglomeration and cluster formation as they attempt to cancer treatment. 16,25 Its coating enhances colloidal stability
minimize their high surface area-to-volume ratio, leading and prolongs the blood circulation time of SPIONs, making
to reduced colloidal stability and diminished functionality. them highly suitable for in vivo applications. Natural
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Coating the surface of SPIONs not only improves their polymers such as dextran have been successfully used
colloidal stability but also offers a protective barrier against in clinical applications like Feridex due to their excellent
oxidation. Furthermore, selecting an appropriate coating biocompatibility.
enables functionalization, allowing the attachment of
specific molecules or functional groups to tailor the NP’s Chitosan is a hydrophilic, biocompatible, and non-
properties for a wide range of applications (Figure 3). toxic copolymer (poly-aminosaccharide) composed
of 2-amino-2-deoxy-β-D-glucan units linked through
3.1. Stabilization of SPIONs with polymer coating glycosidic bonds. 16,30 Due to its amine and hydroxyl groups,
SPIONs can be coated using synthetic polymers, such as chitosan is widely utilized in pharmaceutical applications.
PEG, polyvinyl alcohol (PVA), and poly(D, L-lactic-co- Its coating properties prevent the agglomeration of NPs
glycolic acid) (PLGA) to improve hydrophilicity, reduce and enable functionalization of their surfaces, enabling the
protein adsorption, and minimize immune system attachment of biological entities such as drugs and proteins,
recognition. This coating also allows SPIONs to circulate making it highly favorable for drug delivery applications. 26
in the bloodstream for extended periods by preventing Polymeric liposomes composed of amphiphilic
agglomeration and enhancing colloidal stability through octadecyl-quaternized lysine-modified chitosan (OQLCS),
steric hindrance. Among these, PEG, a biodegradable PEGylated OQLCS, and folate-conjugated OQLCS, can
polymer widely used in biomedical applications, offers be used in combination with SPIONs to improve their
numerous advantages for SPION coating. Its hydrophilic, biocompatibility and bioavailability while avoiding non-
biocompatible, and non-toxic nature makes it particularly specific uptake of NPs by healthy tissues. In this system,
effective for NP functionalization. The presence of SPIONs are either encapsulated within or attached to
PEG on the NP surface imparts stealth properties and polymeric liposomes. In addition, this system enables
hydrophilicity, helping to maintain prolonged blood surface functionalization by facilitating the attachment
circulation. 14,22 In addition, PEG coating enhances the of targeting ligands, such as antibodies and peptides,
NPs’ ability to cross cell membranes due to its solubility for specific cell targeting. This nanocomposite system
in both polar and non-polar solvents, as well as its high combines imaging capabilities for diagnosis and drug
permeability. PEG is an ideal choice for biomedical delivery applications into one platform. However, stability
applications because it demonstrates outstanding solubility remains a concern, as liposomes can degrade over time.
and stability in aqueous solutions and maintains its stability An additional challenge is that high SPION loading could
in physiological saline. destabilize the liposome structure.

Volume 4 Issue 2 (2025) 36 doi: 10.36922/gtm.8464