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Global Translational Medicine Eco-friendly biomedical materials: A review

while green methods provide a sustainable alternative, synthesis of ZIF-8 with 2-methyl imidazole as a hydrogen
traditional synthesis methods remain valuable as their bond donor and quaternary ammonium salts as a hydrogen
parameters and behaviors often parallel those of green bond acceptor, obtaining a ZIF-8 material with increased
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approaches. 84 CO uptake without the need for a toxic solvent. On lower
2
synthesis temperatures, ZIF-67 films were prepared by Lo et
2.6. Zeolitic imidazolate framework (ZIF) al. using ultralow temperature-CVD (ULT CVD) at 140°C
Metal-organic frameworks (MOF) are materials formed under an argon atmosphere, providing a synthesis method
by metallic ions and organic ligands that possess specific suitable for direct application on electronic devices. The
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properties such as low density, high surface-to-volume main biomedical applications for ZIF materials include
ratio, and porosity. As with other nanomaterials, these drug delivery, antimicrobial activity, biosensors, and
@
properties are controlled by the size and shape of the imaging. Magnetic Fe O ZIF-8 NPs were proposed by Cai
3
4
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material, specifically the length, structure, and coordination et al. for the release of norfloxacin through a pH-sensitive
mode of the organic ligands. ZIF is a subgroup of MOFs mechanism, along with antimicrobial activity against
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with additional physical and chemical properties such as Escherichia coli. Studies like this one are necessary to
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chemical and thermal stability, pore control, and variety in decide the release conditions by MOFs as one of the greatest
their structure, 86,87 as noted by Park et al. who reported 12 challenges is the non-uniform drug release, compromising
types of ZIF materials, with two of them (ZIF-8 and ZIF-11) effective drug concentration. In addition, although
having high stability of up to 550°C and chemical resistance antimicrobial activity is desirable, long-term damage can
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to boiling water and organic solvents. As with other occur to human cells as well. Limitations of MOFs can
MOFs, ZIFs are formed by the reaction of transition metals also be seen in biosensing and imaging applications. 97-99
(e.g., Zn, Co, Fe) with organic ligands such as imidazole Even though many studies have been conducted on in vitro
or imidazole derivatives (Figure 7). For the previously samples, most of them did not report an evaluation of real
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mentioned reaction, the typical synthesis methods are samples such as urine, blood, or tissues. 100-102 MOFs have
solvothermal and hydrothermal synthesis with a wide potential in the biomedical area but further studies must be
range of reaction temperatures (from room temperature up carried out for more specific applications.
to 200°C) and times (from hours to days). In this instance,
solvents such as ethanol and N, N-dimethylformamide, or 3. Carbon nanomaterials
mixtures of organic solvents, which decompose in toxic 3.1. Carbon nanotubes
components and consequently result in risks and pollution The first successful synthesis of CNTs was conducted by
for the environment, are utilized. Iijima through an arc-discharge evaporation method.
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The formation of ZIF materials can be adapted to These nanotubes are classified by their structure as
follow the principles of green synthesis by the usage of single-walled (SWCNTs), double-walled (DWCNTs), and
greener solvents, reduced synthesis temperatures, and multi-walled (MWCNTs) carbon nanotubes, as shown
renewable materials as well as other synthesis methods in Figure 8. CNTs have been recently introduced in
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such as microwave-assisted synthesis and ultrasound- pharmacy and medicine for drugs, biomolecules and
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assisted synthesis. Kenyotha et al. proposed a water-based gene delivery, tissue regeneration, and biosensors. 105-107
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Figure 7. Structure of ZIF-8: Zn (polyhedral), N (sphere), and C (line) obtained from the reaction between 2-Melm and Zn(NO ) . Reproduced from
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Kouhdareh et al. Copyright © 2023, The Royal Society of Chemistry.
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Abbreviation: ZIF: Zeolitic imidazolate framework.

Volume 3 Issue 4 (2024) 7 doi: 10.36922/gtm.4698