## 1 Introduction
They reported 91.1% of drug release from MIL-101(Fe)-NH\({}_{2}\) at pH 7.4 after 24 h. [PERSON] et al. [25] incorporated acetaminophen into MIL-53(Fe), which was slowly liberated under simulated physiological conditions. It was found that 100% of the drug was released within 6 days. MIL-88A has been the subject of much research in the last decade as an adsorbent, catalyst, and energy harvester [26; 27; 28; 29; 30]. Its biocompatibility, low toxicity, easy synthesis via solvo/hydrothermal methods, and flexible structure render it an ideal candidate for drug hosting [26]. It is composed of non-toxic iron ions and fumaric acid--an endogenous linker and an important intermediate metabolite in the Krebs cycle [31]. In the case of its degradation in the body, the linker is metabolized, which decreases the risk of adverse effects (LD\({}_{50}\) (Fe) = 30 g/kg, LD\({}_{50}\) (fumaric acid) = 10.7 g/kg; LD--lethal dose) [23; 32]. The in vitro and in vivo cytotoxicity of MIL-88A was investigated in several studies. In [PERSON] and co-workers' research [32], 150 mg/kg/day of MIL-88A was injected into the rat liver and spleen for 4 days. After 10 days, there was no result in detectable toxicity. [PERSON] et al. [31] examined the in vivo acute toxicity of high doses (up to 220 mg/kg) of MIL-88A nanoparticles. After intravenous administration, the liver and spleen maintained their functionality without any indications of enduring toxicity, displaying only temporary anomalies. [PERSON] and co-workers [33] synthesized iron(III) fumarate nanoparticles under different conditions and carried out toxicity and cell association experiments. It was found that at concentrations up to 200 mg/mL, different forms of MIL-88A samples did not induce distinct impacts on cell viability within 24 h of exposure. The lack of immune or inflammatory responses following the administration of MIL-88A materials indicates their non-toxic nature [32]. MIL-88A was used as a carrier of different drugs and biologically active gases. [PERSON] et al. [34] utilized MIL-88(Fe) materials for nitric oxide adsorption and delivery. The results showed a substantial NO release at the biological level for prolonged periods. [PERSON] and co-workers [35] examined NH\({}_{2}\)-MIL-88(Fe) as a carrier for bromidine. The drug was encapsulated at a concentration of 121.3 \(\mathrm{\SIUnitSymbolMicro g}\)/mg and liberated in a controlled manner over 12 h. [PERSON] et al. [36] synthesized MIL-88(Fe) material on the surface of the carboxymethyl cellulose and used it as a delivery platform for a widely prescribed antibiotic: tetracycline. The sustained release of 64.3% tetracycline took place over 384 h. [PERSON] and co-workers [37] coated MIL-88A with 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC)-derived liposomes and applied it as irinotecan, floxuridine, and a Suberoyl bis-hydroxamic acid delivery system. The experiments demonstrated that the liposome-coated MIL-88A (Lip-MIL-88A) platform facilitated intracellular drug release, which could improve cancer treatment. Nevertheless, there is a lack of existing literature on the utilization of MIL-88A as a carrier of diclofenac sodium (DS), a phenylacetic acid widely used during migraine attacks. In addition, this drug is also employed in the management of lupus, rheumatic fever, psoriatic and rheumatoid arthritis, and gout [38]. Table 1 outlines the physicochemical properties and structure of DS. Diclofenac sodium is available on the market, mainly in the form of tablets, capsules, or gels. After oral administration, the bioavailability of the drug and its plasma half-life are approximately 50-60% and 1-2 h, respectively [39]. The necessity for multiple daily doses of this medication can lead to adverse outcomes, including gastrointestinal upset, increased risk of cardiovascular events, drug-induced hepatic damage, or diarrhea [40].