The appeal of MOFs begins with their architecture. Metal centers or clusters act as nodes, joined by organic linkers into extended three-dimensional crystalline networks whose pores can be adjusted with near-atomic precision. Because researchers can independently vary the metal, the linker and the functional groups decorating the pore walls, MOFs offer record-breaking internal surface areas, tunable pore sizes and a modular versatility that rigid inorganic adsorbents such as zeolites struggle to match. The review categorizes frameworks into rigid structures suited to molecular sieving, flexible or breathing frameworks whose unit cells expand and contract as guest molecules enter and leave, and surface-functionalized frameworks grafted with groups such as amines, sulfonates or carboxylates that dramatically alter adsorption affinity, hydrophobicity and stability. Open metal sites, generated when coordinated solvent molecules are stripped away during activation, add another handle for tuning performance; the copper framework HKUST-1, for example, adsorbs notably more carbon dioxide in the presence of a small amount of water.

A substantial portion of the review is devoted to how these materials are actually made, because the synthesis route shapes everything from crystallinity to cost. Solvothermal and hydrothermal methods remain the workhorses, producing highly crystalline frameworks such as MIL-101(Cr) and UiO-66, but they demand high temperatures and pressures, large volumes of organic solvents and long reaction times that limit scalability. Microwave-assisted synthesis slashes reaction times and yields uniform nanocrystals with high phase purity, yet scaling microwave equipment to industrial throughput is difficult. Sonochemistry accelerates nucleation with cavitation bubbles that momentarily reach thousands of kelvin, producing nanoscale MOFs with high surface areas, though controlling particle size distribution remains a challenge. Mechanochemical routes grind metal salts and linkers together in ball mills with little or no solvent, offering a genuinely green option at room temperature, at the cost of somewhat lower crystallinity. Electrochemical synthesis, first used by BASF to make HKUST-1 in 2005, supplies metal ions through anodic dissolution of a metal electrode, avoiding corrosive counterions and enabling continuous production. The authors conclude that no method is universally ideal: high crystallinity and tunability favor solvothermal chemistry, while green scalability increasingly points toward mechanochemical and continuous-flow techniques.

In the environmental arena, the review highlights MOFs as adsorbents and catalytic degradation platforms for three major classes of pollutants: synthetic dyes, heavy metals and emerging contaminants. Dye pollution is a serious concern because many residual dyes are carcinogenic and persist in water systems. Frameworks from the UiO, ZIF and MIL families, along with their composites, capture both cationic dyes such as methylene blue, rhodamine B and malachite green and anionic dyes such as methyl orange and congo red. The removal mechanisms operate in synergy: electrostatic attraction between oppositely charged dye molecules and framework surfaces, pi–pi stacking between the aromatic rings of dyes and the organic linkers, hydrogen bonding between surface functional groups and dye molecules, and size-selective pore filling. Because the surface charge of a MOF depends on solution pH and the functional groups present, researchers can engineer adsorbents that switch selectivity simply by decorating the pore walls.

Heavy metals present an even sterner test because they are non-biodegradable and toxic at low concentrations. MOFs bind Pb(II), Cr(VI), As(III/V) and Hg(II) through a combination of ion exchange, surface complexation, chelation, electrostatic interaction and redox conversion. Functionalization with thiol or amine groups markedly boosts selectivity for soft, highly toxic ions such as Hg(II), while redox-active iron-based frameworks can reduce toxic Cr(VI) to the far less hazardous Cr(III), coupling detoxification with immobilization. The review also emphasizes MOF-based membranes, formed when MOF crystals self-assemble on porous supports, which combine tunable pore sizes with high selectivity and recyclability for continuous water purification. The trade-offs are candidly acknowledged: MIL-101(Cr) offers enormous mesoporous cages that handle bulky dye and pharmaceutical molecules, but zirconium-based UiO-66 provides superior chemical robustness, and ZIF-8 resists water yet suffers from narrow pore apertures that restrict diffusion of large contaminants.

The second half of the review turns to biomedicine, where the requirements are far stricter than in industrial applications. An effective MOF drug carrier must encapsulate therapeutics at high loading, degrade in a controlled manner, release its cargo on demand, present acceptable toxicology and lend itself to surface engineering that dictates its fate in the body. MOFs meet these criteria in ways that conventional carriers such as liposomes, mesoporous silica and polymeric nanoparticles often cannot: their surface areas permit exceptionally high drug loading, pores of up to six nanometers accommodate molecules ranging from small-molecule drugs to peptides and large biomolecules, and their relatively weak coordination bonds allow the framework to decompose harmlessly and release its components. Loading can be achieved by diffusion into preformed crystals, by covalent attachment to the external surface, by in situ encapsulation during synthesis, or by using the drug itself as a ligand in framework construction.

Concrete examples illustrate the promise. A chiral zinc-based framework built from triazine-triisophthalate linkers absorbed the anticancer drug 5-fluorouracil through hydrogen bonding at a loading of 0.5 grams per gram and released it slowly over a week in buffered saline. In antibacterial applications, the iron framework MIL-53(Fe) physically loaded the glycopeptide antibiotic vancomycin to nearly 20 percent by weight and, under the acidic conditions that mimic a bacterial infection, released it in a controlled fashion that achieved 99.3 percent efficacy against Staphylococcus aureus while remaining biocompatible in vitro. ZIF-8 has been used to ferry the broad-spectrum cephalosporin ceftazidime, confirmed by element mapping in electron microscopy, and to co-deliver doxorubicin with the P-glycoprotein inhibitor verapamil in folate-targeted, PEG-coated particles that overcame multidrug resistance in tumor cells. A biomimetic nanoreactor combining ZIF-8 with the prodrug tirapazamine, the enzyme glucose oxidase and an erythrocyte membrane coating points toward cancer starvation therapy with improved delivery.

The range of biomedical uses continues to broaden. Copper nanowires sheathed in ZIF-8 slowed the release of antiviral copper ions, showed low cytotoxicity with 99 percent of kidney cells surviving after 48 hours, and were investigated against SARS-CoV-2 in infected cells; surface-functionalized MOFs bearing nystatin, folic acid or tenofovir can bind viral capsid proteins and immobilize viruses. Copper–BTC films grown directly on stent surfaces catalyze the production of nitric oxide from blood-borne s-nitroso-cysteine, improving blood compatibility, while MOF–polymer coatings have been shown to inhibit bacterial attachment to medical tubing under flow. Frameworks delivering ibuprofen to reduce brain inflammation or dopamine for neurological therapy, along with ATP-responsive zirconium systems, extend the concept into chronic disease management, although crossing the blood–brain barrier remains a formidable hurdle.

The review is refreshingly blunt about the obstacles that stand between laboratory success and clinical or industrial deployment. MOF toxicity, driven by metal ion release, particle size, shape and aggregation, can produce oxidative stress, inflammation and organ damage, and standardized toxicity testing protocols and long-term in vivo biocompatibility data are still lacking. Water stability in real treatment streams, biodegradability in physiological settings, regeneration and reuse of adsorbents, material costs and the reproducibility of green synthesis routes all demand further work. Compared with clinically established liposomes and hydrogels, MOFs carry biosafety uncertainty and more complex, expensive synthesis. Yet the trajectory is clear. With defect engineering, biocompatible metal choices, scalable continuous-flow production and rational linking of synthesis conditions to structure–performance relationships, the authors argue, these crystalline cages could become central platforms for sustainable water purification and personalized medicine alike, addressing some of the most pressing environmental and health challenges of the coming decades.

Subject of Research: Metal–organic frameworks for wastewater treatment and targeted drug delivery

Article Title: Emerging roles of metal organic frameworks in wastewater treatment and targeted drug delivery applications

Article References: Singh, P., Singh, G., Singh, C. K., Nitin, V., & Sodhi, K. K. (2026). Emerging roles of metal organic frameworks in wastewater treatment and targeted drug delivery applications. Discover Industrial Chemistry and Materials, 1(1), Article 12. https://doi.org/10.1007/s44508-026-00010-1

Image Credits: AI Generated

DOI: 10.1007/s44508-026-00010-1

Keywords: metal–organic frameworks, MOF synthesis, wastewater treatment, heavy metal adsorption, dye removal, drug delivery, targeted cancer therapy, biocompatibility, MOF membranes, stimuli-responsive release, antibacterial agents, water purification