Zinc-based Metal-organic Framework Research Articles

A novel design of copper selenide/zinc selenide/Nitrogen-doped carbon derived from MOF for sulfadiazine adsorption: Performance and mechanism

Herein, a novel copper selenide/zinc selenide/Nitrogen-doped carbon (Cu2Se/ZnSe/NC) sphere was constructed via a combination of cation exchange, selenization and carbonization approaches with zinc-based metal–organic frameworks (ZIF-8) as precursor for sulfadiazine (SDZ) removal. Compared with the ZnSe/NC, the defective Cu2Se/ZnSe interface in the optimizing Cu-ZnSe/NC2 sample caused a remarkably improved adsorption performance. Notably, the adsorption capacity of 129.32 mg/g was better than that of mostly reported adsorbents for SDZ. And the adsorption referred to multiple-layer physical–chemical process that was spontaneous and exothermic. Besides, the Cu-ZnSe/NC2 displayed fast adsorption equilibrium of about 20 min and significant anti-interference ability for inorganic ions. Specially, the adsorbent possessed excellent stability and reusability, which could also be applied for rhodamine B (RhB), methylene blue (MB), and methyl orange (MO) dyes removal. Ultimately, the charge redistribution of Cu2Se/ZnSe interface greatly contributes the superior adsorption performance for SDZ, in which electrostatic attraction occupied extremely crucial status as compared to π-π electron-donor–acceptor (π-π EDA) interaction and hydrogen bonding (H-bonding), as revealed by the density function theory (DFT) calculations and experimental results. This study can provide a guideline for design of high-efficient adsorbent with interfacial charge redistribution.

Tailoring MOF-5 Photocatalysts: Low-Temperature Synthesis and Solvent Variations for Enhanced Performance in Dye Degradation

Metal-organic frameworks (MOFs) are emerging as pivotal porous crystalline materials with diverse applications. Typically, MOFs are synthesized using solvothermal techniques at high temperatures and pressures. In this study, a novel approach was employed to synthesize zinc-based MOFs, specifically MOF-5, at low temperatures (up to 50 °C) via chemical mixing at standard pressures. Varying the temperature and solvents, N-methyl-2-pyrrolidone (NMP) and N,N-dimethylformamide (DMF), in the chemical mixing process, the highest yield of the material was observed with DMF at 50 °C (M1). Two additional samples, M2 and M3, are synthesized at room temperature using DMF and NMP, respectively. Despite similarities in XRD, Raman, and FTIR analyses confirming successful MOF-5 formation, noticeable differences in sample morphology arise due to distinct synthesis conditions, particularly solvent and temperature variations. The MOF-5 samples exhibit UV absorption with varying band gaps. Notably, when employed as photocatalysts for organic dye (methylene blue) degradation, M2 outperforms others, achieving an impressive 85% degradation under simulated solar light irradiation. This work underscores the significance of tuning MOF photocatalyst properties through tailored synthesis routes, recognizing the profound impact of morphology and elemental composition on enhancing photocatalytic dye degradation performance. Copyright © 2024 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

A (3,12)-connected metal-organic framework based on hexanuclear zinc cluster for iodine capture

The adsorption of discharged radioactive iodine is considered an important method to address this environmental problem. Metal-organic framework (MOF) materials are expected to be potential materials for capturing iodine. In this work, a new zinc-based MOF, namely [Zn6(OH)6(DMTDC)3(TPB)]·0.5DMF (JOU-31), was successfully prepared under solvothermal condition (H2DMTDC = 3,4-dimethylthieno [2,3-b]thiophene-2,5-dicarboxylic acid, TPB = 1,3,5-tris(4-pyridyl)benzene, DMF = N,N-Dimethylformamide). Structural analyses revealed that JOU-31 was a three-dimensional porous structure based on hexanuclear zinc-oxide clusters. Topologically, the framework of JOU-31 can be simplified to a (3,12)-connected net with new Schläfli symbol of {43·630}{43}2. Due to its large specific surface area, abundant electron-rich N/S sites, and high stability, JOU-31 was applied to capture iodine. The saturated iodine adsorption capacity of JOU-31 in n-hexane solution was 822 mg g−1. In addition, the interaction mechanism between JOU-31 and the adsorbed iodine was further explored in detail. This work provides a valuable clue for the preparation of new MOFs for iodine adsorption.

Phosphoramide-Based Metal-Organic Frameworks for Effective Gas Adsorption.

Cost-effective and facile synthetic routes to organic ligands, along with porous materials that exhibit exceptional gas-storage properties, promise significant industrial applications. Here, a two-step synthesis of novel organophosphorus ligands without metal catalysts is reported. These ligands serve as versatile linkers for the construction of metal-organic frameworks (MOFs) incorporating various metal ions, including zinc and copper. One of the zinc-based MOFs demonstrates remarkable gas-storage properties, with a hydrogen (H2) capacity exceeding 2.5 wt% at 77 K and 100 kPa as well as a carbon dioxide (CO2) capacity exceeding 20 wt% at 298 K and 100 kPa. Furthermore, this zinc-based MOF can be synthesized through a solvothermal process on the gram scale that yields high-quality single crystals.

Rapid synthesis of metal-organic framework CALF-20 in H2O/methanol solution under room temperature and normal pressure

In this study, a new process to synthesize Calgary framework 20 (CALF-20), a zinc-based metal-organic framework (MOF), in a H2O/methanol solution was developed, exhibiting a high CO2 adsorption capacity. Generally, CALF-20 was synthesized by a solvothermal method, requiring the consumption of considerable thermal energy. On the other hand, the proposed synthetic process required only 6 min to crystallize CALF-20 in a H2O/methanol mixed solution at room temperature (298 K) and normal pressure (101.3 kPa). In addition, CALF-20 was obtained in 93.3 % yield using zinc and oxalate sources under an aging time of 120 min. As-synthesized CALF-20 exhibited a Brunauer–Emmett–Teller surface area of 520 m2 g−1, a micropore volume of 0.19 cm3 g−1, a CO2 uptake of 3.84 mmol g−1 at 298 K, and a PCO2 of 100 kPa; these values were similar to those obtained for CALF-20 synthesized by the solvothermal method using high thermal energy. Furthermore, CALF-20 was crystallized without washing using H2O.The key factor for the crystallization of the CALF-20 structure in this process was the deprotonation of 1,2,4-triazole, which was caused by the acetate anion derived from zinc acetate as the starting metal source.

Elaborate Design of Two Novel Fluorescent Zinc-based Metal-Organic Frameworks for Highly Efficient Tetracycline Antibiotics Detection

Elaborate Design of Two Novel Fluorescent Zinc-based Metal-Organic Frameworks for Highly Efficient Tetracycline Antibiotics Detection

Connection based novel AL topological descriptors and structural property of the zinc oxide metal organic frameworks

Metal organic frameworks (MOFs) play a vital role in a variety of processes such as heterogeneous catalysis, heterogeneous gas purification and division, biocompatibility, toxicity, and biomedical applications. The Zinc-based MOFs, particularly, have gained prominence in the biomedical industry for applications such as drug delivery, biosensing, and cancer imaging, which has attracted the interest of researchers from around the world. Given the significant influence of molecular structure on the properties of MOFs, it is imperative to model and characterize this structure comprehensively to deepen our understanding and explore avenues for property enhancement. Topological indices are numerical parameters derived from the graph representation of molecules that quantify specific structural features. These indices provide insights into the connectivity and arrangement of atoms or nodes within the structure, offering information about its chemical, physical, or biological properties. In this study, the Zinc Oxide network structures are topologically modeled via connection numbers, and some novel topological descriptors viz. AL 1, AL 2, AL3, AL4, AL5, AL6, AL7andAL8 are computed by deriving mathematical closed form expressions for them. Based on the numerical results, a comparative analysis of the computed topological descriptors is also performed. The prediction potential and chemical applicability of these indices are investigated using the benchmark dataset of Octane Isomers and corresponding experimental values, correlating experimental and computed values through regression models.

Bioactive glass doped with zinc-based metal–organic frameworks (Zn/MOF) nanoparticles for antibiotic delivery applications

Zn-MOF/bioactive glass nanoparticles were successfully prepared using quick–alkali-modified sol–gel and tested for gentamicin drug delivery. Samples of 0 and 0.8 mol% Zn MOF contents (BG and BG/Zn MOF, respectively) were characterized using XRD, FTIR, TEM, and SEM/EDX. In addition, zeta characteristics and surface area parameters were also evaluated. Moreover, the cell viability of the prepared samples was tested against the osteosarcoma MG-63 cell line to evaluate the ability of prepared samples for bone regeneration. In addition, the antimicrobial activity of glass samples with and without antibiotics was determined against different microorganisms. Finally, the samples were loaded with gentamicin drug, and drug release profile and kinetics were studied too. XRD and FTIR results confirmed the physicochemical properties of the prepared samples. TEM results showed that particles were in the nano-sized range in both samples; however, the presence of Zn MOF increased the dispersity of particles. Both samples were bioactive, as indicated by hydroxyapatite formation on their surfaces. Cytotoxicity estimation of prepared materials exhibited their safe and nontoxic nature. BG/Zn MOF sample demonstrated prolonged drug release and excellent antimicrobial activity in comparison to BG alone. Therefore, the present study provides promising preliminary results regarding the usage of BG/Zn MOF nanoparticles loaded with gentamicin as an effective approach for bone regeneration.Graphical

Photoluminescence and photocatalytic degradation studies of Zn-based nanoparticles on malachite green dye

Water, the most fundamental source of life, is contaminated by various organic pollutants, especially organic dyes from the dying industry. The photocatalytic degradation of malachite green (MG) was studied using a zinc-based metal-organic framework (Zn-BTC MOF) and ZnO. Thermally decomposing Zn-MOF synthesized ZnO and its structural and optical properties were analyzed using various spectroscopic techniques. This article focuses primarily on the wavelength-dependent photoluminescence properties of Zn-MOF and ZnO materials and their role in the photocatalytic degradation of MG dye in water. Zn-MOF and ZnO photocatalysts exhibited a photodegradation efficiency of approximately 99% after 40 min of visible light exposure. Based on kinetic experiments, the degrading efficiency of these catalysts followed pseudo-first-order reaction kinetics with a correlation of R2 = 0.99 and a rate constant of 0.031 min−1. This manuscript is helpful to researchers working on ZnO and Zn-MOF materials for photocatalytic and environmental applications.

Exploring the Performance Improvement for CO2 Chemical Fixation in Zn/ZnMg-MOFs.

A new 3D zinc-based metal-organic framework {[Zn7L2(DMF)3(H2O)(OH)2]·5DMF}n (1) (H6L = 5,5',5″-(methylsilanetriyl) triisophthalic acid) was constructed with an organosilicon-based linker, where H6L is a tetrahedral structure furnished with rich -COO- chelating sites for Zn(II) immobilization. Compound 1 exhibited two types of irregular one-dimensional channels and a three-dimensional skeleton with large specific surface area, making it a promising catalytic platform. Moreover, by incorporation of the second metal ion into the inorganic node of framework 1, isomorphic bimetallic MOF ZnMg-1 was successfully synthesized. ZnMg-1 demonstrated enhanced catalytic activity compared to 1 under identical conditions. Contrast experiments and theoretical calculations indicate that bimetallic active sites play a facilitating role in the chemical fixation of epoxides and CO2. It indicated that efficient chemical fixation of CO2 to cyclic carbonates was obtained over isomorphic MOF catalysts 1 and ZnMg-1.

Eu3+-Doped Anionic Zinc-Based Organic Framework Ratio Fluorescence Sensing Platform: Supersensitive Visual Identification of Prescription Drugs.

Advanced techniques for both environmental and biological prescription drug monitoring are of ongoing interest. In this work, a fluorescent sensor based on an Eu3+-doped anionic zinc-based metal-organic framework (Eu3+@Zn-MOF) was constructed for rapid visual analysis of the prescription drug molecule demecycline (DEM), achieving both high sensitivity and selectivity. The ligand 2-amino-[1,1'-biphenyl]-4,4'-dicarboxylic acid (bpdc-NH2) not only provides stable cyan fluorescence (467 nm) for the framework through intramolecular charge transfer of bpdc-NH2 infinitesimal disturbanced by Zn2+ but also chelates Eu3+, resulting in red (617 nm) fluorescence. Through the synergy of photoinduced electron transfer and the antenna effect, a bidirectional response to DEM is achieved, enabling concentration quantification. The Eu3+@Zn-MOF platform exhibits a wide linear range (0.25-2.5 μM) to DEM and a detection limit (LOD) of 10.9 nM. Further, we integrated the DEM sensing platform into a paper-based system and utilized a smartphone for the visual detection of DEM in water samples and milk products, demonstrating the potential for large-scale, low-cost utilization of the technology.

MOF-on-MOF heterostructure boosting AIE sensing and triggered structural collapse for histamine detection

We explored a novel preparation method for MOF-on-MOF heterostructured material (Zn-BTEC@ZIF-8). This prepared heterostructured material acts as a container, capable of adsorbing tetracycline hydrochloride molecules into its backbone through hydrogen bonding and π-π interactions. This phenomenon triggers an aggregation induced emission (AIE) effect, leading to the formation of luminescent bodies. The coordination between histamine and MOF was found to collapse the originally stabilized MOF-on-MOF structure. This collapse causes the splitting of the initially stabilized MOF-on-MOF structure from the aggregated state into fragments, resulting in the quenching of fluorescence in the fluorophore. Remarkably, the fluorescence quenching efficiency of this composite surpasses that of single-layer metal−organic framework (MOF) zeolitic imidazolate framework-8 (ZIF-8) or zinc-based MOF of pyromellitic acid (Zn-BTEC), enabling more sensitive detection of histamine. In this investigation, we constructed a label-free fluorescent sensor specifically designed for the detection of histamine, capitalizing on the AIE effect inherent in MOF-on-MOF architecture and the presence of tetracycline hydrochloride (Tet). The sensor demonstrates a rapid, straightforward, and stable response, allowing for histamine detection within 20 min. Notably, the sensor covers a detection range of 2–400 mg L−1, achieving a low detection limit of 1.458 mg L−1 The practical application of this sensor for quantitative detection of histamine in river water and various fish species exhibited robust performance, ensuring reliability and accuracy in real samples. Its potential application in food safety and environmental monitoring is evident, making it a valuable tool for addressing histamine-related challenges in these domains.

A novel Zn-MOF fluorescent probe for highly sensitive and rapid detection of gossypol in cottonseed oil and fetal bovine serum

Gossypol is a poisonous substance in cottonseed which seriously harms the internal organs, blood vessels, nerves, and reproductive systems of organisms. Therefore, detecting gossypol is of great significance in the field of food safety. This manuscript constructs a novel target-oriented gossypol fluorescence probe based on the energy competition absorption mechanism. The probe is a zinc-based metal organic framework material (Zn-MOF) with blue fluorescence, which can achieve rapid and sensitive detection of gossypol through fluorescence “turn-off” effect. It has the advantages of low detection limit (16.6 nM), ultra-fast response time (8 s), and favorable selectivity. Interestingly, this probe can be reused and the fluorescence can still be recovered after five cycles when detecting gossypol. In addition, the application of the fluorescent probe in cottonseed oil and fetal bovine serum is reliable, with the recovery of 99.35%–101.5% and the relative standard deviation of less than 2.72%. These results indicate that the developed sensor has prominent application potential in the field of food and biological detection.

New metal-organic framework coated sodium alginate for the delivery of curcumin as a sustainable drug delivery and cancer therapy system

The utilization of biocompatible drug delivery systems with extended drug release capabilities is highly advantageous in cancer therapy, as they can mitigate adverse effects. To establish such a biocompatible system with prolonged drug release behavior, researchers developed an innovative drug carrier. In this study, a sustainable approach was employed to synthesize a new zinc-based metal-organic framework (Zn-MOF) through the reaction between synthesized Schiff base ligands and zinc ions. Comprehensive analyses, including FT-IR, XRD, SEM, BET surface area, and TGA techniques, were employed to thoroughly characterize the frameworks. Following comprehensive characterization, curcumin (CUR) was loaded onto the Zn-MOF, resulting in CUR entrapment efficiency and loading capacity of 79.23 % and 26.11 %, respectively. In vitro evaluations of CUR release from CUR@MOF exhibited controlled release patterns, releasing 78.9 % and 50.0 % of CUR at pH 5.0 and pH 7.4, respectively. To mitigate initial burst release, a coating of the biopolymer sodium alginate (SA) was applied to CUR@Zn-MOF. In vitro CUR release tests indicated that SA/CUR@Zn-MOF outperformed pristine CUR@Zn-MOF. The release of CUR conformed to the Korsmeyer-Peppas model, displaying non-Fickian diffusion. Furthermore, an in vitro cytotoxicity study clearly demonstrated the potent anti-tumor activity of the synthesized CUR@Zn-MOF attributed to its controlled release of CUR. This led to the induction of apoptotic effects and cell death across HeLa, HEK293, and SH-SY5Y cell lines. These findings strongly suggest that the developed pH-sensitive carriers hold remarkable potential as targeted vehicles for drug delivery in cancer therapy.

Bioinspired Zn-MOF doped radial porous chitosan-based sponge with antibacterial and antioxidant properties for rapid hemostasis and wound healing

Herein, a novel bioinspired radial porous zinc-based metal-organic framework (Zn-MOF) doped sodium alginate/chitosan derivatives/pullulan-based SA/PSCS/Pul/Zn-MOF (SPCP/Zn) composites sponge with excellent antioxidant and antibacterial properties was fabricated by the ice-templating method. Boric acid (BA) and Ca2+, which were respectively used as hydrogen- and ionic- bonding cross-linkers, provided strong mechanical properties for sponge matrix composed of SA, PSCS, and Pul. The obtained SPCP/Zn sponge exhibited uniform porous morphology, proper hydrophilicity, and admirable biocompatibility. In addition, the SPCP/Zn sponge achieved a sustained release of Zn2+ and gallic acid, which displayed powerful antibacterial and antioxidant activities. Importantly, the SPCP/Zn sponge exhibited shorter rapid hemostasis (20.4 ± 2.9 s) and lower blood loss (19.8 ± 4.3 mg). The SPCP/Zn sponge also showed faster wound closure ratio for the rat full-thickness skin defect model. It was revealed that SPCP/Zn sponge could significantly accelerate and enhance wound healing through downregulating inflammatory cytokines (TNF-α, IL-6) and increasing the expression of growth factors (VEGF). Due to its excellent properties, the SPCP/Zn sponge may have promising potential in wound healing applications.

Redox Active Zn@MOFs as Spontaneous Reactive Oxygen Species Releasing Antimicrobials.

The rapid development of antimicrobial resistance (AMR) among infectious pathogens has become a major threat and challenge in healthcare systems globally. A strategy distinct from minimizing the overuse of antimicrobials involves the development of novel antimicrobials with a mode of action that prevents the development of AMR microbial strains. Reactive oxygen species (ROS) are formed as a natural byproduct of the cellular aerobic metabolism. However, it becomes pathological when ROS is produced at excessive levels. Exploiting this phenomenon, research on redox-active bactericides has been demonstrated to be beneficial. Materials that release ROS via photodynamic, thermodynamic, and photocatalytic interventions have been developed as nanomedicines and are used in various applications. However, these materials require external stimuli for ROS release to be effective as biocides. In this paper, we report novel zinc-based metal organic framework (Zn@MOF) particles that promote the spontaneous release of active ROS species. The synthesized Zn@MOF spontaneously releases superoxide anions and hydrogen peroxide, exhibiting a potent antimicrobial efficacy against various microbes. Zn@MOF-incorporated plastic films and coatings show excellent, long-lasting antimicrobial potency even under continuous microbial challenge and an aging process. These disinfecting surfaces maintain their antimicrobial properties even after 500× surface wipes. Zn@MOF is also biocompatible and safe on the skin, illustrating its broad potential applications in medical technology and consumer care applications.

Removal and fluorescence detection of antibiotics from wastewater by layered double oxides/metal-organic frameworks with different topological configurations

Owing to the serious potential side-effects on the environment and human health, the rapid detection and removal of antibiotics have become an important research focus. In this work, four zinc-based metal-organic frameworks (MOFs) with different functional groups, i.e., Zn-MOF, Zn-MOF-CH3, Zn-MOF-NO2, Zn-MOF-COOH, were utilized for the construction of LDO/MOF composite materials with a nickel-iron-cobalt-based layered double oxide, NiFeCo-LDO. The results showed that the LDO/MOF composites not only had high sensitivity in detecting sulfonamide and quinolone antibiotics, but also had an appreciable ability to adsorb them from wastewater. The maximum adsorption capacities of all the four types of LDO@Zn-MOFs to all antibiotics can at least reach 150 mg/g, and the limits of detection in relation to all four antibiotics were at least as low as 100 µg/L. Our work suggested the dual-function extraction performance can be attributed to the synergistic effects between the LDO and the MOFs. Moreover, the strong ferromagnetism derived from the LDO provided great convenience for the separation and regeneration of the LDO/MOF composites.

Metal Organic Framework-Incorporated Three-Dimensional (3D) Bio-Printable Hydrogels to Facilitate Bone Repair: Preparation and In Vitro Bioactivity Analysis.

Hydrogels are three-dimensional (3D) water-swellable polymeric matrices that are used extensively in tissue engineering and drug delivery. Hydrogels can be conformed into any desirable shape using 3D bio-printing, making them suitable for personalized treatment. Among the different 3D bio-printing techniques, digital light processing (DLP)-based printing offers the advantage of quickly fabricating high resolution structures, reducing the chances of cell damage during the printing process. Here, we have used DLP to 3D bio-print biocompatible gelatin methacrylate (GelMA) scaffolds intended for bone repair. GelMA is biocompatible, biodegradable, has integrin binding motifs that promote cell adhesion, and can be crosslinked easily to form hydrogels. However, GelMA on its own is incapable of promoting bone repair and must be supplemented with pharmaceutical molecules or growth factors, which can be toxic or expensive. To overcome this limitation, we introduced zinc-based metal-organic framework (MOF) nanoparticles into GelMA that can promote osteogenic differentiation, providing safer and more affordable alternatives to traditional methods. Incorporation of this nanoparticle into GelMA hydrogel has demonstrated significant improvement across multiple aspects, including bio-printability, and favorable mechanical properties (showing a significant increase in the compressive modulus from 52.14 ± 19.42 kPa to 128.13 ± 19.46 kPa with the addition of ZIF-8 nanoparticles). The designed nanocomposite hydrogels can also sustain drug (vancomycin) release (maximum 87.52 ± 1.6% cumulative amount) and exhibit a remarkable ability to differentiate human adipose-derived mesenchymal stem cells toward the osteogenic lineage. Furthermore, the formulated MOF-integrated nanocomposite hydrogel offers the unique capability to coat metallic implants intended for bone healing. Overall, the remarkable printability and coating ability displayed by the nanocomposite hydrogel presents itself as a promising candidate for drug delivery, cell delivery and bone tissue engineering applications.

One-Pot Preparation of HCPT@IRMOF-3 Nanoparticles for pH-Responsive Anticancer Drug Delivery

Metal–organic frameworks (MOFs) are considered to be promising materials for drug delivery. In this work, a Zinc-based MOF nanocomposite IRMOF-3 was introduced as a drug carrier for 10-hydroxycamptothecine (HCPT). Without an extra drug-loading process, a nanoscale drug delivery material HCPT@IRMOF-3 was prepared via one-pot synthesis. The composition and structure of the material were investigated, and the drug release character was measured. Compared with preparing IRMOF-3 first and loading the drug, the one-pot-prepared HCPT@IRMOF-3 exhibited a higher drug-loading capacity. The material presented pH-responsive release. The HCPT release rate at pH 5.0 was significantly higher than that at pH 7.4. The cytotoxicity experiments showed that IRMOF-3 was non-toxic, and HCPT@IRMOF-3 exhibited notable cytotoxicity to Hela and SH-SY5Y cells. One-pot synthesis is a simple and rapid method for the preparation of an MOF drug delivery system, and IRMOF-3 can be potentially used in pH-responsive drug delivery systems.

Carbon dots-embedded zinc-based metal-organic framework as an efficient fluorescent sensor for the detection of ferric and phosphate ions

Carbon dots were prepared from urea and sodium citrate using a microwave method which was combined with zinc nitrate and dimethylimidazole to prepare CDs@ZIF-8 composites using a one-pot method. It was used to develop a novel fluorescent sensor for the rapid and effective detection of Fe3+. Owing to intense contacts and electron transfer between CDs@ZIF-8 and Fe3+, the fluorescence was severely diminished. The burst fluorescence of the Fe3+ system was restored considerably due to a higher binding preference between Fe3+ and PO43-. Furthermore, the detection limit for Fe3+ was 5.2 μM. Our construction of a fluorescent sensor provides a simple and rapid platform for detecting Fe3+ and PO43- in human health and biodiversity.