The development of novel multicomponent nanozymes with high catalytic efficiency and selectivity continues to be a focal point in contemporary research. In this work, a multilanthanide-containing phospho(III)tungstate [H2N(CH3)2]8Na12H16[La4(H2O)15W8(tart)3(H2tart)O20]2[H2P2W14O52]4·52H2O (1, H4tart = tartaric acid) was synthesized. Its polyoxoanion consists of two identical tartrate-stabilized tetra-La3+-substituted {La4(H2O)15W8(tart)3(H2tart)O20} units bridged by four multivacant Dawson-like [H2P2W14O52]12- fragments. Subsequently, 1 was subjected to ultrasonic treatment to form a nanofilm, which was then used as a guest material to coat MIL-(53)Fe (MILFe), preparing a series of core-shell heterostructured MILFe@1 composites. These MILFe@1 composites facilitate multielectron transfer and function as highly active nanozymes, significantly enhancing the catalytic oxidation of 3,3',5,5'-tetramethylbenzidine (TMB). Under optimized conditions, the MILFe@1-2 (1: MILFe = 1:2) composite demonstrates robust catalytic performance over a broad TMB concentration range without the need for H2O2. This work highlights the potential of integrating lanthanide-containing polyoxometalates with metal-organic frameworks to construct core-shell heterostructured nanozymes with enhanced catalytic efficiency. Concurrently, the polyoxometalate shell enables rapid electron transfer kinetics, which is crucial for enhancing the overall catalytic performance of the system.

Developing innovative chip-based sensors with high sensitivity for the recognition and detection of breast cancer biomarkers is of critical importance in reducing mortality rates and improving cure rates. In this research, a high-nuclear CeIII-PIII-WVI cluster-incorporated phospho(III)tungstate [H2N(CH3)2]22Na8[Ce24W12(H2O)42(H2ma)6(HPO3)18O30][(HP)2W14O52]6·200H2O (1, H3ma = malic acid) was synthesized, in which the polyanion of 1 can be conceptualized as the assembly of a CeIII-PIII-WVI [Ce24W12(H2O)42(HPO3)18O30]48+ cluster, six high-vacant Dawson-like [(HP)2W14O52]12- fragments, and malic acid ligands. Furthermore, thickness-controllable multilayered 1-PDDA films were fabricated on chips as sensing interfaces based on polydiallyldimethylammonium chloride (PDDA) and 1. The current response of the 1-PDDA chip can be modulated by the concentration of 1, which exhibits good conductivity. Accordingly, a p-DNA/1-PDDA chip-based sensor was developed, which demonstrates high sensitivity for the identification of microRNA-21 with a broad detection range (1 × 10-17 M - 1 × 10-9 M), a low limit of detection (1.19 × 10-18 M), and sensitivity. This work offers valuable insights into the synthesis of high-nuclearity poly(polyoxometalate) materials and further expands the potential applications of polyoxometalate-based materials by integrating them into chip-based sensor platforms through layer-by-layer assembly.

Developing innovative chip-based sensors with high sensitivity for the recognition and detection of breast cancer biomarkers is of critical importance in reducing mortality rates and improving cure rates. In this research, a high-nuclear CeIII-PIII-WVI cluster-incorporated phospho(III)tungstate [H2N(CH3)2]22Na8[Ce24W12(H2O)42(H2ma)6(HPO3)18O30][(HP)2W14O52]6·200H2O (1, H3ma = malic acid) was synthesized, in which the polyanion of 1 can be conceptualized as the assembly of a CeIII-PIII-WVI [Ce24W12(H2O)42(HPO3)18O30]48+ cluster, six high-vacant Dawson-like [(HP)2W14O52]12- fragments, and malic acid ligands. Furthermore, thickness-controllable multilayered 1-PDDA films were fabricated on chips as sensing interfaces based on polydiallyldimethylammonium chloride (PDDA) and 1. The current response of the 1-PDDA chip can be modulated by the concentration of 1, which exhibits good conductivity. Accordingly, a p-DNA/1-PDDA chip-based sensor was developed, which demonstrates high sensitivity for the identification of microRNA-21 with a broad detection range (1 × 10-17 M - 1 × 10-9 M), a low limit of detection (1.19 × 10-18 M), and sensitivity. This work offers valuable insights into the synthesis of high-nuclearity poly(polyoxometalate) materials and further expands the potential applications of polyoxometalate-based materials by integrating them into chip-based sensor platforms through layer-by-layer assembly.

A rigid nicotinate-modified lanthanide-substituted selenotungstate [H2N(CH3)2]6Na3H[La4SeW8(H2O)16(nica)2O28][SeW9O33]232H2O (1, Hnica = nicotinic acid) was synthesized and consists of two trivacant Keggin [B-alpha-SeW9O33]8- fragments and one unusual [SeW4O18]8- fragment bridged by a heterometallic [La4W4(H2O)16(nica)2O28]18- cluster. In the heterometallic cluster, two carboxyl O atoms in two nicotinate ligands directly coordinate with two W atoms in a stable C-O-W-O-W-O six-membered ring fashion. According to its catalase-like activity, 1 was utilized to catalyze the oxidation of 3,3 ',5,5 '-tetramethylbenzidine (TMB) by H2O2 to produce blue oxidized TMB (ox-TMB), which can be used to establish a colorimetric sensing method for the detection of ascorbic acid. This work not only provides a promising platform for detecting H2O2 and ascorbic acid but also expands the application potential of polyoxometalate-based materials in biological and clinical analyses.

Polyoxometalates (POMs) have drawn significant attention on account of their structural designability, compositional diversity and great potential applications. As an indispensable branch of POMs, selenotungstates (SeTs) have been synthesized extensively. Some SeTs have been applied as sensing materials for detecting biomarkers (e.g., metabolites, hormones, cancer markers). To gain a comprehensive understanding of advancements in SeT-based sensing materials, we present an overview that encapsulates the sensing performances and mechanisms of SeT-based biosensors. SeT-based biosensors are categorized into electrochemical catalytic biosensors, electrochemical affinity biosensors, "turn-off" fluorescence biosensors and "turn-on" fluorescence biosensors. We anticipate the expansive potential of SeT-based biosensors in wearable and implantable sensing technologies, which promises to catalyze significant breakthroughs in SeT-based biosensors. Recent progress of electrochemical and fluorescent biosensors of selenotungstate-based materials was summarized. This overview could provide insights for the continuous development of polyoxometalate-based biosensors.

Although two-dimensional (2D) materials with ultrathin geometry and extraordinary electrical attributes have attracted substantial concern, exploiting new-type 2D materials is still a great challenge. In this work, an unprecedented single-layer pure polyoxometalate (POM) 2D material (2D-1) was prepared by ultrasonically exfoliating a one-dimensional (1D)-chain heterometallic crystalline germanotungstate Na4[Ho(H2O)6]2[Fe4(H2O)2(pic)6Ge2W20O72]·16H2O (1) (Hpic = picolinic acid). The 1D polymeric chain of 1 is assembled from particular {Ge2W20}-based [Fe4(H2O)2(pic)6Ge2W20O72]10- segments through bridging [Ho(H2O)6]3+ cations. 2D-1 is formed by π-π interaction driving force among adjacent 1D polymeric chains of 1. Also, the peroxidase-mimicking properties of 2D-1 toward detecting H2O2 were evaluated and good detection result was observed with a limit of detection (LOD) of 58 nM. Density functional theory (DFT) calculation further confirms that 2D-1 displays outstanding catalytic activity and active sites are located on Fe centers and Hpic ligands. Under the catalysis of uricase, uric acid can be transformed to allantoin and H2O2, and then, H2O2 oxidizes TMB to its blue ox-TMB in the presence of 2D-1 as a catalyst. Then, we utilized this cascade reaction to detect uric acid, which also exhibits prominent results. This research opens a door to prepare ultrathin pure POM 2D materials and broadens the scope of potential applications of POMs in biology and iatrology.

An organic-inorganic hybrid trigonal pyramidal {SeO3} group, bridged cerium-inlaid polyoxometalate (POM) Na16[Se2Ce4(H2O)8W4(HPIC)4O10][B-β-SeW8O30]2[Se2W12O46]2·60H2O (1) (HPIC = 2-picolinic acid), containing two disparate selenotungstate (ST) building blocks was synthesized by a one-step assembly strategy, which is established by two asymmetric sandwich-type {[Ce2(H2O)4W2(HPIC)2O4][B-β-SeW8O30][Se2W12O46]}10- moieties joined by double trigonal pyramidal {SeO3} groups. Its outstanding structural trait is that it contains two types of ST building blocks, Keggin-type [B-β-SeW8O30]8- and Dawson-like [Se2W12O46]12-, which are extremely rare in ST chemistry. Remarkably, [Se2W12O46]12- is first obtained in lanthanide-inlaid STs. Furthermore, 1@PPy conductive film (PPy = polypyrrole) was prepared by electrochemical polymerization and served as the electrode material, and then nano-gold particles (NGPs) were deposited on the surface of 1@PPy conductive film by an electrochemical deposition method in order to immobilize the aptamer of ochratoxin A. With the help of exonuclease I (EN I), the oxidation peak of the metalized Ag works as the detection signal to achieve the detection of ochratoxin A (OTXA). This study offers an available approach for creating organic-inorganic hybrid heteroatom-bridged lanthanide-inlaid POMs and reveals the likelihood of extending heteroatom-bridged lanthanide-inlaid POMs into electrochemical biosensing applications.

Two particular fumaric acid bridging lanthanide-encapsulated selenotungstates [H2N(CH3)2]16Na8[Ln3(H2O)7]2 [W4O8(C4H2O4) (C4H3O4)]2[SeW6O25]2[B-α-SeW9O33]4·46H2O [Ln = Ce3+ (1), La3+ (2)] were acquired by the deliberately designed step-by-step synthetic strategy, which are composed of four trilacunary Keggin [B-α-SeW9O33]8- and two original [SeW6O25]10- building units together with one fumaric acid bridging heterometallic [Ln3(H2O)7]2[W4O8(C4H2O4) (C4H3O4)]228+ entity. Particularly, this heterometallic cluster contains four fumaric acid ligands, which play two different roles: one works as the pendant decorating the cluster and the other acts as the linker connecting the whole structure. In addition, the 1@DDA hybrid material was produced through the cation exchange of 1 and dimethyl distearylammonium chloride (DDA·Cl) and its beehive-shaped film of 1@DDA was prepared by the breath figure method, which can be further used to establish an electrochemical biosensor for detecting a kind of mycotoxin-ochratoxin A (OX-A). The 1@DDA beehive-shaped film-based electrochemical biosensor exhibits good reproducibility and specific sensing toward OX-A with a low detection limit of 29.26 pM. These results highlight the huge feasibility of long-chain flexible ligands in building lanthanide-encapsulated selenotungstates with structural complexity and further demonstrate great electrochemical application potentiality of polyoxometalate-involved materials in bioanalysis, tumor diagnosis, and iatrology.

An organic-inorganic hybrid trigonal pyramidal {SeO3} group, bridged cerium-inlaid polyoxometalate (POM) Na-16[Se2Ce4(H2O)(8)W-4(HPIC)(4)O-10][B-beta-SeW8O30](2)[Se2W12-O-46](2)center dot 60H(2)O (1) (HPIC = 2-picolinic acid), containing two disparate selenotungstate (ST) building blocks was synthesized by a one-step assembly strategy, which is established by two asymmetric sandwich-type {[Ce-2(H2O)(4)W-2(HPIC)(2)O-4][B-beta-SeW8O30][Se2W12O46]}(10-) moieties joined by double trigonal pyramidal {SeO3} groups. Its outstanding structural trait is that it contains two types of ST building blocks, Keggin-type [B-beta-SeW8O30](8-) and Dawson-like [Se2W12O46](12-), which are extremely rare in ST chemistry. Remarkably, [Se2W12O46](12-) is first obtained in lanthanide-inlaid STs. Furthermore, 1@PPy conductive film (PPy = polypyrrole) was prepared by electrochemical polymerization and served as the electrode material, and then nano-gold particles (NGPs) were deposited on the surface of 1@PPy conductive film by an electrochemical deposition method in order to immobilize the aptamer of ochratoxin A. With the help of exonuclease I (EN I), the oxidation peak of the metalized Ag works as the detection signal to achieve the detection of ochratoxin A (OTXA). This study offers an available approach for creating organic-inorganic hybrid heteroatom-bridged lanthanide-inlaid POMs and reveals the likelihood of extending heteroatom-bridged lanthanide-inlaid POMs into electrochemical biosensing applications.

Developing and exploring organic-inorganic hybrid multi-lanthanide (Ln) implanted hetero-polyoxometalates (HPOMs) has bloomed into an emerging research field. In this article, two neoteric D- gluconic acids (H6GA) concatenating multi-LnIII implanted heteropolytungstates K14H10[Ln4(H2O)4W6(H2-GA)4O12(B-a-TeW9O33)4]$60H2O (Ln = La3+ (1), Pr3+ (2)) were obtained in acidic aqueous system. Attrac-tively, in the polyanion structure of 1 and 2, six WVI and four LnIII centers are connected by four flexible H2GA4-ligands via carboxyl and hydroxyl groups, resulting in the heterometallic [Ln4(H2O)4W6(H2GA)4O12]8+ cluster and then the heterometallic cluster is surrounded by four [B-a- TeW9O33]8- segments.Electrochemical measurements for the 1@CFMCN/GCE sensor (CFMCN = carboxyl-functionalized multiwalled carbon nanotube; GCE = glass carbon electrode) demonstrate that 1@CFMCN/ GCE shows benign recognition response to detecting noradrenaline (NDA). This research expands the structural diversity of Ln-implanted HPOMs and presents an electrochemical platform of recognizing NDA in the field of biosensors. (c) 2021 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights reserved.

A family of rare 2, 6-pyridinedicarlmxylic acid decorated rare-earth (RE) -incorporated Keggin-type tellurotungstates(TTs) (PTEA)(7)H3K [RE2(B-alpha-TeW9O33)(3)W3O5(H2O)(3) (HDPA) ] center dot 22H(2)O [ RE=Ce3+(1) center dot Pr3+ (2) , Nd3+ (3) , Sm3+ (4) ; H(2)DPA=2, 6-pyridinedicarboxylic acid; PTEA=pmtonated triethanolamine] were synthesized by the one-step self-assembly strategy in NaAc aqueous solution via microwave heating method. The polyanion of isomorphic compounds 1-4 consists of three trivacant Keggin [B-alpha-TeW9O33](8-) building blocks linked by a {RE2W3O5(H2O)(3) (HDPA)}(13+ )heterometallic cluster. In this heterometallic cluster, HDPA as quadridentate ligand coordinates with two RE ions (RE1 and RE2) to form planar tri-heterocycle structure, which is perpendicular to the planar constructed by W2, W2A and W16 centers. Additionally, compound 1 can combinate with carboxylic multi-walled carbon nanotube(CMWCNT) to produce the 1-CMWCNT composite, which was then used as electrode material to establish electrochemical biosensor for detecting sequence-specific DNA.

An organic-inorganic hybrid Fe-III-Pr-III-included 2-germano-20-tungstate [Pr(H2O)(8)](2)H-2[Fe-4(H2O)(4) (pca)(4)Ge2W20O72].34H(2)O (Hpca = 2-pyridinecarboxylic acid) (1) was hydrothermally prepared. Its polyoxoanion comprises one tetra-Fe-III incorporated [Fe-4(H2O)(4)(pca)(4)Ge2W20O72](8-) hybrid entity and two [Pr(H2O)(8)](3+) ornamental cations. The [Fe-4(H2O)(4)(pca)(4)Ge2W20O72](8-) 2-germano-20-tungstate entity can be regarded as an infrequent S-type [Ge2W20O72](16-) cluster pocketed by four [Fe(H2O)(pca)](2+) cations. The S-type [Ge2W20O72](16-) cluster could be imagined as condensation of two divacant Keggin [alpha-GeW10O37](10-) segments by sharing two atoms. It is of interest is that carboxyl O and pyridine N atoms on pca ligands concurrently bind with Fe3+ cations in a five-membered heterocyclic fashion to increase the stability of the whole structure. Furthermore, the electrochemical biosensing properties of 1 as the modified electrode material have been investigated for detecting norepinephrine (NPP), showing a low detection limit of 3.25 mu mol/L. This work not only enriches structures of heterometallic germanotungstates (GTs), but also expands applications of polyoxometalates (POMs) in the electrochemical biosensing field. (C) 2021 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.

An organic-inorganic hybrid trigonal pyramidal {SeO3} group, bridged cerium-inlaid polyoxometalate (POM) Na16[Se2Ce4(H2O)8W4(HPIC)4O10][B-β-SeW8O30]2[Se2W12O46]2·60H2O (1) (HPIC = 2-picolinic acid), containing two disparate selenotungstate (ST) building blocks was synthesized by a one-step assembly strategy, which is established by two asymmetric sandwich-type {[Ce2(H2O)4W2(HPIC)2O4][B-β-SeW8O30][Se2W12O46]}10- moieties joined by double trigonal pyramidal {SeO3} groups. Its outstanding structural trait is that it contains two types of ST building blocks, Keggin-type [B-β-SeW8O30]8- and Dawson-like [Se2W12O46]12-, which are extremely rare in ST chemistry. Remarkably, [Se2W12O46]12- is first obtained in lanthanide-inlaid STs. Furthermore, 1@PPy conductive film (PPy = polypyrrole) was prepared by electrochemical polymerization and served as the electrode material, and then nano-gold particles (NGPs) were deposited on the surface of 1@PPy conductive film by an electrochemical deposition method in order to immobilize the aptamer of ochratoxin A. With the help of exonuclease I (EN I), the oxidation peak of the metalized Ag works as the detection signal to achieve the detection of ochratoxin A (OTXA). This study offers an available approach for creating organic-inorganic hybrid heteroatom-bridged lanthanide-inlaid POMs and reveals the likelihood of extending heteroatom-bridged lanthanide-inlaid POMs into electrochemical biosensing applications.

Two types of organic-inorganic hybrid structure-related lanthanide (Ln)-included selenotungstates (Ln-SeTs) [H2N(CH3)2]11Na7[Ce4(H2PTCA)2(H2O)12(HICA)]2[SeW4O17]2[W2O5]4[SeW9O33]4·64H2O (1, H3PTCA = 1,2,3-propanetricarboxylic acid, H2ICA = itaconic acid) and [H2N(CH3)2]6Na4[Ln4SeW8(H2O)14(H2PTCA)2O28] [SeW9O33]2·31H2O [Ln = Pr3+ (2), Nd3+ (3)] were obtained by Ln nature control. The primary frameworks of 1-3 are composed of trivacant Keggin-type [B-α-SeW9O33]8- and [SeW4Om]n- [Ln = Ce3+ (1), m = 17, n = 6; Ln = Pr3+ (2), Nd3+ (3), m = 18, n = 8] fragments bridged by organic ligands and Ln clusters. Intriguingly, Ln nature results in the degradation of hexameric 1 to trimeric 2-3. Besides, 1@DMDSA and 3@DMDSA composites (DMDSA·Cl = dimethyl distearylammonium chloride) were prepared through the cation exchange method, which were then reorganized to form two-dimensional (2D) honeycomb thin films by the breath figure method. Using these honeycomb thin films as electrode materials, the aptasensors were further established by utilizing methylene blue as an indicator and cDNA and Au nanoparticles as signal amplifiers to enhance the response signal so as to realize the purpose of ochratoxin A (OTA) detection. This work provides a new platform for detecting OTA and explores the application potential of POM-based composites in biological and clinical analyses.

An alkali-metal-lanthanide (AM-Ln)-embedded 19-tungsto-2-selenate derivative [H2N(CH3)2]8Na[CeNa (H2O)4(OH) WO(H2O)(B-alpha-SeW9O33)2]18H2O (1) was synthesized by a self-assembly reaction of Na2WO42H2O, Na2SeO3, Ce(NO3)36H2O, C2H7NHCl and 2,6-pyridinedicarboxylic acid in the mixed solvent of water and N,Ndimethylformamide (DMF) (v:v = 8: 2). The polyoxoanion of 1 is constructed by a semilunar [Se2W19O68]14fragment sandwiching an AM-Ln [CeNa(H2O)4(OH)]3+ dinuclear cluster. The [Se2W19O68]14- unit comprises two trivacant [B-alpha-SeW9O33]8- moieties and a central {WO6} bridging group, displaying an open configuration for grasping additional metal groups. Moreover, 1 was assembled with carboxyl-functionalized multi-walled carbon nanotube (CMWCNT) to fabricate the 1@CMWCNT composite, and was further modified onto glass carbon electrode (GCE) to construct 1@CMWCNT-GCE electrochemical sensor (ECS) for the detection of uric acid (UA), generating a low detection limit of 1.69 mu mol/L for UA. Notably, this work expands the application of polyoxometalate-based composite materials on detecting biomolecules.

Cluster-based functional materials have made remarkable progress owing to their wonderful structures and distinctive physicochemical performances, one of on-going advancements of which is basically driven by synthetic chemistry of exploring and constructing novel nanosized gigantic polyoxometalate (POM) aggregates. In this article, an unprecedented nanoscale hexameric arsenotungstate aggregate Na9K16H4[Er0.5K0.5(H2O)7][Er5W10O26(H2O)14][B-α-AsW9O33]6·102H2O (1) has been synthesized by the combined synthetic strategy of simultaneously using the arsenotungstate precursor and simple tungstate material in a highly acidic aqueous solution. The {[Er5W10O26(H2O)14][B-α-AsW9O33]6}31− polyanion in 1 consists of an intriguing dumbbell-shaped pentadeca-nuclear W-Er heterometal {Er5W10O26(H2O)14}23+ cluster connecting six trilacunary [B-α-AsW9O33]9− moieties, which has never been seen previously. Furthermore, through electropolymerization of 1 and pyrrole on the conductive substrate, a thickness-controllable and robust 1-PPY (PPY = polypyrrole) hybrid film was successfully prepared, which represents the first POM-PPY film assembled from high-nuclear lanthanide (Ln) encapsulated POM and PPY hitherto. The 1-PPY film-based electrochemical biosensor exhibits a favorable recognition performance for ochratoxin A in multiple media. This work not only provides a feasible combined synthetic strategy of the POM precursor and simple tungstate material for constructing complicated multi-Ln-inserted POM aggregates, but also offers a promising electrochemical platform constructed from POM-based conductive films for identifying trace biomolecules in complex environments.

Organic-inorganic hybrid metal-oxide clusters have been pursued for many years, benefiting from their abundant structures and prominent performances. Upon our exploration, a family of unusual mixed-heteroatom (Sb-III, P-III)-directing lanthanoid (Ln)-inserted heteropolyoxotungstates (Ln-HPOTs),[(CH3)(2)NH2](2)Na7H3[Ln(4)(HPIII) W-8(H2O)(12)(H(2)ptca)(2)O-28][(SbW9O33)-W-III] 2.27H(2)O [Ln = Ce3+(1), La3+ (2), Pr3+(3)], functionalized by 1,2,3-propanetricarboxylic acid (H(3)ptca) was achieved. The intriguing trimeric [Ln(4)(HPIII)W-8(H2O)(12)(H(2)ptca) O-2(28)][(SbW9O33)-W-III](2)(12-) polyanion was established by two trivacant [B-alpha(-SbW9O33)-W-III](9-) segments mounted on both sides and one rare [HPIIIW4O18](8-) segment at the bottom, which are bridged via an organic- inorganic hybrid [W(4)Ln(4)(H2O)(12)O-10(H(2)ptca)(2)](14+) central moiety. Such Ln-HPOTs involving dual-heteroatom-directing mixed building blocks, and even simultaneously modified by tricarboxylic ligands, are rather unseen in polyoxometalate chemistry. Moreover, the detection of 17 beta-estradiol through a 1-based electrochemical biosensor has been explored, demonstrating a low detection limit (7.08 x 10(-14) M) and considerable stability.

A novel organic-inorganic hybrid cerium-encapsulated selenotungstate comprising three polyoxotungstate building units Na16H6{[Ce3W4O10(H2O)9(CH3COO)3]2(Se2W7O30)(B-α-SeW9O33)4}·(C5H8NBO3)·119H2O (1) was synthesized by the portfolio approach of an in situ self-assembly reaction and step-by-step synthesis. The hybrid polyoxoanion of 1 is constructed from an acetate-coordinated heterometallic {[(Ce3W4O10)(H2O)9(CH3COO)3]2(Se2W7O30)}10+ core encompassing four trilacunary [B-α-SeW9O33]8- subunits. Interestingly, the heterometallic core contains a remarkable [Se2W7O30]10- building block in which seven WVI atoms form a W7 plane and two SeIV atoms are situated on two opposite faces of the W7 plane. In addition, the electrochemical performances of the 1@CFMCN composite (CFMCN: carboxyl-functionalized multiwalled carbon nanotube) were investigated. The 1@CFMCN/GCE (GCE: glass carbon electrode) sensor demonstrates a promising potential in electrochemically sensing dopamine (DPA) or paracetamol (PCM) or even simultaneously detecting DPA and PCM with low limits of 0.053 μM for DPA and 2.03 μM for PCM over a wide linear range at high sensitivity.

Under coordination driving force of tungsten and rare-earth (RE) bridges, we synthesized a novel giant multi-tungsten-and-RE-bridging octameric tellurotungstate (TT) [H2N(CH3)2]16K8Na6H10[Pr8(H2O)20W16O48][B-α-TeW9O33]8·70H2O (1) in CH3CN-H2O mixed solvent. The cluster anion {[Pr8(H2O)20W16O48][B-α-TeW9O33]8}40- features sixteen WVI bridges, eight PrIII bridges and eight trivacant Keggin [B-α-TeW9O33]8- fragments, which the square {W4O12} cluster can be imagined as a seed to induce the aggregation of eight [B-α-TeW9O33]8- fragments by coordination driving force of additional twelve WVI bridges and eight PrIII ions. Furthermore, the 2D 1@DODA (dimethyldioctadecyl ammonium bromide = DODA·Br) honeycomb composite material was prepared. The honeycomb morphology of the 1@DODA composite material provides rich binding sites for electrodepositing Au nanoparticles to make Au/1@DODA electrodes. The aptamer of 17β-estradiol (E2) hormone can be grafted to the Au/1@DODA electrodes via Au-S bonding interaction to construct the Au/1@DODA aptamer biosensors. By virtue of the specific recognition interaction of aptamer and the electrochemical signal amplification function of methylene blue and cDNA, the Au/1@DODA aptamer biosensors can realize the electrochemical detection of E2. This finding not only offers an electrochemical biosensing platform for detecting E2, but also expands POM-based composite materials in the applications of clinical detection and biological analysis.

A series of unprecedented mixed heteroatoms-oriented rare-earth-embedded heteropolyoxotungstates 1–8 were prepared and the 1@CMWCNT-GCE electrochemical sensing performances toward DA and UA were studied.