Band-Edge Effect-Induced Electrochemiluminescence Signal Amplification Based on Inverse Opal Photonic Crystals for Ultrasensitive Detection of Carcinoembryonic Antigen.

Photonic crystals (PCs) have emerged as a promising electrochemiluminescence (ECL) matrix in the domain of immunoassay. Making maximum use of light manipulation properties of PCs is highly desired for improving the sensitivity. In this work, we proposed a band-edge effect-induced ECL enhancement strategy based on silica inverse opal PCs (SIOPCs). By fine-tuning the lattice constant and carefully calibrating the stopband position, we found that the band edge of the stopband exerted significant influences on the ECL intensity and spectral distribution. The high density of states at the blue edge of the photonic band gap increased the radiative transition probability of ECL emitters and enhanced the photon extraction during propagation, giving rise to ∼20-fold ECL signal amplification accompanied by a redistributed ECL spectrum for the Ru(bpy)32+-TPrA system. In combination with the intrinsic structural superiority, like large specific surface area and interconnected macropores, the developed SIOPC electrode was successfully applied in constructing a sandwich-type immunosensor. The fabricated immunosensor displayed a very low detection limit of 0.032 pg/mL and a wide linear range of 0.1 pg/mL-150 ng/mL for a carcinoembryonic antigen assay, showing its potential application in disease diagnosis.

Three Cd(II) MOFs with Different Functional Groups: Selective CO2 Capture and Metal Ions Detection.

Three Cd(II) iso-frameworks {[Cd(BIPA)(IPA)]·DMF} n (1), {[Cd(BIPA)(HIPA)]·DMF} n (2), and {[Cd(BIPA)(NIPA)]·2H2O} n (3) were synthesized from the self-assembly of the BIPA ligand (BIPA = bis(4-(1 H-imidazol-1-yl)phenyl)amine) and different carboxylic ligands (H2IPA = isophthalic acid, H2HIPA = 5-hydroxyisophthalic acid, H2NIPA = 5-nitroisophthalic acid) with Cd(II), which have amino groups, amino and phenolic hydroxyl groups, and amino and nitro groups, respectively. Both 1 and 2 exhibit CO2 uptakes of more than 20 wt %, indicating that amino and phenolic hydroxyl functionalized groups are beneficial to CO2 adsorption. Their applications and mechanisms in detecting metal ions were researched. The results exhibit that 1 and 2 are dual-responsive photoluminescent sensors for Hg2+ and Pb2+ ions with low detection concentration and high quenching constant. Besides, like most MOFs, 3 can detect a trace quantity of Fe3+ and Cu2+.

H-Bonding Interactions Induced Two Isostructural Cd(II) Metal-Organic Frameworks Showing Different Selective Detection of Nitroaromatic Explosives.

Two luminescent Cd(II) metal-organic frameworks (MOFs) were prepared from electron-rich π-conjugated fluorescent ligands. They are isostructural with sql nets. Their strong luminescences can be quenched by a series of nitroaromatic explosives. Notably, MOF 1 shows highly selective and sensitive detection of 4-nitrophenol (4-NP), while MOF 2 exhibits good responses toward picric acid (PA) compared with other nitroaromatic explosives. This different order of quenching efficiency is because there are H-bonding interactions between MOF 1 and 4-NP, while MOF 2 lacks these H-bonding interactions. MOF 1 displays highly selective and sensitive detection of 4-NP with the high quenching constant (6.74× 104 M-1) and low detection limit (34.48 ppb), which is better than those of known MOFs. MOF 1 and MOF 2 have highly sensitive and selective detection of 4-NP and PA in the practical application, respectively.

Photoluminescent Inorganic Nanoprobe-based Pathogen Detection.

Pathogens are serious threats to human health, and traditional detection techniques suffer from various limitations. The unique optical properties of photoluminescent inorganic nanomaterials, such as high photoluminescence quantum yields, good photostability, and tunable spectra, make them ideal tools for the detection of pathogens with high specificity and sensitivity. In this review, the design strategies, working mechanisms, and applications of photoluminescent inorganic nanomaterial-based probes in pathogen detection are introduced. In particular, the design and construction of stimuli-responsive nanoprobes and their potential in these fields are highlighted.

Three Zn(ii)-based MOFs for luminescence sensing of Fe3+ and Cr2O72- ions.

Three zinc metal-organic frameworks (MOFs), {ZnL(chd)}n (1), {[Zn(L)0.5(oba)]·DMF·H2O}n (2) and {[Zn(L)0.5(sdb)]·H2O}n (3) [L = E,E-2,5-dihexyloxy-1,4-bis-(2-pyridin-vinyl)-benzene; H2chd = 1,4-cyclohexanedicarboxylic acid, H2oba = 4,4'-oxybisbenzoic acid, H2sdb = 4,4'-sulfonyldibenzoic acid], have been hydrothermally synthesized. We explored their applications in detecting ions, and the result shows that they all show highly selective sensing for Fe3+ and Cr2O72- ions.

Two MOFs as dual-responsive photoluminescence sensors for metal and inorganic ion detection.

Two metal-organic frameworks (MOFs), [Zn(BIPA)(tfbdc)]n (1) and {[Cd(BIPA)(tfbdc)(H2O)]·DMF}n (2), were hydrothermally synthesized using the self-assembly of the "V-shape" BIPA ligand (bis(4-(1H-imidazol-1-yl)phenyl)amine) and the H2tfbdc ligand (2,3,5,6-tetrafluorobenzene-1,4-dicarboxylic acid) with Zn/Cd metal salts. 1 is a 2D hcb framework and 2 is a 2D sql network. Their applications in detecting metal and inorganic ions were also explored. The results indicate that 1 exhibits dual-responsive photoluminescence sensing for Fe3+ and Cr2O72- ions while 2 can detect Hg2+ and Cr2O72- ions.

Cd-Based metal-organic frameworks from solvothermal reactions involving in situ aldimine condensation and the highly sensitive detection of Fe3+ ions.

Four Cd(ii)-based compounds (1-4) were synthesized from solvothermal reactions involving the in situ aldimine condensation of an o-diamino-functionalized precursor 3,6-di(4H-imidazol-4-yl)benzene-1,2-diamine (L), Cd(NO3)2·4H2O and aldehyde. Two modes of cycloaddition ([4 + 1] cycloaddition and [4 + 2] cycloaddition) occurred during condensation, causing the in situ generation of two benzimidazole derivative ligands (L1 and L3) and a quinoxaline derivative ligand (L2). Furthermore, the chemical selectivity of the condensation was studied, where the condensation of o-diamino and the aldehyde is more stable and easy to operate. This strategy enriches the synthesis method of MOFs. Additionally, compound 2 containing uncoordinated quinoxaline N atoms showed excellent luminescent sensitivity for Fe3+ detection.

Coligand-directed synthesis of five Co(II)/Ni(II) coordination polymers with a neutral tetradentate ligand: syntheses, crystal structures, and properties.

The solvothermal reactions of 1,1'-oxybis[3,5-di-4-pyridine]-benzene (L) and transition metal cations (Co and Ni) afford five novel coordination polymers in the presence of flexible bridging ligands (4,4'-H2nba = 4,4'-dicarboxydiphenylamine, H2cam = d-camphoric acid, 4,4'-H2sdb = 4,4'-sulfonyldibenzoic acid, H2chdc = 1,4-trans-cyclohexanedicarboxylic acid), namely {[Co2L2(OH)2(nba)]·2DMF}n (), {[CoL(cam)(H2O)]}n (), {[Co3(L)(4,4'-sdb)3(H2O)]·1.5CH3CN·4H2O}n (), {[Ni3(L)(4,4'-sdb)3(H2O)]·1.5CH3CN·4H2O}n (), and {[Ni2L2(chdc)2(H2O)2]·(H2O)3}n () (DMF = N,N-dimethylformamide). Their structures have been determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectroscopy, and powder X-ray diffraction. Complex reveals a 2-fold interpenetrating three-dimensional (3D) framework with the Schläfli symbol {4·8·10(4)}{4·8·10} topology. Compound crystallizes in the achiral space group with the d-camphorate ligand racemized. Compounds and reveal similar structure with the {3·4(4)·6}{3(2)·4(8)·5(9)·6(9)} topology based on a linear trinuclear building block M3(OOCR)6 (M = Co(ii) or Ni(ii)). Compound is a wavy sheet, where both carboxylate and L ligands act as bidentate ligands. Moreover, UV-Visible absorption spectra of complexes , and the magnetic properties of have been investigated.