Dimer Formation Research Articles

Predicting a Stable Dimeric Form of the PD1-PDL1 Complex: Implications for Understanding the PD1 Activation Mechanism.

The activation of T cells is typically accompanied by inhibitory mechanisms within which the programmed cell death (PD1) receptor stands out. Upon binding the ligands PDL1 and PDL2, PD1 drives T cells to an unresponsive state called exhaustion, characterized by a markedly decreased capacity to exert effector functions. For this reason, PD1 has become one of the most important targets in cancer immunotherapy. Despite the numerous studies about PD1 signaling modulation, how the PD1 signaling is activated upon the ligands' binding remains an open question. Several experimental facts suggest that the activation of the PD1-PLD1 pathway depends on the interaction with an unknown partner at the cellular membrane. In this work, we investigate the possibility that the target of PD1-PDL1 is the same PD1-PDL1 complex. We combined molecular docking with molecular dynamics and umbrella sampling simulations to explore different binding modes and assess the complexes' stability. We predicted a stable dimeric form of the extracellular domains of the PD1-PDL1 complex. This dimeric complex has an affinity comparable to the PD1-PDL1 interaction and resembles the form of a linear lattice. We proposed a new model for PD1 activation where the PD1-PDL1 dimeric form could facilitate the interaction of the intracellular domains of PD1 and the further binding and activation of the SHP2 phosphatase. This model might explain the inhibitory effect of anti-PD1/PDL1 antibodies through the prevention of the formation of the PD1-PDL1 dimers and, subsequently, the abrogation of the SHP2 phosphatase activation.

Reversible Light-Induced Dimerization of Secondary Face Azobenzene-Functionalized β-Cyclodextrin Derivatives.

β-cyclodextrin (βCyD) derivatives equipped with aromatic appendages at the secondary face exhibit tailorable self-assembling capabilities. The aromatic modules can participate in inclusion phenomena and/or aromatic-aromatic interactions. Supramolecular species can thus form that, at their turn, can engage in further co-assembling with third components in a highly regulated manner; the design of nonviral gene delivery systems is an illustrative example. Endowing such systems with stimuli responsiveness while keeping diastereomeric purity and a low synthetic effort is a highly wanted advancement. Here, we show that an azobenzene moiety can be "clicked" to a single secondary O-2 position of βCyD affording 1,2,3-triazole-linked βCyD-azobenzene derivatives that undergo reversible light-controlled self-organization into dimers where the monomer components face their secondary rims. Their photoswitching and supramolecular properties have been thoroughly characterized by UV-vis absorption, induced circular dichroism, nuclear magnetic resonance, and computational techniques. As model processes, the formation of inclusion complexes between a water-soluble triazolylazobenzene derivative and βCyD as well as the assembly of native βCyD/βCyD-azobenzene derivative heterodimers have been investigated in parallel. The stability of the host-guest supramolecules has been challenged against the competitor guest adamantylamine and the decrease of the medium polarity using methanol-water mixtures. The collective data support that the E-configured βCyD-azobenzene derivatives, in aqueous solution, form dimers stabilized by the interplay of aromatic-aromatic and aromatic-βCyD cavity interactions after partial reciprocal inclusion. Photoswitching to the Z-isomer disrupts the dimers into monomeric species, offering opportunity for the spatiotemporal control of the organizational status by light.

Repression of autocrine pheromone signaling leads to fusaric acid over-production

Fusaric acid (FA), a picolinic acid derivative, is a natural substance produced by a wide variety of fungal plant pathogens belonging to the Fusarium genus. As a metabolite, fusaric acid exerts several biological activities including metal chelation, electrolyte leakage, repression of ATP synthesis, and direct toxicity on plants, animals and bacteria. Prior studies on the structure of fusaric acid revealed a co-crystal dimeric adduct between FA and 9,10-dehydrofusaric acid. During an ongoing search for signaling genes differentially regulating FA production in the fungal pathogen Fusarium oxysporum (Fo), we found that mutants lacking pheromone expression have an increased production of FA compared to the wild type strain. Noteworthy, crystallographic analysis of FA extracted from Fo culture supernatants showed that crystals are formed by a dimeric form of two FA molecules (1:1 molar stoichiometry). Overall, our results suggest that pheromone signaling in Fo is required to regulate the synthesis of fusaric acid.

Hexacoordinated MIV (M=Ti, Zr, Hf) Tetrachlorido Complexes with Chelating Dithienylethane Based 1,2 Diketone Ligand – π‐Conjugation as Decisive Factor for Axial Chirality Mode

Abstract1,2‐bis(2,5‐dimethylthiophen‐3‐yl)ethane‐1,2‐dione (1, DTEthane) reacts with MCl4 metal precursors of group four (M=Ti, Zr, Hf) via coordination of the carbonyl groups. The molecular structure of complex 2–4 were determined in scXRD studies in the solid state and characterized by means of multi‐nuclear and multi‐dimensional NMR spectroscopy in solution. While the resulting titanium complex [TiCl4(DTEthane)] 2 shows a monomeric structure, where 1 binds in a bidentate fashion, complexes with a Zr (3) and Hf (4) center have dimeric scaffolds in which the ligands adopt a bridging mode. Quantum chemical calculations using density functional theory (G16, B97D3/def2‐TZVP) were used to evaluate the general trend of dimer formation (Ti<Zr<Hf). The molecular structures derived from both scXRD and the DFT optimized structures reveal the carbonyl groups in conjugation with the adjacent thiophene substituent. As a result, they are coplanar and rotation about the two C−C axes (C1−C7; C8−C9) is restricted allowing for only one chiral axis along C7−C8. This gains special importance with respect to previously described complexes carrying the closely related 1,2‐endiolato ligand (1,2‐bis(2,5‐dimethylthiophen‐3‐yl)ethene‐1,2‐diolate), in which no coplanarity of the thiophene rings to their neighboring metallacycle was observed allowing for two chiral axes. Noteworthy, further DFT calculations addressing the pathway of racemization found transition states, which are characterized by contrary rotations of both thiophene rings and a loss of conjugation rather than a direct rotation around the axis C7−C8.

DESAIN PRIMER SECARA IN SILICO UNTUK AMPLIFIKASI GEN tcdA BAKTERI CLOSTRIDIUM DEFFILCILE

Antibiotics are drugs used to fight infections caused by bacteria. C. difficile bacteria is a bacterium that causes Clostridium difficile infection (ICD). Toxin A of C. difficile bacteria is exotoxin A (tcdA) which is a virulence factor that causes disease. Toxin A can damage the intestinal mucosa and cause bleeding. The cost of examining and treating patients with AAD and PMC is very high, so the dosage must be determined correctly. Laboratory tests function to determine the presence or absence of an ICD. The discovery of specific biomarkers is a discovery priority to improve the quality of laboratory tests. Specific primary design is an important step in all types of laboratory examination methods, one of which is molecular examination by PCR. The primary design must have specific properties so as to be efficient at target amplification. This study aims to obtain a primer design that can be used to limit the amplification area of the TcdA gene in silico. This study used a literature study from the NCBI genbank to obtain the tcdA gene sequence of C. defficile bacteria with accession number DQ902560.1. The tcdA gene sequence of C. difficile bacteria was analyzed using Primer3Plus to determine whether there is hairpin and dimer formation. Furthermore, identification was carried out using web-based in silico PCR to determine the number of amplicon and visualization on the electrophoretic gel. The level of tcdA gene homology in the species group in the BLAST test. The results showed that the best primer design for in silico detection of the tcdA gene of C. difficile was the forward primer 5'-GCAGATGCCAAGAGACACAC-3' and the reverse primer 3'-GCAGATGCCAAGACACACAC-5'. The primary design is able to amplify the tcdA gene region with a size of 247 amplicons.

Raman Scattering Spectra and DFT Computational Analyzes of Intermolecular Interactions in Trifluoroacetic and Its Solutions

In this work, the mechanisms of molecular clusters formation in liquid trifluoroacetic acid were studied using Raman scattering spectra in different solutions. The polarized components of Raman scattering spectra corresponding of the C=O, O–H stretching bands of pure trifluoroacetic acid consist of three broad bands at 1734, 1754, and 1800 cm−1 with different depolarization ratios. When the acid is strongly dissolved in acetonitrile, the 1800 cm−1 spectral band belonging to the C=O band remains. The intermolecular interactions in the formation of trifluoroacetic acid monomer, dimer, and trimer, as well as clusters with water [CF3COOH + (H2O)n, n = 1–7] and acetonitrile [CF3COOH + (CH3CN)n, n = 1–2] molecules, were analysed using the density functional theory (DFT) method.

A green yttrium extraction system containing naphthenic acid, trioctyl/decylamine and isopropanol

Yttrium extraction usually produces waste water and suffers from difficulty in phase separation when using saponified naphthenic acid as the extractant. Herein, a non-saponified mixed extraction system containing naphthenic acid, trioctyl/decylamine and modifier was developed for yttrium extraction. Unlike the traditional saponified naphthenic acid system using long chain alcohol as the modifier, short chain alcohol of isopropanol was introduced into the extraction system for the first time. When using 20 vol% naphthenic acid, 40 vol% trioctyl/decylamine, 10 vol% sec-octyl alcohol and 25 vol% isopropanol diluted in 5 vol% n-hexane as extractant, a high yttrium extraction efficiency of above 60% could be obtained within a short phase separation time of ∼5 min. The yttrium separation from other rare earth elements could be achieved through two steps of LaCePrNdY/GdSmEuTbDyHoErTmLuYb grouping extraction followed by LaCePrNd/Y separation. Trioctyl/decylamine, sec-octyl alcohol and isopropanol showed the synergistic extraction effect with naphthenic acid, among which isopropanol was the strongest, followed by trioctyl/decylamine and sec-octyl alcohol. Trioctyl/decylamine could extract H+ produced from naphthenic acid, and isopropanol and/or sec-octyl alcohol could bond with naphthenic acid via hydrogen-bond interaction to prevent the formation of naphthenic acid dimers, leading to more coordination sites exposed for yttrium extraction. Furthermore, isopropanol and/or sec-octyl alcohol participated in the coordination in the extracted organic compound. The combination of the above three action had great contribution to the high extraction efficiency and the rapid phase separation. There was no waste water produced during extraction. Therefore, the proposed mixed system is a green and efficient system for yttrium extraction.

Solvent-induced reversible transformation between monomer-Ag32 and dimer-(Ag32)2 nanoclusters

The controllable transformation of metal nanoclusters remains highly desirable for the preparation of new clusters with novel structures and the elucidation of cluster conversion mechanisms. Here, we present the reversible transformation between two high-nuclearity silver cluster homologs, Ag32S3(StBu)16(CF3COO)9(CH3CN)4(NO3) (abbreviated as monomer-Ag32) and [Ag32S3(StBu)16(CF3COO)9(CH3CN)(NO3)]2 (abbreviated as dimer-(Ag32)2). Triggered by the solvent effect, the reversible conversion between monomer-Ag32 and dimer-(Ag32)2 nanoclusters has been accomplished. For dimer-(Ag32)2, two CF3COO− linkers were bound onto the symmetrical edges of adjacent Ag32 subunits, giving rise to the dimeric existence form of the final cluster. The optical properties, including optical absorptions and emissions, of the cluster monomer and dimer were then compared. This work offered an interesting case for constructing self-assembled cluster structures with the assistance of certain solvents and multidentate ligands.

Discovery of dual inhibitors of pan‐RAF and VEGFR2

AbstractColorectal cancer is among the most common and lethal malignancies globally, with K‐Ras mutations found in about 45% of colorectal cancer patients. Early‐stage BRAF‐specific inhibitors have been developed to prevent aberrant activation of RAS/RAF/MEK/ERK signaling caused by K‐Ras mutation, however, these BRAF‐specific inhibitors lead to RAF dimer formation and paradoxical CRAF activation. Consequently, there is a need to develop pan‐RAF inhibitors. In addition, it was reported that the inhibition of vascular endothelial growth factor receptor 2 (VEGFR2) is crucial for the treatment of colorectal cancer. In this study, we designed and synthesized 94 N‐(phenyl)‐3‐(9H‐purin‐6‐yl)pyridine‐2‐amine derivatives, and discovered that N‐(5‐(3‐(9H‐purin‐6‐yl)pyridin‐2‐ylamino)‐2‐fluorophenyl)‐3‐(trifluoromethyl)benzamide (15h), 3‐(2‐cyanopropan‐2‐yl)benzamide derivative 16h, and 3,5‐bis(trifluoromethyl) benzamide derivative 17ab are the most potent dual inhibitors against LS513 (GI50 = 0.08, 0.2, and 0.3 μM, respectively) and VEGFR2 (IC50 = 0.01, 0.004, and 0.01 μM, respectively). These compounds are excellent preclinical candidates for the treatment of K‐Ras mutated colorectal cancer.

Oridonin inhibits the occurrence and development of colorectal cancer by reversing the Warburg effect via reducing PKM2 dimer formation and preventing its entry into the nucleus

BackgroundThe Warburg effect is prevalent in human cancer. Oridonin (ORI) has excellent anticancer effects, but its exact anticancer mechanism is still unclear. MethodsCCK8, EdU, and flow cytometry assay were performed to detect the effect of ORI on cell viability, proliferation and apoptosis, respectively. RNA-seq was carried out to search the underlying mechanisms. Total PKM2, dimeric PKM2, nuclear PKM2 was detected by Western blot. The epidermal growth factor receptor/extracellular signal regulated kinase (EGFR/ERK) signaling was assayed. The binding ability of Importin-α5 to PKM2 was performed by Co-IP experiments. The effect of ORI combined with cysteine (Cys) or fructose-1, 6-diphosphate (FDP) on cancer cells was detected. Mouse xenograft model was established to confirm the molecular mechanisms in vivo. ResultsORI inhibited viability, proliferation and promoted apoptosis of CRC cells. RNA-seq revealed ORI attenuated the Warburg effect in cancer cells. ORI reduced dimeric PKM2 and prevented it from entering the nucleus. ORI did not affect the EGFR/ERK signaling, but reduced Importin-α5 binding to the PKM2 dimer. Cys or FDP reversed or enhanced the effect of ORI. Animal model assay confirmed the molecular mechanisms in vivo. ConclusionsOur study first shows that ORI could have anticancer activity by inhibiting the Warburg effect as a novel activator of PKM2.

Physicochemical properties characterizing interactions of streptomycin and neomycin with glucose, sucrose and NaCl in aqueous solution: Biophysical insights

In this study we investigated intermolecular interactions of drugs streptomycin and neomycin in the aqueous solution, glucose, sucrose and NaCl to understand the effect of different types of co-solute on the medication. Physicochemical characterization in terms of thermodynamic signatures help in understanding interaction mode of the drug with co-solute molecules. In order to estimate the physicochemical properties we have used ITC (Isothermal Titration Calorimeter), densimeter and UV–visible spectrophotometer techniques. The apparent molar properties of volume and adiabatic compression were found decrease with rise in molality of the drug and increase with rise in temperature. The standard partial molar quantities on volume (V2,m0) and adiabatic compression (Ks,2,m0) of streptomycin were found to be more than that of neomycin in aqueous and mixed aqueous solution. The standard partial molar quantities of transfer for volume (ΔtrV2,m0) and adiabatic compression (ΔtrKs,2,m0) of drug from water to mixed aqueous solutions were found to be positive which suggests ion-ion, ion-hydrophilic or hydrophilic-hydrophilic group interactions dominant over ion-hydrophobic and hydrophobic-hydrophobic group interactions. The exothermic heat supports occurrence of such type of interactions. Absorption maxima and absorbance values were higher in case of aqueous streptomycin than neomycin as former drug was in its dimeric form which suggests the significance of π conjugated system. The values of ΔtrV02,m, ΔtrK0s,2,m and ΔtrHm0 for streptomycin in the presence of aqueous co-solutes were found to be higher than that of neomycin. Partial molar expansion (E20) and expansivity coefficient (α2) values were found to be lesser in case of aqueous streptomycin than that of neomycin.

Investigating trimethylphosphine oxide interactions with Brønsted and Lewis acid sites in zeolites: A comparative solid-state NMR study of wet-phase and gas-phase adsorption techniques

This study examines the differences in using two primary methods for adsorbing trimethylphosphine oxide (TMPO) onto acid catalysts and their influence on the NMR spectra of TMPO-loaded zeolites. The findings show that TMPO molecules interact with both Brønsted and Lewis acid sites, and that the amount of (TMPO)2H+ dimers formed increases with the amount of TMPO added. The use of dichloromethane as a solvent inhibits the formation of dimers and crystalline TMPO but may lead to inaccurate estimations of acid site strength and quantification due to interactions with residual solvent molecules. The gas-phase method is preferred for adsorbing TMPO onto zeolites, but caution is needed to avoid forming a high number of dimers that ca pose challenges in the interpretation of the NMR spectra.

Detection of Arc/Arg3.1 oligomers in rat brain: constitutive and synaptic activity-evoked dimer expression in vivo.

The immediate early gene product activity-regulated cytoskeleton-associated protein (Arc or Arg3.1) is a major regulator of long-term synaptic plasticity with critical roles in postnatal cortical development and memory formation. However, the molecular basis of Arc function is undefined. Arc is a hub protein with interaction partners in the postsynaptic neuronal compartment and nucleus. Previous in vitro biochemical and biophysical analysis of purified recombinant Arc showed formation of low-order oligomers and larger particles including retrovirus-like capsids. Here, we provide evidence for naturally occurring Arc oligomers in the mammalian brain. Using in situ protein crosslinking to trap weak Arc-Arc interactions, we identified in various preparations a prominent Arc immunoreactive band on SDS-PAGE of molecular mass corresponding to a dimer. While putative trimers, tetramers and heavier Arc species were detected, they were of lower abundance. Stimulus-evoked induction of Arc expression and dimer formation was first demonstrated in SH-SY5Y neuroblastoma cells treated with the muscarinic cholinergic agonist, carbachol, and in primary cortical neuronal cultures treated with brain-derived neurotrophic factor (BDNF). In the dentate gyrus (DG) of adult anesthetized rats, induction of long-term potentiation (LTP) by high-frequency stimulation (HFS) of medial perforant synapses or by brief intrahippocampal infusion of BDNF led to a massive increase in Arc dimer expression. Arc immunoprecipitation of crosslinked DG tissue showed enhanced dimer expression during 4 h of LTP maintenance. Mass spectrometric proteomic analysis of immunoprecipitated, gel-excised bands corroborated detection of Arc dimer. Furthermore, Arc dimer was constitutively expressed in naïve cortical, hippocampal and DG tissue, with the lowest levels in the DG. Taken together the results implicate Arc dimer as the predominant low-oligomeric form in mammalian brain, exhibiting regional differences in its constitutive expression and enhanced synaptic activity-evoked expression in LTP.

Kinetic Formation of Pt-Pt Dimers of Cationic and Neutral Platinum(II) Complexes under Rapid Freeze Conditions in Solution.

We report the formation of M-M dimers (M = Pt or Pd) of cationic [M(dpb)(CH3CN)]+ [dpbH = 1,3-di(2-pyridyl)benzene] and neutral [M(dpb)Cl] complexes resulting from the rapid freezing of solutions. Dimers based on M-M dz2 overlap were found to preferentially form rather than the thermodynamically favored head-to-tail π-stacking structures typically observed in the crystalline state. Kinetic dimers in glassy frozen solutions generated broad metal-metal-to-ligand charge-transfer emissions within the range of 600-800 nm at 77 K. These emissions were red-shifted relative to monomer emissions. As expected, the degree of aggregation of these complexes was affected by the concentration in each solution. Photoexcitation evidently accelerated Pt-Pt dimerization even at ambient temperature. Electrostatic attraction between [Pt(dpb)Cl]+ and [Pt(dpb)Cl]- ions resulting from disproportionation due to photoinduced electron transfer is thought to have driven excimer formation. [Pt(dpb)(CH3CN)]OTf (OTf- = trifluoromethanesulfonate ion) and its Pd(II) analogue were determined to have isostructural crystals, but a Pd-Pd stacked polymorph was not observed and the photophysics of the two complexes are evidently different.

Odd–even disparity in the population of slipped hairpins in RNA repeat sequences with implications for phase separation

Low-complexity nucleotide repeat sequences, which are implicated in several neurological disorders, undergo liquid-liquid phase separation (LLPS) provided the number of repeat units, n, exceeds a critical value. Here, we establish a link between the folding landscapes of the monomers of trinucleotide repeats and their propensity to self-associate. Simulations using a coarse-grained Self-Organized Polymer (SOP) model for (CAG)n repeats in monovalent salt solutions reproduce experimentally measured melting temperatures, which are available only for small n. By extending the simulations to large n, we show that the free-energy gap, ΔGS, between the ground state (GS) and slipped hairpin (SH) states is a predictor of aggregation propensity. The GS for even n is a perfect hairpin (PH), whereas it is a SH when n is odd. The value of ΔGS (zero for odd n) is larger for even n than for odd n. As a result, the rate of dimer formation is slower in (CAG)30 relative to (CAG)31, thus linking ΔGS to RNA-RNA association. The yield of the dimer decreases dramatically, compared to the wild type, in mutant sequences in which the population of the SH decreases substantially. Association between RNA chains is preceded by a transition to the SH even if the GS is a PH. The finding that the excitation spectrum-which depends on the exact sequence, n, and ionic conditions-is a predictor of self-association should also hold for other RNAs (mRNA for example) that undergo LLPS.

PAXX binding to the NHEJ machinery explains functional redundancy with XLF.

Nonhomologous end joining is a critical mechanism that repairs DNA double-strand breaks in human cells. In this work, we address the structural and functional role of the accessory protein PAXX [paralog of x-ray repair cross-complementing protein 4 (XRCC4) and XRCC4-like factor (XLF)] in this mechanism. Here, we report high-resolution cryo-electron microscopy (cryo-EM) and x-ray crystallography structures of the PAXX C-terminal Ku-binding motif bound to Ku70/80 and cryo-EM structures of PAXX bound to two alternate DNA-dependent protein kinase (DNA-PK) end-bridging dimers, mediated by either Ku80 or XLF. We identify residues critical for the Ku70/PAXX interaction in vitro and in cells. We demonstrate that PAXX and XLF can bind simultaneously to the Ku heterodimer and act as structural bridges in alternate forms of DNA-PK dimers. Last, we show that engagement of both proteins provides a complementary advantage for DNA end synapsis and end joining in cells.

Speciation and Photoluminescent Properties of a 2,6‐Bis(pyrrol‐2‐yl)pyridine in Three Protonation States

Abstract2,6‐Bis(pyrrol‐2‐yl)pyridines are important building blocks for supramolecular assemblies and photoluminescent main group and transition metal compounds. Sterically encumbered 2,6‐bis(5‐(2,4,6‐trimethylphenyl)‐3‐phenyl‐1H‐pyrrol‐2‐yl)pyridine, H2MesPDPPh, can adopt monomeric and dimeric structures in the solid state and in solution, controlled by competing inter‐ and intramolecular hydrogen bonds. Deprotonation in the presence of lithium cations provides Li2MesPDPPh, which can be isolated in monomeric and dimeric forms depending on solvent polarity. Protonation of H2MesPDPPh disrupts intramolecular hydrogen bonding and provides the monomeric pyridinium salt [H3MesPDPPh]Cl. Independent of solvent polarity, all three derivatives exhibit intense fluorescence in solution. The absorption and emission spectra are highly sensitive to the level of protonation, which can be rationalized by the effects of (de)protonation on the HOMO and LUMO of the tricyclic π‐system.

Engineered organotin(IV) and vanadium(V) derivatives with distinct coordination modes and luminescent properties for the efficient detection and quantification of permanganate ions.

The distinction in coordination modes of metal complexes leads to their versatile structural features and unique properties. Here, we report two tetradentate Schiff base ligands (H2L1 and H2L2) bearing N2O2 donor sets, tactically selected to provide distinct coordination modes with different metal ions. The ligands were utilized to synthesize their organotin(IV) (1-4) and vanadium(V) (5) derivatives. The synthesized compounds were characterized using elemental analysis, FT-IR spectroscopy, multi-nuclei NMR (1H, 13C, and 119Sn) spectroscopy, mass spectrometry, and single-crystal X-ray diffraction. The organotin(IV) derivatives (1-4) displayed hepta-coordination around both the Sn centres as they were achieved in their dimeric form. Contrariwise, the vanadium(V) compound (5) was isolated as a mononuclear entity exhibiting penta-coordinated geometry around the vanadium centre. The variation in the coordination modes was evident in their UV-vis and fluorescence spectra. The organotin(IV) compounds (1-4) exhibited a strong emission band centred at 468nm when excited at a wavelength of 360nm whereas the vanadium(V) (5) derivative displayed poor fluorogenic response. Compound 1 was further explored for the fluorogenic chemo-sensing of permanganate ions (MnO4-) amongst various anions by quenching response. A detailed investigation of the recognition of permanganate ions was accomplished by spectrofluorometric, spectroscopic (119Sn NMR), mass spectrometric, and computational studies.

Non-amplification on-spot identifying the sex of dioecious kiwi plants by a portable Raman device.

The kiwi plant is dioecious, and its sex is generally identified from flower morphology at blossoming, which takes several years. It is quite necessary but challenging to on-spot identify the plant sex in juvenile stage. Here the target DNA was obtained by screening the Friendly boy (FrBy) gene which is sex-related for different kiwi plant species. Its complementary sequence was divided into two parts as primer DNA and further attached to different gold nanoparticles (GNPs). The connection between target DNA and primer DNA will promote the formation of plasmonic dimers. Dark field microscopy (DFM) can distinguish particles in different aggregation states. Various conditions were optimized based on the standard of increasing the proportion of dimers while reducing that of large aggregates. Furthermore, two Raman reporters (RR) are separately labeled on the nanoprobes, and the plasmonic dimers lead to a tremendous Raman enhancement of two reporters located at the dimer nanogap. Double-blind tests proved the feasibility of this method on the actual samples of kiwi plant leaves. Our SERS method is sensitive, specific, and reliable for rapid sex identification analysis at the kiwi seeding stage, with great promise for decision-making in field management.

The Anion Impact on Dimensionality of Cadmium(II) Complexes with Nicotinamide

Three novel cadmium(II) coordination compounds, the dimeric [Cd(CH3COO)2(nia)2]2 (1), the polymeric {[Cd(nia)4](ClO4)2}n (2), and the monomeric [Cd(H2O)3(nia)3](ClO4)2·nia (3), were prepared in the reactions of the nicotinamide (pyridine-3-carboxamide, nia) with the corresponding cadmium(II) salts. All prepared compounds were characterized by elemental analyses, FT-IR spectroscopy, TGA/DTA, and single crystal X-ray analysis. The impact of anions (acetate, perchlorate) and solvent used on the dimensionality of cadmium(II) complexes and the cadmium(II) coordination environment was investigated. The bridging capabilities of acetate ions enabled the formation of dimers in the crystal structure of 1. It was shown that the dimensionality of perchlorate complexes depends on the solvent used. The coordination polymer 2 is isolated from an ethanol solution, while monomeric compound 3 was obtained by using a water/ethanol mixture as a solvent. The pentagonal-bipyramidal coordination of cadmium(II) was found in the presence of chelating and bridging acetate ions in 1. In the presence of non-coordinating perchlorate anions in 2 and 3, the coordination geometry of cadmium(II) is found to be octahedral. The supramolecular amide-amide homosynthon R22(8) was preserved in the hydrogen-bonded frameworks of all three compounds.