Contribution of Plasmodium immunomics: potential impact for serological testing and surveillance of malaria

Introduction: Plasmodium vivax (Pv) and P. knowlesi account together for a considerable share of the global burden of malaria, along with P. falciparum (Pf). However, inaccurate diagnosis and undetectable asymptomatic/submicroscopic malaria infections remain very challenging. Blood-stage antigens involved in either invasion of red blood cells or sequestration/cytoadherence of parasitized erythrocytes have been immunomics-characterized, and are vital for the detection of malaria incidence.

Areas covered: We review the recent advances in Plasmodium immunomics to discuss serological markers with potential for specific and sensitive diagnosis of malaria. Insights on alternative use of immunomics to assess malaria prevalence are also highlighted. Finally, we provide practical applications of serological markers as diagnostics, with an emphasis on dot immunogold filtration assay which holds promise for malaria diagnosis and epidemiological surveys.

Expert commentary: The approach largely contributes to Pf and Pv research in identifying promising non-orthologous antigens able to detect malaria incidence and to differentiate between past and recent infections. However, further studies to profiling naturally acquired immune responses are expected in order to help discover/validate serological markers of no cross-seroreactivity and guide control interventions. More so, the application of immunomics to knowlesi infections would help validate the recently identified antigens and contribute to the discovery of additional biomarkers of exposure, immunity, or both.     

Superparamagnetic graphene quantum dot as a dual‐modality contrast agent for confocal fluorescence microscopy and magnetomotive optical coherence tomography

A magnetic graphene quantum dot (MGQD) nanoparticle, synthesized by hydrothermally reducing and cutting graphene oxide‐iron oxide sheet, was demonstrated to possess the capabilities of simultaneous confocal fluorescence and magnetomotive optical coherence tomography (MMOCT) imaging. This MGQD shows low toxicity, significant tunable blue fluorescence and superparamagnetism, which can thus be used as a dual‐modality contrast agent for confocal fluorescence microscopy (CFM) and MMOCT. The feasibility of applying MGQD as a tracer of cells is shown by imaging and visualizing MGQD labeled cells using CFM and our in‐house MMOCT. Since MMOCT and CFM can offer anatomical structure and intracellular details, respectively, the MGQD for cell tracking could provide a more comprehensive diagnosis.      

Octa-O-propanoyl-beta-maltose: crystal structure, acyl stacking, related structures, and conformational analysis

The crystal structure of beta-maltose octapropanoate (1) was solved to improve understanding of di-, oligo-, and polysaccharide conformations. The O6 and O6' atoms are in gg and gt orientations, respectively. Extrapolation of the coordinates of the non-reducing residue and observed linkage bond and torsion angles of 1 [Formula: see text] yields a left-handed helix similar to amylose triacetate I. The phi and psi values of 1 are also similar to those of other crystalline, acylated maltose compounds as well as some hydroxyl-bearing molecules. Acylated maltose moieties are often stabilized by stacking of the carbonyl groups and alpha-carbons on O3 and O2' as well as by the exo-anomeric effect. The conformation of 1 is within the 1-kcal/mol contour on a hybrid energy map built with a dielectric constant of 7.5, but corresponds to higher energies on maps made with lower dielectric constants. In one region of phi,psi space, both hydroxyl-bearing and derivatized maltose moieties are found but no inter-residue, intramolecular hydrogen-bonding occurs. In another region, only hydroxyl-bearing molecules crystallize and O2'...O3 hydrogen bonds are always found. In agreement with the energy surfaces, amylose helices extrapolated from available linkage geometries were almost all left-handed.     

Spatio-temporal localization of membrane lipid rafts in mouse oocytes and cleaving preimplantation embryos

We report for the first time the detection of membrane lipid rafts in mouse oocytes and cleaving preimplantation embryos. Cholera toxin β (CTβ), which binds to the raft-enriched ganglioside GM1, was selected to label rafts. In a novel application a Qdot reagent was used to detect CTβ labeling. This is the first reported use of nanocrystals in mammalian embryo imaging. Comparative membrane labeling with CTβ and lipophilic membrane dyes containing saturated or unsaturated aliphatic tails showed that the detection of GM1 in mouse oocytes and embryo membranes was consistent with the identification of cholesterol- and sphingolipid-enriched rafts in the cell membrane. Distribution of the GM1 was compared with the known distribution of non-raft membrane components, and disruption of membrane rafts with detergents confirmed the cholesterol dependence of GM1 on lipid raft labeling. Complementary functional studies showed that cholesterol depletion using methyl-β-cyclodextrin inhibited preimplantation development in culture. Our results show that the membranes of the mouse oocyte and zygote are rich in lipid rafts, with heterogeneous and stage-dependent distribution. In dividing embryos, the rafts were clearly associated with the cleavage furrow. At the morula stage, rafts were also apically enriched in each blastomere. In blastocysts, rafts were detectable in the trophectoderm layer, but could not be detected in the inner cell mass without prior fixation and permeabilization of the embryo. Lipid rafts and their associated proteins are, therefore, spatio-temporally positioned to a play a critical role in preimplantation developmental events.     

Direct electrochemistry of glucose oxidase and electrochemical biosensing of glucose on quantum dots/carbon nanotubes electrodes

Because of their unique chemical, physical and electronic properties, Quantum dots (QDs) and carbon nanotubes (CNTs) are now extremely attractive and important nanomaterials in bioanalytical applications. In this work, CdTe QDs with the size of about 3 nm were prepared and a novel electrochemical biosensing platform of glucose based on CdTe/CNTs electrode was explored. This CdTe/CNTs electrode was prepared by first mixing CdTe QDs, CNTs, Nafion, and glucose oxidase (GOD) in appropriate amounts and then modifying this mixture on the glass carbon electrode (GC). Transmission electron microscopy (TEM) was used to observe the dispersion of CdTe QDs on carbon nanotubes and cyclic voltammetry (CV) was used to investigate the electrochemical behavior of the CdTe/CNTs electrode. A pair of well-defined quasi-reversible redox peaks of glucose oxidase were obtained at the CdTe/CNTs based enzyme electrode by direct electron transfer between the protein and the electrode. The immobilized glucose oxidase could retain bioactivity and catalyze the reduction of dissolved oxygen. Due to the synergy between the CdTe QDs and CNTs, this novel biosensing platform based on QDs/CNTs electrode responded even more sensitively than that based on GC electrode modified by CdTe QDs or CNTs alone. The inexpensive, reliable and sensitive sensing platform based on QDs/CNTs electrode provides wide potential applications in clinical, environmental, and food analysis.     

Production of cross-reactive peptide antibodies against viral capsid proteins of human enterovirus B to apply diagnostic reagent

The coxsackievirus group B (CVB) of the genus Enterovirus and the species human enterovirus B is a nonenveloped virus containing a single-stranded positive-sense RNA genome. Coxsackievirus has icosahedral symmetry and four capsid proteins, VP1, VP2, VP3, and VP4. Specific antibodies against each viral protein are prerequisites for various studies. In this study, we developed seven peptide-derived antibodies directed against coxsackievirus VP1 (NO1-NO5), VP2 (B3), and VP3 (GL3). We developed a type-specific antibody (NO1) and broadly cross-reactive antibodies (NO3 and NO5) to VP1. Anti-VP2 and anti-VP3 antibodies (B3 and GL3, respectively) are also cross-reactive to human enterovirus B such as CVB and echoviruses. Their sensitivities and reactivities are likely to be better than those of the commercial VP1 monoclonal antibody (MAb). The dot-blot analysis also showed that NO5 against VP1 is able to detect less than 1 microg [2x10(6) plaque-forming unit (pfu) of CVB3] of viruses, suggesting that it could be used to develop a diagnostic kit that can directly detect human enterovirus B. The antibodies produced here may allow us to undertake several studies, such as those involving viral trafficking, expression kinetics, and the roles of viral proteins in infection, and the development of diagnostic kits.     

Fluorescent quantum dots: An insight on synthesis and potential biological application as drug carrier in cancer

Quantum dots (QDs) are nanocrystals of semiconducting material possessing quantum mechanical characteristics with capability to get conjugated with drug moieties. The particle size of QDs varies from 2 to 10 nm and can radiate a wide range of colours depending upon their size. Their wide and diverse usage of QDs across the world is due to their adaptable properties like large quantum yield, photostability, and adjustable emission spectrum. QDs are nanomaterials with inherent electrical characteristics that can be used as drug carrier vehicle and as a diagnostic in the field of nanomedicine. Scientists from various fields are aggressively working for the development of single platform that can sense, can produce a microscopic image and even be used to deliver a therapeutic agent. QDs are the fluorescent nano dots with which the possibilities of the drug delivery to a targeted site and its biomedical imaging can be explored. This review is mainly focused on the different process of synthesis of QDs, their application especially in the areas of malignancies and as a theranostic tool. The attempt is to consolidate the data available for the use of QDs in the biomedical applications.     

Kelsoenethiol and dikelsoenyl ether,two unique kelsoane-type sesquiterpenes,from the Formosan soft coral Nephthea erecta

Two new kelsoane-type sesquiterpenes, namely kelsoenethiol (1) and dikelsoenyl ether (2), were obtained from the Formosan soft coral Nephthea erecta. Their structures were elucidated through extensive spectroscopic analyses, ESI orbitrap mass and quantum chemical calculations (QCC). The cytotoxicity against A-459 (human lung carcinoma), P-388 (mouse lymphocytic leukemia), and HT-29 (human colon adenocarcinoma) cancer cell lines of 1 and 2 was evaluated in vitro. Compound 1 showed cytotoxicity against P-388 and HT-29 cells with ED_50s of 1.3 and 1.8 μg/mL, respectively.     

量子点免疫层析快速定量检测HCG

近年来,量子点以其独特的光学性质被广泛应用到医学检测上.血清中人绒毛膜促性腺激素(HCG)的含量是诊断早期妊娠的常用指标,也可用于异常妊娠性疾病的早期发现和鉴别诊断.本文采用超声乳化法制备了高质量的亲水性量子点,并将其与免疫层析试纸条技术相结合,在此基础上自主研发了用于试纸条检测的量子点免疫荧光检测仪,对血清中HCG的含量进行了高灵敏度的快速定量检测.结果表明,对于血清中的HCG含量检测,最优检测条件为加样体积50μl,反应时间15 min,检测的灵敏度达到0.85 U/L,高于商品化的胶体金试纸条.这种检测技术简单、快速、灵敏,有望在其他蛋白质类标志物的检测中得到广泛应用.     

A hot start alternative for high-fidelity DNA polymerase amplification mediated by quantum dots

Quantum dots （QDs） are of great interest due to their unique chemical and physical properties. Recently, a hot start （HS） polymerase chain reaction （PCR） amplification performance based on QDs with a high-fidelity Pfu DNA polymerase has been reported. However, whether QDs can trigger HS effects with other high-fidelity or conventional DNA polymerases is yet to be understood. In the present study, we studied the QD-triggered HS effects with four high-fidelity and three conventional DNA polymerases, and the HS effect comparisons among them were also made. It was found that QDs could trigger a distinct HS PCR amplification performance with all the four tested high,fidelity DNA polymerases, and specific target DNA could be well amplified even if the PCR mixture was preincubated for 2 h at 50℃. On the contrary, the HS effects were not prominent with all the three conventional Taq DNA polymerases. Specifically, the fidelity of Pfu is not sacrificed in the presence of QDs, even after a 1 h pre-incu- bation at 50℃ before PCR. Furthermore, the electrophoresis results preliminarily demonstrated that QDs prefer to adsorb high-fidelity polymerases rather than conventional ones, which might result in the QD-triggered HS effects on PCR performance by using high-fidelity DNA poly- merases.