Ali Aldalbahi

Bio: Ali Aldalbahi is an academic researcher from King Saud University. The author has contributed to research in topics: Materials science & Carbon nanotube. The author has an hindex of 34, co-authored 215 publications receiving 4091 citations. Previous affiliations of Ali Aldalbahi include University of Wollongong.

Electrochemical detection of nucleic acids, proteins, small molecules and cells using a DNA-nanostructure-based universal biosensing platform

Abstract: The occurrence and prognosis of many complex diseases, such as cancers, is associated with the variation of various molecules, including DNA at the genetic level, RNA at the regulatory level, proteins at the functional level and small molecules at the metabolic level (defined collectively as multilevel molecules). Thus it is highly desirable to develop a single platform for detecting multilevel biomarkers for early-stage diagnosis. Here we report a protocol on DNA-nanostructure-based programmable engineering of the biomolecular recognition interface, which provides a universal electrochemical biosensing platform for the ultrasensitive detection of nucleic acids (DNA/RNA), proteins, small molecules and whole cells. The protocol starts with the synthesis of a series of differentially sized, self-assembled tetrahedral DNA nanostructures (TDNs) with site-specifically modified thiol groups that can be readily anchored on the surface of a gold electrode with high reproducibility. By exploiting the rigid structure, nanoscale addressability and versatile functionality of TDNs, one can tailor the type of biomolecular probes appended on individual TDNs for the detection of specific molecules of interest. Target binding occurring on the gold surface patterned with TDNs is quantitatively translated into electrochemical signals via a coupled enzyme-based catalytic process. This uses a sandwich assay strategy in which biotinylated reporter probes recognize TDN-bound target biomolecules, which then allow binding of horseradish-peroxidase-conjugated avidin (avidin-HRP). Hydrogen peroxide (H2O2) is then reduced by avidin-HRP in the presence of TMB (3,3',5,5'-tetramethylbenzidine) to generate a quantitative electrochemical signal. The time range for the entire protocol is ∼1 d, whereas the detection process takes ∼30 min to 3 h.

Golden single-atomic-site platinum electrocatalysts

Abstract: Bimetallic nanoparticles with tailored structures constitute a desirable model system for catalysts, as crucial factors such as geometric and electronic effects can be readily controlled by tailoring the structure and alloy bonding of the catalytic site. Here we report a facile colloidal method to prepare a series of platinum–gold (PtAu) nanoparticles with tailored surface structures and particle diameters on the order of 7 nm. Samples with low Pt content, particularly Pt4Au96, exhibited unprecedented electrocatalytic activity for the oxidation of formic acid. A high forward current density of 3.77 A mgPt−1 was observed for Pt4Au96, a value two orders of magnitude greater than those observed for core–shell structured Pt78Au22 and a commercial Pt nanocatalyst. Extensive structural characterization and theoretical density functional theory simulations of the best-performing catalysts revealed densely packed single-atom Pt surface sites surrounded by Au atoms, which suggests that their superior catalytic activity and selectivity could be attributed to the unique structural and alloy-bonding properties of these single-atomic-site catalysts. Bimetallic nanoparticles with tailored structure constitute a desirable model system for catalysts. PtAu nanoparticles with Pt single-atom surface sites, prepared by a colloidal method, exhibit unprecedented electrocatalytic activity for formic acid oxidation.

Yolk-shell nanostructured Fe3O4@C magnetic nanoparticles with enhanced peroxidase-like activity for label-free colorimetric detection of H2O2 and glucose.

Abstract: Herein, we have developed a simple and facile method to synthesize yolk–shell nanostructured Fe3O4@C nanoparticles (NPs) as a multifunctional biosensing platform for the label-free colorimetric detection of H2O2 and glucose. It was demonstrated that Fe3O4@C yolk–shell nanostructures (YSNs) retained the magnetic properties that can be used for separation and concentration. Also importantly, the Fe3O4@C YSNs exhibited an intrinsic peroxidase-like activity that could quickly catalyze the enzyme substrate in the presence of H2O2 and produce a blue color. Compared to other similar ferric oxide-based NPs with different structures, Fe3O4@C YSNs exhibited greatly enhanced catalytic activities due to their unique structural features. Moreover, steady-state kinetics indicated the catalytic behaviors in agreement with the classic Michaelis–Menten models. Taking advantage of the high catalytic activity, Fe3O4@C YSNs were employed as novel peroxidase mimetics for label-free, rapid, sensitive, and specific colorimetric sensing of H2O2 and glucose, suggesting that Fe3O4@C YSNs have the potential for construction of portable sensors in the application of point-of-care (POC) diagnosis and on-site tests.

DNA Tetrahedral Nanostructure-Based Electrochemical miRNA Biosensor for Simultaneous Detection of Multiple miRNAs in Pancreatic Carcinoma

Abstract: Specific and sensitive biomarker detection is essential to early cancer diagnosis. In this study, we demonstrate an ultrasensitive electrochemical biosensor with the ability to detect multiple pancreatic carcinoma (PC)-related microRNA biomarkers. By employing DNA tetrahedral nanostructure capture probes to enhance the detection sensitivity as well as a disposable 16-channel screen-printed gold electrode (SPGE) detection platform to enhance the detection efficiency, we were able to simultaneously detect four PC-related miRNAs: miRNA21, miRNA155, miRNA196a, and miRNA210. The detection sensitivity reached to as low as 10 fM. We then profiled the serum levels of the four miRNAs for PC patients and healthy individuals with our multiplexing electrochemical biosensor. Through the combined analyses of the four miRNAs, our results showed that PC patients could be discriminated from healthy controls with fairly high sensitivity. This multiplexing PCR-free miRNA detection sensor shows promising applications in earl...

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Synthesis, Properties, and Applications of Hollow Micro-/Nanostructures

Abstract: In this Review, we aim to provide an updated summary of the research related to hollow micro- and nanostructures, covering both their synthesis and their applications. After a brief introduction to the definition and classification of the hollow micro-/nanostructures, we discuss various synthetic strategies that can be grouped into three major categories, including hard templating, soft templating, and self-templating synthesis. For both hard and soft templating strategies, we focus on how different types of templates are generated and then used for creating hollow structures. At the end of each section, the structural and morphological control over the product is discussed. For the self-templating strategy, we survey a number of unconventional synthetic methods, such as surface-protected etching, Ostwald ripening, the Kirkendall effect, and galvanic replacement. We then discuss the unique properties and niche applications of the hollow structures in diverse fields, including micro-/nanocontainers and rea...