The advent of SELEX (systematic evolution of ligands by exponential enrichment) technology has shown the ability to evolve artificial ligands with affinity and specificity able to meet growing ...clinical demand for probes that can, for example, distinguish between the target leukemia cells and other cancer cells within the matrix of heterogeneity, which characterizes cancer cells. Though antibodies are the conventional and ideal choice as a molecular recognition tool for many applications, aptamers complement the use of antibodies due to many unique advantages, such as small size, low cost, and facile chemical modification. This Minireview will focus on the novel applications of aptamers and SELEX, as well as opportunities to develop molecular tools able to meet future clinical needs in biomedicine.
Advantages of aptamers and SELEX in diverse research fields are summarized in this Minireview, along with some limitations and possible solutions to them. Furthermore described are future perspectives for aptamer modification with a near‐infinite number of molecular‐modulating elements that will result in more powerful tools in bioscience.
Combining nanomaterials and biomolecule recognition units is promising in developing novel clinic diagnostic and protein analysis techniques. In this work, a highly sensitive and specific ...fluorescence resonance energy transfer (FRET) aptasensor for thrombin detection is developed based on the dye labeled aptamer assembled graphene. Due to the noncovalent assembly between aptamer and graphene, fluorescence quenching of the dye takes place because of FRET. The addition of thrombin leads to the fluorescence recovery due to the formation of quadruplex−thrombin complexes which have weak affinity to graphene and keep the dyes away from graphene surface. Because of the high fluorescence quenching efficiency, unique structure, and electronic properties of graphene, the graphene aptasensor exhibits extraordinarily high sensitivity and excellent specificity in both buffer and blood serum. A detection limit as low as 31.3 pM is obtained based on the graphene FRET aptasensor, which is two orders magnitude lower than those of fluorescent sensors based on carbon nanotubes. The excellent performance of FRET aptasensor based on graphene will also be ascribed to the unique structure and electronic properties of graphene.
Two-dimensional layered semiconductors such as MoS₂ and WSe₂ have attracted considerable interest in recent times. Exploring the full potential of these layered materials requires precise spatial ...modulation of their chemical composition and electronic properties to create well-defined heterostructures. Here, we report the growth of compositionally modulated MoS₂-MoSe₂ and WS₂-WSe₂ lateral heterostructures by in situ modulation of the vapour-phase reactants during growth of these two-dimensional crystals. Raman and photoluminescence mapping studies demonstrate that the resulting heterostructure nanosheets exhibit clear structural and optical modulation. Transmission electron microscopy and elemental mapping studies reveal a single crystalline structure with opposite modulation of sulphur and selenium distributions across the heterostructure interface. Electrical transport studies demonstrate that the WSe₂-WS₂ heterojunctions form lateral p-n diodes and photodiodes, and can be used to create complementary inverters with high voltage gain. Our study is an important advance in the development of layered semiconductor heterostructures, an essential step towards achieving functional electronics and optoelectronics.
Novel Cyclam-functionalized carbon dots for highly sensitive (detection limit: 100nM for Cu2+ and 130nM for S2−) and selective detection of Cu2+ and S2− in water were prepared by surface modification ...of prepared carbon dots. The prepared dual-ion sensor can be reversibly switched for several times by selective addition of adequate Cu2+ or S2−, and exhibited excellent longterm photostability for Cu2+ detection (≥35 days) in aqueous media. More importantly, the CCDs sensor also displayed low cytotoxicity and can be utilized to monitor Cu2+ and S2− level change in live cells.
•The CCDs sensor was prepared by surface modification of prepared carbon dots.•The sensor can selectively sense Cu2+ and S2− in water.•The detection limit of sensor is 100nM for Cu2+ and 130nM for S2−.•The sensor has excellent longterm photostability and low cytotoxicity.•The sensor can realize monitoring of Cu2+ and S2− in live cells.
The detection of copper ion (Cu2+) and sulfide anion (S2−) is of vital importance since the abnormal level of Cu2+ or S2− can lead to many diseases. Herein, a highly sensitive and selective fluorescent sensor, 1,4,8,11-tetraazacyclotetradecane (Cyclam)-functionalized carbon dots (CCDs), has been designed, synthesized and evaluated for Cu2+ and S2−. For this nanoprobe, a specific fluorescence resonance energy transfer (FRET) process can be effectively take place between carbon dots and the surface Cu2+-Cyclam complex, the as-prepared CCDs display high sensitivity (detection limit: 100nM) and selectivity toward Cu2+ among many other metal cations (such as Mg2+, Co2+, Pb2+, Ni2+, Mn2+, Hg2+, Fe2+, Ca2+ and Zn2+) in 100% aqueous solution. Moreover, it is worth to point out that the subsequent addition of S2− can extract Cu2+ from the CCDs-Cu2+ complex and recover the fluorescence of carbon dots, the detection limit for S2− can reach to 130nM in the aqueous medium. And no statistically significant interference was observed among the other 10 anions (HCO3−, SO42−, NO3−, Cl−, CO32−, S2O32−, F−, Br−, HPO4−, ClO4−) for S2− through the study. In addition, the novel type of multifunctional fluorescent sensor has a relatively wide pH range (pH 4–10). At the same time, it exhibited remarkable longterm fluorescence stability (≥35 days) for Cu2+ detection. In addition, this nanoprobe exhibits very low cytotoxicity and can easily permeate the cell membrane and realize Cu2+ and S2− monitoring and imaging in live cells. Therefore, this novel approach can be used in various fields, such as the detection of multiplex analytes in biological applications and environment, and it will reveal great application prospects.
Protein-dominant cellular processes cannot be fully decoded without precise manipulation of their activity and localization in living cells. Advances in optogenetics have allowed spatiotemporal ...control over cellular proteins with molecular specificity; however, these methods require recombinant expression of fusion proteins, possibly leading to conflicting results. Instead of modifying proteins of interest, in this work, we focus on design of a tunable recognition unit and develop an aptamer-based near-infrared (NIR) light-responsive nanoplatform for manipulating the subcellular localization of specific proteins in their native states. Our results demonstrate that this nanoplatform allows photocontrol over the cytoplasmic-nuclear shuttling behavior of the target RelA protein (a member of the NF-κβ family), enabling regulation of RelA-related signaling pathways. With a modular design, this aptamer-based nanoplatform can be readily extended for the manipulation of different proteins (e.g., lysozyme and p53), holding great potential to develop a variety of label-free protein photoregulation strategies for studying complex biological events.
Graphene material has been widely used for optical sensors owing to its excellent properties, including high-energy transfer efficiency, large surface area, and great biocompatibility. Different ...analytes such as nucleic acids, proteins, and small molecules can be detected by graphene-material-based optical sensors. This review provides a comprehensive discussion of graphene-material-based optical sensors focusing on detection mechanisms and biosensor designs. Challenges and future perspectives for graphene-material-based optical sensors are also presented.
Particulate matter is a component of ambient air pollution that has been linked to millions of annual premature deaths globally
. Assessments of the chronic and acute effects of particulate matter on ...human health tend to be based on mass concentration, with particle size and composition also thought to play a part
. Oxidative potential has been suggested to be one of the many possible drivers of the acute health effects of particulate matter, but the link remains uncertain
. Studies investigating the particulate-matter components that manifest an oxidative activity have yielded conflicting results
. In consequence, there is still much to be learned about the sources of particulate matter that may control the oxidative potential concentration
. Here we use field observations and air-quality modelling to quantify the major primary and secondary sources of particulate matter and of oxidative potential in Europe. We find that secondary inorganic components, crustal material and secondary biogenic organic aerosols control the mass concentration of particulate matter. By contrast, oxidative potential concentration is associated mostly with anthropogenic sources, in particular with fine-mode secondary organic aerosols largely from residential biomass burning and coarse-mode metals from vehicular non-exhaust emissions. Our results suggest that mitigation strategies aimed at reducing the mass concentrations of particulate matter alone may not reduce the oxidative potential concentration. If the oxidative potential can be linked to major health impacts, it may be more effective to control specific sources of particulate matter rather than overall particulate mass.
On the basis of the inhibition of double strand DNA (dsDNA)-templated fluorescent copper nanoparticles (CuNPs) by pyrophosphate (PPi), a novel label-free turn-on fluorescent strategy to detect ...alkaline phosphatase (ALP) under physiological conditions has been developed. This method relies on the strong interaction between PPi and Cu2+, which would hamper the effective formation of fluorescent CuNPs, leading to low fluorescence intensity. The ALP-catalyzed PPi hydrolysis would disable the complexation between Cu2+ and PPi, facilitating the formation of fluorescent CuNPs through the reduction by ascorbate in the presence of dsDNA templates. Thus, the fluorescence intensity was recovered, and the fluorescence enhancement was related to the concentration of ALP. This method is cost-effective and convenient without any labels or complicated operations. The present strategy exhibits a high sensitivity and the turn-on mode provides a high selectivity for the ALP assay. Additionally, the inhibition effect of phosphate on the ALP activity was also studied. The proposed method using a PPi substrate may hold a potential application in diagnosis of ALP-related diseases or evaluation of ALP functions in biological systems.
The design of controllable dynamic systems is vital for the construction of organelle‐like architectures in living cells, but has proven difficult due to the lack of control over defined topological ...transformation of self‐assembled structures. Herein, we report a DNA based dynamic assembly system that achieves lysosomal acidic microenvironment specifically inducing topological transformation from nanoparticles to organelle‐like hydrogel architecture in living cells. Designer DNA nanoparticles are constructed from double‐stranded DNA with cytosine‐rich stick ends (C‐monomer) and are internalized into cells through lysosomal pathway. The lysosomal acidic microenvironment can activate the assembly of DNA monomers, inducing transformation from nanoparticles to micro‐sized organelle‐like hydrogel which could further escape into cytoplasm. We show how the hydrogel regulates cellular behaviors: cytoskeleton is deformed, cell tentacles are significantly shortened, and cell migration is promoted.
Design of controllable dynamic systems to construct organelle‐like architectures is an emerging paradigm for recreating cellular functions and interfering disease process. A dynamic DNA system that achieves lysosomal acidic microenvironment specifically inducing topological transformation from nanoparticles to organelle‐like hydrogel architecture in living cells is reported.
The self‐assembly of sodium dodecyl benzene sulphonate (SDBS) functionalized graphene sheets (GSs) and horseradish peroxidase (HRP) by electrostatic attraction into novel hierarchical nanostructures ...in aqueous solution is reported. Data from scanning electron microscopy, high‐resolution transmission electron microscopy, and X‐ray diffraction demonstrate that the HRP–GSs bionanocomposites feature ordered hierarchical nanostructures with well‐dispersed HRP intercalated between the GSs. UV‐vis and infrared spectra indicate the native structure of HRP is maintained after the assembly, implying good biocompatibility of SDBS‐functionalized GSs. Furthermore, the HRP–GSs composites are utilized for the fabrication of enzyme electrodes (HRP–GSs electrodes). Electrochemical measurements reveal that the resulting HRP–GSs electrodes display high electrocatalytic activity to H2O2 with high sensitivity, wide linear range, low detection limit, and fast amperometric response. These desirable electrochemical performances are attributed to excellent biocompatibility and superb electron transport efficiency of GSs as well as high HRP loading and synergistic catalytic effect of the HRP–GSs bionanocomposites toward H2O2. As graphene can be readily non‐covalently functionalized by “designer” aromatic molecules with different electrostatic properties, the proposed self‐assembly strategy affords a facile and effective platform for the assembly of various biomolecules into hierarchically ordered bionanocomposites in biosensing and biocatalytic applications.
A simple method for assembling graphene sheets with HRP through electrostatic attraction into novel hierarchically ordered nanocomposites is described, and the enzyme electrode with good biocompatibility and excellent electrochemical catalytic performance to H2O2 is fabricated.
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