A MoS2 nanosheet-based CRISPR/Cas12a biosensor for efficient miRNA quantification for acute myocardial infarction

Acute myocardial infarction (AMI) represents the leading cause of cardiovascular death worldwide, and it is thus pivotal to develop effective approaches for the timely detection of AMI markers, especially possessing the characteristics of antibody-free, signal amplification, and manipulation convenience. We herein construct a MoS2 nanosheet-powered CRISPR/Cas12a sensing strategy for sensitive determination of miR-499, a superior AMI biomarker to protein markers. The presence of miR-499 at a trace level is able to induce a significantly enhanced fluorescence signal in a DNA-based molecular engineering platform, which consists of CRISPR/Cas12a enzymatic reactions and MoS2 nanosheet-controllable signal reporting components. The MoS2 nanosheets were characterized by using atomic force microscopy (AFM) and transmission electron microscope (TEM). The detection feasibility was verified by using polyacrylamide gel electrophoresis (PAGE) analysis and fluorescence measurements. The detection limit is determined as 381.78 pM with the linear range from 0.1 ⅹ 10-9 to 13.33 ⅹ 10-9 M in a fast manner (about 30 min). Furthermore, miRNA detection in real human serum is also conducted with desirable recovery rates (89.5 %-97.6 %), which may find potential application for the clinic diagnosis. We describe herein the first example of MoS2 nanosheet-based signal amplified fluorescence sensor for effective detection of AMI-related miRNA.

High-Flux lamellar MoSe2 membranes for efficient dye/salt separation

Membrane-based technology is emerging as an efficient technique for wastewater treatment in recent years. Membranes made up of two-dimensional materials provide high selectivity and water flux compared to conventional polymeric membranes. Herein, we report the synthesis and use of MoSe₂ membrane for dye and drug separation in wastewater, mainly from textile and pharmaceutical industries. The as-prepared MoSe₂ membrane shows ∼ 100% rejection for organic dyes and ciprofloxacin drug with a water flux reaching up to ∼ 900 Lm^-2h^-1bar^-1. Further, the MoSe₂ membrane shows lower NaCl rejection of ∼ 1.9% for the dye/salt mixture. The interlayer spacing in the MoSe₂ membrane allows the water molecules and ions from the salt to pass through freely but restricts the movement of large contaminants. The membrane is stable against the bovine albumin serum fouling with a flux recovery rate of 96%. It also shows good performance even in harsh environments (pH 3-10). To the best of our knowledge, the MoSe₂ membranes were fabricated for the first time for wastewater treatment application. The dye/salt separation performance of the MoSe₂ membrane is significantly better than several other membranes. This work highlights the promising potential for using two-dimensional materials for textile and pharmaceutical wastewater treatment.

Graphene-MoS2 polyfunctional hybrid hydrogels for the healing of transected Achilles tendon

Healing of injured tendon is a major clinical challenge in orthopaedic medicine, due to the poor regenerative potential of this tissue. Two-dimensional nanomaterials, as versatile scaffolds, have shown a great potential to support, trigger and accelerate the tendon regeneration. However, weak mechanical properties, poor functionality and low biocompatibility of these scaffolds as well as post-surgery infections are main drawbacks that limit their development in the higher clinical phases. In this work, a series of hydrogels consisting polyglycerol functionalized reduced graphene oxide (PG), polyglycerol-functionalized molybdenum disulfide (PMoS₂) and PG/PMoS₂ hybrid within the gelatin matrix are formulated in new scaffolds and their ability for the healing of injured Achilles tendon, due to their high mechanical properties, low toxicity, cell proliferation enhancement, and antibacterial activities is investigated. While scaffolds containing PG and PMoS₂ showed a moderate tendon regeneration and anti-inflammatory effect, respectively, their hybridization into PG/PMoS₂ demonstrated a synergistic healing efficiency. Along the same line, an accelerated return of tendon function with low peritendinous adhesion and low cross-sectional area in animal group treated with scaffold containing PG/PMoS₂ was observed. Taking advantage of the high biocompatibility, high strength, straightforward construction and fast tendon regeneration, PG/PMoS₂ can be used as a new scaffold for the future tissue engineering.

Ab initio simulations of black and blue phosphorene functionalised with chemical groups for biomolecule anchoring

Black and blue phosphorene (2D-dimensional allotropes of phosphorus) have shown fascinating electronic, optical, and magnetic properties, with promising technological applications. In this work, we studied the adsorption of amine, hydroxyl, amide, and carboxyl groups onto both black and blue phosphorenes, in order to analyse the effects of biomolecule anchoring on the structural and electronic properties of phosphenes, using density functional simulations. Analyses were carried out of six different configurations for each chemical group functionalised on black and blue phosphorene. We observed that the radicals interacted via a chemisorption regime with the nanostructures, with binding energies that varied from 1.42 to 3.78 eV. The electronic properties showed that the presence of the chemical groups altered the energy gaps for both black and blue phosphorenes, due to a presence of a half-filled level when a single radical was adsorbed. We were able to observe that functionalised two-dimensional phosphorene showed promising characteristics in terms of anchoring molecules, and particularly those of biological interest, due to its high surface area, strong coupling between phosphorene and chemical groups, and the possibility of chemically manipulating radicals.

Sensitive and selective detection of chromium (VI) based on two-dimensional luminescence metal organic framework nanosheets via the mechanism integrating chemical oxidation-reduction and inner filter effect

Two-dimensional luminescence metal organic framework nanosheets (LMOF) named NH₂-CuMOFs were synthesized using Cu (II) nodes coordinated with negatively charged 2-aminoterephthalic acid (NH₂-BDC) via a bottom-up strategy, which were first used as the fluorescent probes for the detection of chromium Cr (VI). The nanosheets possess stable fluorescence with the maximum emission wavelength of 436 nm at excitation of 338 nm that can be effectively quenched by hexavalent chromium Cr (VI). The NH₂-CuMOFs nanosheets show superior advantage over the linker of NH₂-BDC for the excellent selectivity to Cr (Ⅵ) without the interferences of other metal ions. The mechanism investigation suggested that the sensitive detection of Cr (VI) was attributed to the chemical oxidation-reduction (redox) reaction and internal filtration effect (IFE) between Cr (VI) and NH₂-CuMOFs nanosheets. Based on this mechanism, the quantitation of Cr (VI) was realized in the linear range of 0.1-20 μM with a detection limit of 18 nM. Moreover, the detection of Cr (VI) in real samples was also conducted with good recovery. This work provides an optical sensing nanoplatform for heavy metal ions based on two-dimensional LMOFs via a novel mechanism integrating chemical redox reaction and IFE, which may promise broad application prospect for two-dimensional luminescence nanosheets.

Molecular insights into the loading and dynamics of anticancer drugs on silicene and folic acid-conjugated silicene nanosheets: DFT calculation and MD simulation

The adsorption behavior of Anastrozole (ANA) and Melphalan (MEL) anticancer drugs on the surface of silicene nanosheet (SNS) and functionalized SNS with folic acid (FA-SNS) is investigated and compared using the density functional theory (DFT) and molecular dynamics (MD) simulation. The DFT calculation is performed at the M06-2X/6-31G** level to characterize the optimized geometry properties of the designed complexes. The calculated adsorption energies are in the range from -65.59 to -144.23 kJ/mol, indicating the drug absorption on the surface of SNS and FA-SNS is exergonic. The π-π interaction between the drugs and SNS surface is the main driving force in the formation of drug-carriers complexes. The quantum theory of atoms in molecule (QTAIM) results reveal that the interaction of SNS and FA-SNS with both drugs has a non-covalent nature. The natural bond orbital (NBO) analysis shows that the charge is transferred from the drug molecules to carrier in all of the investigated complexes. Furthermore, MD simulations reveal that the contribution of van der Waals energy in drug-carrier interactions is more than electrostatic energy. Also, the obtained results demonstrate that the movement of drug molecules toward the carriers is spontaneous. Our study provides insights into the drug delivery capability of SNS and FA-SNS for the delivery of two drugs (ANA and MEL).Communicated by Ramaswamy H. Sarma.

Recent advances in aptasensors based on graphene and graphene-like nanomaterials

Graphene and graphene-like two-dimensional nanomaterials have aroused tremendous research interest in recent years due to their unique electronic, optical, and mechanical properties associated with their planar structure. Aptamers have exhibited many advantages as molecular recognition elements for sensing devices compared to traditional antibodies. The marriage of two-dimensional nanomaterials and aptamers has emerged many ingenious aptasensing strategies for applications in the fields of clinical diagnosis and food safety. This review highlights current advances in the development and application of two-dimensional nanomaterials-based aptasensors with the focus on two main signal-transducing mechanisms, i.e. electrochemical and optical. A special attention is paid to graphene, a one-atom thick layer of graphite with exceptional properties, representing a fastgrowing field of research. In view of the unique properties of two-dimensional nanostructures and their inherent advantages of synthetic aptamers, we expect that high-performance two-dimensional nanomaterials-based aptasensing devices will find extensive applications in environmental monitoring, biomedical diagnostics, and food safety.