Novel Strategy for the Investigation on Chirality Selection of Single-Walled Carbon Nanotubes with DNA by Electrochemical Characterization

A cooperation tale of biomolecules and nanomaterials in nanoscale chiral sensing and separation

The cooperative relationship between biomolecules and nanomaterials makes up a beautiful tale about nanoscale chiral sensing and separation. Biomolecules are considered a fabulous chirality 'donor' to develop chiral sensors and separation systems. Nature has endowed biomolecules with mysterious chirality. Various nanomaterials with specific physicochemical attributes can realize the transmission and amplification of this chirality. We focus on highlighting the advantages of combining biomolecules and nanomaterials in nanoscale chirality. To enhance the sensors' detection sensitivity, novel cooperation approaches between nanomaterials and biomolecules have attracted tremendous attention. Moreover, innovative biomolecule-based nanocomposites possess great importance in developing chiral separation systems with improved assay performance. This review describes the formation of a network based on nanomaterials and biomolecules mainly including DNA, proteins, peptides, amino acids, and polysaccharides. We hope this tale will record the perpetual relation between biomolecules and nanomaterials in nanoscale chirality.

Chiral Materials: Progress, Applications, and Prospects

Chirality is a universal phenomenon in molecular and biological systems, denoting an asymmetric configurational property where an object cannot be superimposed onto its mirror image by any kind of translation or rotation, which is ubiquitous on the scale from neutrinos to spiral galaxies. Chirality plays a very important role in the life system. Many biological molecules in the life body show chirality, such as the "codebook" of the earth's biological diversity-DNA, nucleic acid, etc. Intriguingly, living organisms hierarchically consist of homochiral building blocks, for example, l-amino acids and d-sugars with unknown reason. When molecules with chirality interact with these chiral factors, only one conformation favors the positive development of life, that is, the chiral host environment can only selectively interact with chiral molecules of one of the conformations. The differences in chiral interactions are often manifested by chiral recognition, mutual matching, and interactions with chiral molecules, which means that the stereoselectivity of chiral molecules can produce changes in pharmacodynamics and pathology. Here, the latest investigations are summarized including the construction and applications of chiral materials based on natural small molecules as chiral source, natural biomacromolecules as chiral sources, and the material synthesized by design as a chiral source.

DNA-Mediated Assembly of Carbon Nanomaterials

Carbon nanomaterials (CNMs) have attracted extensive attentions on account of their superior electrical, mechanical, optical, and biological properties. However, the dimensional limit and irregular arrangement have hampered their further application. It is necessary to find an easy, efficient and controllable way to assemble CNMs into well-ordered array. DNA nanotechnology, owning to the advantages of precise programmability, highly structural predictability and spatial addressability, has been widely applied in the assembly of CNMs. Summarizing the progress and achievements in this field will be of great value to related studies. Herein, based on the different dimensions of CNMs containing 0-dimensional (0D) carbon dots (CDs), fullerenes, 1-dimensional (1D) carbon nanotubes (CNTs) and 2-dimensional (2D) graphene, we introduced the conjugation strategies between DNA and CNMs, their different assembly methods and their applications. In addition, we also discuss the existing challenges and future opportunities in the field.

Water Quality Carbon Nanotube-Based Sensors Technological Barriers and Late Research Trends: A Bibliometric Analysis

Water is the key element that defines and individualizes our planet. Relative to body weight, water represents 70% or more for the majority of all species on Earth. Taking care of water as a whole is equivalent with taking care of the entire biodiversity or the whole of humanity itself. Water quality is becoming an increasingly important component of terrestrial life, hence intensive work is being conducted to develop sensors for detecting contaminants and assessing water quality and characteristics. Our bibliometric analysis is focused on water quality sensors based on carbon nanotubes and highlights the most important objectives and achievements of researchers in recent years. Due to important measurement characteristics such as sensitivity and selectivity, or low detection limit and linearity, up to the ability to measure water properties, including detection of heavy metal content or the presence of persistent organic compounds, carbon nanotube (CNT) sensors, taking advantage of available nanotechnologies, are becoming increasingly attractive. The conducted bibliometric analysis creates a visual, more efficient keystones mapping. CNT sensors can be integrated into an inexpensive real-time monitoring data acquisition system as an alternative for classical expensive and time-consuming offline water quality monitoring. The conducted bibliometric analysis reveals all connections and maps all the results in this water quality CNT sensors research field and gives a perspective on the approached methods on this specific type of sensor. Finally, challenges related to integration of other trends that have been used and proven to be valuable in the field of other sensor types and capable to contribute to the development (and outlook) for future new configurations that will undoubtedly emerge are presented.

Probing the adsorption behavior and free energy landscape of single-stranded DNA oligonucleotides on single-layer MoS2with molecular dynamics

Interfacing single-stranded DNA (ssDNA) with 2D transition metal dichalcogenides are important for numerous technological advancements. However, the molecular mechanism of this process, including the nature of intermolecular association and conformational details of the self-assembled hybrids is still not well understood. Here, atomistic molecular dynamics simulation is employed to study the distinct adsorption behavior of ssDNA on a single-layer MoS₂in aqueous environment. The ssDNA sequences [T₁₀, G₁₀, A₁₀, C₁₀, U₁₀, (GT)₅, and (AC)₅] are chosen on the basis that short ssDNA segments can undergo a spontaneous conformational change upon adsorption and allow efficient sampling of the conformational landscape. Differences in hybridization is attributed to the inherent molecular recognition ability of the bases. While the binding appears to be primarily driven by energetically favorable van der Waalsπ-stacking interactions, equilibrium structures are modulated by the ssDNA conformational changes. The poly-purines demonstrate two concurrently competingπ-stacking interactions: nucleobase-nucleobase (intramolecular) and nucleobase-MoS₂(intermolecular). The poly-pyrimidines, on the other hand, reveal enhancedπ-stacking interactions, thereby maximizing the number of contacts. The results provide new molecular-level understanding of ssDNA adsorption on the MoS₂surface and facilitate future studies in design of functional DNA/MoS₂structure-based platforms for DNA sequencing, biosensing (optical, electrochemical, and electronic), and drug delivery.

Ultrasensitive biosensing platform based on luminescence quenching ability of fullerenol quantum dots

An ultrasensitive biosensing platform for DNA and ochratoxin A (OTA) detection is constructed based on the luminescence quenching ability of fullerenol quantum dots (FOQDs) for the first time. As the surface of FOQDs is largely covered by hydroxyl groups, stable colloidal suspension of FOQDS in aqueous solution can be obtained, which is very advantageous for application in biosensing compared to nano-C60. FOQDs can effectively quench the fluorescence of dyes with different emission wavelengths that are tagged to bioprobes to an extent of more than 87% in aqueous buffer solution through a PET mechanism. Moreover, the nonspecific quenching of the fluorescent dyes (not bound to bioprobes) caused by FOQDs is negligible, so the background signal is extremely low which is beneficial for improving the detection sensitivity. Based on the π-π stacking interaction between FOQDs and bioprobes, such as single-stranded (ss) DNA and aptamers, a nucleic acid assay with a detection of limit of 15 pM and a highly sensitive OTA assay with a detection limit of 5 pg mL-1 in grape juice samples are developed through the simple "mix and measure" protocol based on luminescence quenching-and-recovery. This is the first demonstration of constructing biosensors utilizing the luminescence quenching ability of FOQDs through a PET mechanism, and the pronounced assay performance implies the promising potential of FOQDs in biosensing.

Electrochemical enantioselective sensor for effective recognition of tryptophan isomers based on chiral polyaniline twisted nanoribbon

Effective enantioselective recognition with chiral nanomaterials remains a challenge in the field of chemistry and biology. In this paper, a pair of left- and right-handed polyaniline (defined as S-PANI and R-PANI) were synthesized by chemical oxidation of aniline to form a specially twisted nanoribbon, which was induced by enantiomeric camphorsulfonic acid. Both S-PANI and R-PANI were used to construct electrochemical chiral sensors for the discrimination of tryptophan isomers (D- and L-Trp). Owing to the formation of efficient chiral nanospace with special nanoribbon morphology and enormous amounts of oxygen-containing functional groups of S-PANI or R-PANI, the high enantioselectivity was obtained with the recognition efficiency of 4.90 (D-Trp) on S-PANI and 4.20 (L-Trp) on R-PANI, respectively. The obtained chiral electrodes were also used for the determination of the enantiomeric excess (ee) for Trp, and a good linear relationship between peak currents and ee% of Trp was obtained. Furthermore, the strategy we proposed has tremendous potential in enantiomer recognition field.

Molecular insights on the dynamic stability of peptide nucleic acid functionalized carbon and boron nitride nanotubes

The strategic approaches to the design of self-assembled hybrids of biomolecular systems at the nanoscale such as deoxyribonucleic acid (DNA) with single-wall carbon nanotubes (CNTs) and their structural analog, boron nitride nanotubes (BNNTs), rely on understanding how biomolecules recognize and mediate intermolecular interactions with the nanomaterial's surface. In this paper, we consider peptide nucleic acid (PNA), which is a synthetic analog of DNA, and investigate its interaction with a zigzag CNT and BNNT of similar diameter. The results based on the molecular dynamics method find that PNA provides definitive contrasts in the adsorption on the tubular surface in aqueous solution: it prefers to wrap along the circumferential direction on a (11,0) CNT, whereas it binds along the axial direction adopting an extended configuration on a (11,0) BNNT. Moreover, gas-phase Monte Carlo simulations show a dependence of the nanotube diameter on the calculated adsorption energy, with BNNTs exhibiting higher adsorption energy compared to CNTs, and the largest-diameter (25,0) tubular configuration facilitates encapsulation of PNA rather than PNA being adsorbed on its sidewall. The results are expected to be of relevance in the design of novel PNA-based archetypal hybrid materials for nanoscale applications in health-related areas including biosensing.

DNA-Driven Nanoparticle Assemblies for Biosensing and Bioimaging

DNA molecules with superior flexibility, affinity and programmability have garnered considerable attention for the controllable assembly of nanoparticles (NPs). By controlling the density, length and sequences of DNA on NPs, the configuration of NP assemblies can be rationally designed. The specific recognition of DNA enables changes to be made to the spatial structures of NP assemblies, resulting in differences in tailorable optical signals. Comprehensive information on the fabrication of DNA-driven NP assemblies would be beneficial for their application in biosensing and bioimaging. This review analyzes the progress of DNA-driven NP assemblies, and discusses the tunable configurations determined by the structural parameters of DNA skeletons. The collective optical properties, such as chirality, fluorescence and surface enhanced Raman resonance (SERS), etc., of DNA-driven NP assemblies are explored, and engineered tailorable optical properties of these spatial structures are achieved. We discuss the development of DNA-directed NP assemblies for the quantification of DNA, toxins, and heavy metal ions, and demonstrate their potential application in the biosensing and bioimaging of tumor markers, RNA, living metal ions and phototherapeutics. We hihghlight possible challenges in the development of DNA-driven NP assemblies, and further direct potential prospects in the practical applications of macroscopical materials and photonic devices.