Noncovalent Adsorption Research Articles

Hybridization-driven synchronous regeneration of biosensing interfaces for Listeria monocytogenes based on recognition of fullerol to single- and double-stranded DNA

A novel sensitive and reusable electrochemical biosensor for Listeria monocytegenes DNA has been constructed based on the recognition of water-soluble hydroxylated fullerene (fullerol) to single- and double-stranded DNA. First, the fullerol was electrodeposited on glassy carbon electrode (GCE), acting as a matrix for non-covalent adsorption of single-stranded probe DNA. Upon hybridization with the target DNA, the double helix structure was formed and desorbed from the electrode surface, driving synchronous regeneration of the biosensing interfaces. The biosensor showed a probe DNA loading density of 144 pmol∙cm−2 with the hybridization efficiency of 72.2%. The biosensor is applicable for the analysis of target DNA in actual milk samples with recoveries between 101.0% and 104.0%. This sensing platform provides a simple method for the construction of sensitive and reusable biosensor to monitor Listeria monocytogenes-related food pollution.

Interface‐Driven DNA/Metal–Organic Framework Hybrids for Biosensing and Biomedical Applications

AbstractMetal–organic frameworks (MOFs) have emerged as promising materials for biosensing and biomedical applications due to their exceptional structural properties and tunable functionalities. Integrating functional DNA with MOFs offers numerous advantages, including enhanced colloidal stability, target‐induced signal amplification, improved cellular uptake, and controlled drug release. This focused review aims to highlight key insights into the DNA–MOF interface to facilitate the design and application of these conjugates. A succinct summary of the interactions between DNA and MOFs, covering both noncovalent adsorption and covalent conjugation is provided. Moreover, recent advancements in utilizing DNA–MOF conjugates in biosensors, with a specific emphasis on fluorescent and electrochemical sensing are discussed. Additionally, applications in bioimaging, controlled drug delivery, and nucleic acid delivery are explored. Finally, the limitations of existing designs and provide insightful perspectives for the future development of DNA–MOFs, aiming to expedite their integration and impact in the realm of biomedical applications are addressed.

Non-covalent interactions and adsorption affinities of doxycycline and tetracycline with the (010) and (001) surfaces of hydroxyapatite. A DFT and experimental study

Understanding the antibiotic interaction processes with hydroxyapatite (HA) surface is crucial for designing effective antibiotic release systems for treating inflammatory processes in calcified tissues. In this study, we investigated the non-covalent interactions and adsorption sites of the antibiotics doxycycline (DOX) and tetracycline (TC) on the (001) and (010) HA surfaces using transmission electron microscopy. The needle-shaped HA nanoparticles exhibited PO4-rich (010-PO4) and PO4-deficient (010-OH) surfaces. Adsorption isotherms of nearly stoichiometric HA (Ca10(PO4)6(OH)2) demonstrated Langmuir–Freundlich kinetics, with DOX showing a greater affinity than TC for the HA surface. Density functional theory atomistic simulations with three configurations of DOX and TC interacting with the 001, 010-PO4, and 010-OH surfaces revealed van der Waals interactions and hydrogen bonds at the interface. However, DOX exhibited higher adsorption energy than TC. Both molecules preferred to interact with the 010-PO4 surface in their stable configurations. However, the π-cation interactions between the aromatic ring of DOX and the Ca atoms on the HA surface were not observed in TC. Our findings further our understanding of the non-covalent interactions and adsorption sites of cyclines on the HA surface, thus promoting the design of more effective antibiotic release systems.

Conductive imprinted polymeric interfacially modified electrochemical sensors based on covalently bonded layer-by-layer assembly of Gr/Au with flower-like morphology for sensitive detection of 2,4,6-TCP.

Polymeric membrane sensors based on molecular imprinted polymers (MIPs) have been attractive analytical tools for detecting organic species. However, the MIPs in electrochemical sensors developed so far are usually prepared by in situ polymerization of pre-polymers and non-covalent adsorption on the surface of the working electrode. Meanwhile, the MIPs in the electrochemical sensors developed are typically made of a non-conductive polymer film. This results in a relatively low current due to the lack of electron transfer. Additionally, the smoothness of the traditional electrochemical substrate results in a low specific surface area, which reduces the sensitivity of the electrochemical sensor. Here, we describe a novel electrochemical sensor with a conductive interface and MIPs modification. The electrochemical sensor was modified by covalent coupled layer by layer self-assembly with the imprinted polymer film. The incorporation of these two conductive functional materials improves the conductivity of the electrodes and provides interface support materials to obtain high specific surface area. By using 2,4,6-trichlorophenol as the model, the sensitivity of the developed conductive sensor was greatly improved compared to that of the traditional MIPs sensor. We believe that the proposed MIPs-based sensing strategy provides a general and convenient method for making sensitive and selective electrochemical sensors.

Non-covalent adsorption of neurotransmission-relevant proteins on locally laser-oxidized and pristine graphene

Femtosecond pulsed laser two-photon oxidation (2PO) was used to modulate protein adsorption on graphene surfaces on a Si/SiO2 substrate. The adsorption behavior of calmodulin (CaM) and a muscarinic acetylcholine receptor...

Mass transfer study on noncovalent adsorption and desorption of soluble phenolics by plant cell wall materials for green purification

This study originated from the observation that plant cell walls can bind soluble phenolics through noncovalent interactions. Celery and blueberry cell wall materials obtained from waste sources were selected as effective adsorbents for purifying phenolics. First, the impact of environmental ionic strength on the adsorption of phenolics by plant cell walls was investigated, indicating that ionic interactions play a more important role in adsorption than hydrophobic interactions. Second, numerical simulation results found that the increments of diffusivities of phenolics both within the liquids in the pores of plant cell wall materials and the skeleton of cell wall adsorbents accelerated the adsorption. The abundance of adsorption sites within plant cell wall adsorbents determined their adsorption capacity, and the penetration of phenolics across the adsorbent/liquid interface was unrelated to the adsorption behavior. Third, due to the porous structure of celery cell wall adsorbents, the pore volume diffusion of phenolics impacted intraparticle diffusion within celery cell wall materials more than blueberry cell wall materials. Fourth, after plant cell wall adsorption and desorption, the obtained phenolics achieved a purity of 60%, comparable to the purification achieved by macroporous resin adsorption/desorption. Moreover, purification using plant cell wall adsorption/desorption was more efficient. These findings contribute to the theoretical understanding of interactions between plant cell walls and polyphenols and provide valuable insights for designing natural plant cell wall adsorbents and developing environmentally friendly polyphenol purification techniques.

Characterizing the Non-Covalent Binding of a Pyrene-Derived Linker for DNA Immobilization on Graphene Field-Effect Transistors

Graphene field-effect transistors (G-FETs) constitute an emerging platform for biosensing applications. Most genomic applications with G-FETs use single-stranded DNA (ssDNA) as probes in order to capture a specific target DNA sequence and to detect the corresponding change in the electrical response of the sensor1. Controlling the distribution of DNA probes on the graphene surface is crucial to the sensitivity, selectivity and reproducibility of the sensors1. The most popular immobilization approach uses a non-covalent linker molecule named 1-pyrenebutanoic acid succinimidyl ester (PBASE)1. This bifunctional molecule binds to the graphene surface through non-covalent π-π interactions via its aromatic pyrene group, and on the other end, its succinimidyl ester group can form a covalent bond with amine groups added to the terminal end of ssDNA probes. However, the adsorption process of PBASE molecules is not well controlled, which represents a limitation in the optimization of G-FET biosensors.Here, we present an investigation of the kinetics of the non-covalent adsorption of PBASE on graphene, in order to control the density of ssDNA probes for biosensing applications with G-FETs. We fabricated G-FET sensor arrays using CVD-grown graphene and photolithography techniques, as described previously2. First, we investigated the effect of incubation time on PBASE coverage on graphene, using electrical curves as well as Raman hyperspectral imaging (RIMA). We report a significative and reproducible electrical signature for the PBASE compared to the control without PBASE. We find that this electrical signature appears and saturates quickly compared to the timescales usually reported in the literature. Corroborating results were obtained with RIMA spectroscopy, showing a rapid response of the graphene modes following PBASE incubation. Next, we studied the effect of PBASE accumulation on the assembly of ssDNA probes. We will discuss the combined effect of PBASE accumulation and screening effects in saline buffer on the electrical signature of ssDNA probes. Our results will enable a better control on the non-covalent functionalization of graphene with PBASE for the assembly of various biomolecular probes for biosensing applications.1. Béraud A, Sauvage M, Bazan CM, Tie M, Bencherif A, Bouilly D. Graphene field-effect transistors as bioanalytical sensors: design, operation and performance. Analyst. 2021;(146):403-428.2.Bazan CM, Béraud A, Nguyen M, Bencherif A, Martel R and Bouilly D. Dynamic Gate controlled of Aryldiazonium chemistry on Graphene field-effect transistors. Nano Lett. 2022;22(7):2635-2642.

PEGylated bottom-up synthesized graphene nanoribbons loaded with camptothecin as potential drug carriers

This work discusses the potential use of bottom-up synthesized graphene nanoribbons (GNRs) as nano-carriers for drug delivery systems (DDSs). GNRs have a high loading capacity for anticancer drugs due to their high specific surface area and non-covalent adsorption with hydrophobic anticancer drug molecules. Herein, we synthesized GNRs using a bottom-up approach, modified with PEG2000 (GNR-PEG) and PEG2000 carrying folic acid chains (GNR-PEG-FA), and then loaded with camptothecin (CPT). The targeting ability mediated by folic acid of the GNR derivative was evaluated using cellular assays, and the cytotoxicity of GNR systems loaded with CPT was assessed by in vitro studies. They suggest that the functionalization of GNR derivatives with folic acid significantly affects their interaction with cells expressing different levels of folic acid receptors. The authors also explore the possibility to employ GNRs in photothermal therapy (PTT). GNR-PEG and GNR-PEG-FA display minor or no toxicity in standard cell cultures, but they show remarkable thermal response upon NIR irradiation, causing complete loss of cell viability within a few hours of treatment. This work highlights the potential of GNRs as DDSs and emphasizes the importance of further research on their biocompatibility and as a platform for PTT.

Aptamer tuned nanozyme activity of nickel-metal–organic framework for sensitive electrochemical aptasensing of tetracycline residue

It is urgently needed to develop high-performance method for tetracycline (TC) analysis to meet the growing concerns about food safety. Herein, a MOF of Ni2+-2,3,6,7,10,11-hexahydroxytriphenylene (Ni-HHTP) with peroxidase activity has been prepared and coated on a screen printing electrode, followed by non-covalent adsorption of tetracycline aptamer (TC-Apt) through the π-stacking. The spectroscopic and electrochemical assays show that TC-Apt can effectively enhance the nanozyme activity of Ni-HHTP using 3,3′,5,5′-tetramethylbenzidine (TMB)/H2O2 as the probe. Upon binding with TC, the configuration of TC-Apt is changed and desorbs from the Ni-HHTP, resulting in the decrease of the nanozyme activity of aptasensor. Based on this principle, the target TC can be analyzed in concentrations ranging from 10 pM to 1.0 μM, with a detection limit of 1.9 pM. The aptsensor is also applicable for TC analysis in fresh Ctenopharyngodon idella meat and milk, which provides a new approach for TC residue monitoring in food.

Interaction of G-quadruplex Forming DNA Aptamers with PAMAM Dendrimers Studied by Dynamic Light Scattering and UV-VIS Spectrophotometry.

The complexes of G-quadruplex forming DNA thrombin binding aptamers (TBA) and polyamidoamine dendrimers (PAMAM) were studied with the aim to form a model targeted drug delivery system. Hydrodynamic diameter, zeta potential and melting temperature (Tm ) were investigated by dynamic light scattering and UV-VIS spectrophotometry. Non-covalent adsorption by means of electrostatic interaction between positively charged amino groups of dendrimers (+) and negatively charged phosphate groups of aptamers (-) has driven the formation of aggregates. The size of complexes was in the range of 0.2-2 μm and depended on the type of dispersant, charge ratio (+/-) and temperature. Raising the temperature increased the polydispersity, new smaller size distributions were observed indicating the G-quadruplex unfolding. The melting transition temperature of TBA aptamer was affected by the presence of amino-terminated PAMAM rather than carboxylated succinic acid PAMAM-SAH dendrimer, thus supporting the electrostatic nature of interaction that disturbed denaturation of target-specific quadruplex aptamer structure.

Noncovalent Adsorption of Single-Stranded and Double-Stranded DNA on the Surface of Gold Nanoparticles

Understanding the patterns of noncovalent adsorption of double-stranded nucleic acids (dsDNA) on gold nanoparticles (GNPs) was the aim of this study. It was found that the high-affinity motifs in DNA can and do act as an “anchor” for the fixation of the whole molecule on the GNP (up to 98 ± 2 single-stranded (ss)DNA molecules per particle with diameter of 13 ± 2 nm). At the same time, the involvement of an “anchor” in the intramolecular DNA interaction can negatively affect the efficiency of the formation of ss(ds)DNA–GNP structures. It has been shown that the interaction of GNP with DNA duplexes is accompanied by their dissociation and competitive adsorption of ssDNAs on GNP, wherein the crucial factor of DNA adsorption efficiency is the intrinsic affinity of ssDNA to GNP. We propose a detailed scheme for the interaction of dsDNA with GNPs, which should be taken into account in studies of this type. Researchers focused on this field should accept the complicated nature of such objects and take into account the many competing processes, including the processes of adsorption and desorption of DNA on gold as well as the formation of secondary structures by individual DNA strands.

Whether carbon nanotubes are suitable for delivering small drugs with aromatic rings through non-covalent adsorption?

Carbon Nanotubes (CNTs) have shown great prospect in the field of biomedicine. CNTs often act as vehicles to carry drugs through covalent attachment or noncovalent adsorption, due to their large surface area. Their hollow channels can also accommodate small drugs. However, the drugs may be trapped because of the great potential well of drugs in CNT, which is unfavorable to drug release. Whether CNTs are suitable for delivering small drugs especially those with aromatic rings is still unclear. In this work, we performed molecular dynamics simulations to study the transmembrane transport of drug carried by CNTs. Primidone (abbreviated as PRI) was selected as a model small drug, which has two aromatic rings that can interact with CNTs through π-π stacking. Two patterns of drug loading were taken into consideration. One is that drugs are trapped in the CNTs and another is that drugs are adsorbed on outer CNT surface. The two formed CNT-PRI complexes are thermodynamically stable in the water. Potential of mean force calculations show that CNTs have a great potential well to trap PRI molecules, which is not beneficial for PRI release from CNTs into the membrane. When PRI adsorbed on CNT surface, the complex can readily permeate into the membrane. Only after entering the lipid bilayer, can PRI leave the CNT and then diffuse in the membrane. Our results demonstrate that CNT’s inner space is not suitable to carry small drugs with aromatic rings, as π-π stacking enhances the trap of drugs in CNT and drugs are hard to leave. However, using CNT outer space to carry and deliver small drugs with aromatic rings is theoretically feasible. These findings may provide new insights for the drug delivery using CNTs as vehicles.

Coating peanut shell lignin nanospheres with gelatin via non-covalent adsorption: Key parameters, consequences, and underlying interactions

In the present work, lignin nanospheres (LNS, average diameter 166.43 nm) were prepared and the affecting parameters, the absorbed types, and mechanisms of their interactions with type-A gelatin (AG) were explored. The findings demonstrated that upon AG coating, the ζ-potential of LNS sharply decreased and concluded a negative-to-positive shift, while the average diameter and polydispersity index increased significantly. AG presented the highest coating capacity (0.32 mg/mg, db) onto LNS (0.5 mg/mL) at an optimum pH of 4.0 and an AG concentration of 1.0 mg/mL. The adsorption of AG onto LNS could be well described by the Hill model (R2 = 0.9895), which was characterized as positive synergistic adsorption by the Hill coefficient (1.32) and physical adsorption by the free energy (3.70 kJ/mg). The spectral analysis revealed that the interactions between AG and LNS were mainly driven by electrostatic forces (ΔG < 0, ΔH < 0, and ΔS > 0) together with the assistance of hydrogen bonds and hydrophobic interactions, which companied a decrease of α-helix (4.04 %) and β-turn (0.60 %) and an increase of β-sheet (3.10 %) and random coil (1.53 %) of the secondary structure of AG. The results herein certainly favored the hydrophilic/hydrophobic change of LNS/AG and the quality control of a binary system consisting of lignin and gelatin.

Non-covalent interaction, adsorption characteristics and solvent effect of procainamide anti-arrhythmias drug on silver and gold loaded silica surfaces: SERS spectroscopy, density functional theory and molecular docking investigations.

First-principle calculations were systematically carried out to explore the structural and electronic properties of the non-covalent interaction of procainamide (PA) anti-arrhythmias drug molecules on silver-loaded and gold-loaded silica nanostructures. Computed adsorption energies presented a higher affinity of PA towards the Ag-SiO2 as compared with Au-SiO2 surfaces. The non-covalent interaction analysis revealed a weak van der Waals type of forces and hydrogen bonding, associated with a noticeable repulsive steric interaction. It was conceived that silver and gold decorated silica can be used for drug administration in biological systems due to the fact that their frontier molecular orbital energy levels were considerably altered upon absorption, decreasing the pertinent energy gaps. Moreover, the electronic spectra of PA⋯Ag-SiO2 and PA⋯Au-SiO2 structures investigated in different solvents display a notable blue shift, suggesting that noble metal-loaded silica can be effective in the context of drug delivery systems. Therefore, silver- and gold-decorated silica of three possible drug adsorption scenarios was fully analyzed to realize the associated bioactivity and drug likeness. Theoretical findings suggest that Ag- and Au-SiO2 nanocomposites can be considered potential drug delivery platforms for procainamide in medication protocols.

Adsorption energies on transition metal surfaces: towards an accurate and balanced description

Density functional theory predictions of binding energies and reaction barriers provide invaluable data for analyzing chemical transformations in heterogeneous catalysis. For high accuracy, effects of band structure and coverage, as well as the local bond strength in both covalent and non-covalent interactions, must be reliably described and much focus has been put on improving functionals to this end. Here, we show that a correction from higher-level calculations on small metal clusters can be applied to improve periodic band structure adsorption energies and barriers. We benchmark against 38 reliable experimental covalent and non-covalent adsorption energies and five activation barriers with mean absolute errors of 2.2 kcal mol−1, 2.7 kcal mol−1, and 1.1 kcal mol−1, respectively, which are lower than for functionals widely used and tested for surface science evaluations, such as BEEF-vdW and RPBE.

Mechanical Stability of DNA Corona Phase on Gold Nanospheres.

Noncovalent adsorption of biopolymers on the surface of gold nanoparticles (AuNPs) forms a corona phase that drastically diversify AuNP functions. However, mechanical stabilities of such corona phase are still obscure, hindering the application of biopolymer-coated AuNPs. Here, using optical tweezers, we have observed, for the first time, that DNA corona phase adsorbed on a 5 nm AuNP via two (dA)21 strands in proximity can withstand an average desorption force of 40 pN, which is higher than the stall force of DNA/RNA polymerases. This suggests a new role for AuNPs to modulate replications or transcriptions after binding to prevalent poly(dA) segments in eukaryotic genomes. We have also revealed that with increasing AuNP size (1.8-10 nm), DNA corona becomes harder to remove, likely due to the larger surfaces and flatter facets on bigger AuNPs. These findings provide guidance to design AuNP corona that can withstand harsh environments for biological and materials applications.

Biomimetic Adsorptive Composites for Redox Remediation of Organic Pollutants

Conductive hydrogels have gained interest as responsive materials for pollutant sensing and degradation in a variety of applications such as wastewater and soil remediation. There has been a significant increase in both commercial and domestic wastewater, which is output into ground sources, acting as a leading contaminant for surrounding communities. Specifically, cationic organic textile dyes such as methylene blue, methyl red, and methyl violet which are known monoamine oxidase inhibitors are prevalent pollutants. To improve remediation, this work employs a biopolymeric (i.e. polysaccharide) matrix to aid in non-covalent adsorption of pollutants to the network. Additionally, modification of the polysaccharide backbone with a conductive polymer can promote electron transfer throughout the matrix. This work employs the photoinitiation of a metal-polysaccharide complex to directly polymerize polyaniline (PANI) on the polysaccharide backbone. The PANI-functionalized composite can be utilized as a reducing substrate for the adsorptive redox remediation of the organic pollutants that occur in contaminated soils or water supplies.

Flexible Hybrid Electronics Nanofiber Electrodes with Excellent Stretchability and Highly Stable Electrical Conductivity for Smart Clothing.

In this paper, a side-by-side, dual-nozzle electrospinning process was used to prepare a flexible hybrid electronics (FHE) material with excellent stretchable properties. A highly stable electrical conductivity was also imparted to the resulting membrane electrodes using silver nanoparticles (AgNPs) and carbon-based nanomaterials of different structures. The AgNP/carbon-based nanomaterials were coated onto bicomponent polymer nanofibers (composed of polyurethane (PU) and polyvinylidene difluoride (PVDF)) on the nanofiber membrane. The FHE nanofiber electrodes were finally integrated into clothing designed to accurately measure human body sensing signals (e.g., electrocardiography (ECG) and electromyography (EMG) signals). To effectively increase the high electrical conductivity, a polymer-type dispersant (polyisobutylene-b-poly(oxyethylene)-b-polyisobutylene, a triblock copolymer) was used to effectively and stably disperse AgNPs with different particle sizes and carbon-based nanomaterials with different geometric dimensions (e.g., zero-dimensional carbon black, one-dimensional carbon nanotubes, and two-dimensional graphene) through non-covalent adsorption. Moreover, the bicomponent PVDF-PU nanofibers were immersed in a mixed dispersant of AgNPs and carbon-based nanomaterials at low concentrations, and thermal post-treatment was conducted to improve the electrical conductivity. The AgNP/graphene oxide (GO) nanofiber electrode exhibited a continuous phase with a stable material microstructure after 5000 repetitions of 50% tension-tension fatigue testing. The waveform pattern obtained from the proposed AgNP/GO nanofiber electrode was compared with those of traditional ECG and EMG electrodes. The nanofiber web electrode treated with organic/inorganic mixed dispersants and verified via tests of its electrical and fatigue properties was found to be suitable for long-term ECG and EMG monitoring, and it has excellent potential in wearable smart sensors.

Modularity of RBC hitchhiking with polymeric nanoparticles: testing the limits of non-covalent adsorption

Red blood cell (RBC) hitchhiking has great potential in enhancing drug therapy, by improving targeting and reducing rapid clearance of nanoparticles (NPs). However, to improve the potential for clinical translation of RBC hitchhiking, a more thorough understanding of the RBC-NP interface is needed. Here, we evaluate the effects of NP surface parameters on the success and biocompatibility of NP adsorption to extracted RBCs from various species. Major differences in RBC characteristics between rabbit, mouse and human were proven to significantly impact NP adsorption outcomes. Additionally, the effects of NP design parameters, including NP hydrophobicity, zeta potential, surfactant concentration and drug encapsulation, on RBC hitchhiking are investigated. Our studies demonstrate the importance of electrostatic interactions in balancing NP adsorption success and biocompatibility. We further investigated the effect of varying the anti-coagulant used for blood storage. The results presented here offer new insights into the parameters that impact NP adsorption on RBCs that will assist researchers in experimental design choices for using RBC hitchhiking as drug delivery strategy.

Covalent Attachment and Detachment by Reactive DESI of Sequence-Coded Polymer Taggants.

The use of sequence-defined polymers is an interesting emerging solution for materials identification and traceability. Indeed, a very large amount of identification sequences can be created using a limited alphabet of coded monomers. However, in all reported studies, sequence-defined taggants are usually included in a host material by noncovalent adsorption or entrapment, which may lead to leakage, aggregation, or degradation. To avoid these problems, sequence-defined polymers are covalently attached in the present work to the mesh of model materials, namely acrylamide hydrogels. To do so, sequence-coded polyurethanes containing a disulfide linker and a terminal methacrylamide moiety are synthesized by stepwise solid-phase synthesis. These methacrylamide macromonomers are afterward copolymerized with acrylamide and bisacrylamide in order to achieve cross-linked hydrogels containing covalently-bound polyurethane taggants. It is shown herein that these taggants can be selectively detached from the hydrogel mesh by reactive desorption electrospray ionization. Using dithiothreitol the disulfide linker that links the taggant to the gel can be selectively cleaved. Ultimately, the released taggants can be decoded by tandem mass spectrometry.