Adsorption Of Biomolecules Research Articles

Loach mucus-like guanosine-based hydrogel as an antifouling coating for electrochemical detection of tau protein

Alzheimer's disease (AD) is the most common neurodegenerative disease that causes dementia in the elderly. Total tau in the blood is a potentially useful biomarker for predicting early AD. However, during detection, the non-specific adsorption of high-abundance biomolecules in the sample will block the detection signal and reduce the detection sensitivity. Based on this, this work described an electrochemical biosensor with high antifouling performance based on loach mucus-inspired guanosine-based hydrogel for the specific detection of tau protein. The exploited electrochemical biosensor shows high sensitivity and selectivity for tau protein detection, with a wide linear response range from 1.00 × 10−2 to 1.00 × 102 ng/mL and a low limit of detection (LOD) of 1.31 × 10−3 ng/mL. This LOD is lower than the critical tau protein concentration (0.2 ng/mL) that distinguishes AD cases, indicating that this simple tau protein immunoassay has the potential for clinical application. Furthermore, due to the facile fabrication, good biocompatibility, facile biofunctionalization, and antifouling property of this hydrogel film, hydrogel-based biosensors also have the potential to detect other biomarkers in complex biological samples.

Combining Topography and Chemistry to Produce Antibiofouling Surfaces: A Review.

Despite decades of research on the reduction of surface fouling from biomolecules or micro-organisms, the ultimate antibiofouling surface remains undiscovered. The recent covid-19 pandemic strengthened the crucial need for such treatments. Among the numerous approaches that are able to provide surfaces with antibiofouling properties, chemical, biological, and topographical strategies have been implemented for instance in the marine, medical, or food industries. However, many of these methods have a biocidal effect and, with antibioresistance and biocide resistance a growing threat on humanity, strategies based on reducing adsorption of biomolecules and micro-organism are necessary for long-term solutions. Bioinspired strategies, combining both surface chemistry and topography, are currently at the heart of the best innovative and sustainable solutions. The synergistic effect of micro/nanostructuration, together with engineered chemical or biological functionalization is believed to contribute to the development of antibiofouling surfaces. This review aims to present approaches combining hydrophobic or hydrophilic chemistries with a specific topography to avoid biofouling in various industrial environments and healthcare facilities.

Biomolecules adsorption to trigger the self-assembly of nanospheres and nanorods

HypothesisThe self-assembly (SA) of nanostructures triggered by the adsorption of biomolecules (BSA) is investigated as a platform to develop diagnostics and functional applications. Mixing nanostructures of different morphologies; SiO2 nanospheres (NS) to a cellulose nanorod crystals (CNC) leads to the formation of short range ordered domains in the dried film. Adding biomolecules-treated SiO2 NS into the CNC develop the long range ordered assembly in the composite film. ExperimentsThe CNC-SiO2 composite films were prepared by mixing CNC suspension (3 wt%) with the SiO2 NS of different concentration (0.5–5 mg/mL) followed by drying at the ambient conditions. The CNC-SiO2 @BSA films are prepared by first mixing the BSA (1 mg/mL) with the SiO2 suspension of different concentrations. Later the SiO2 @BSA suspension was mixed with the CNC and left for drying at the ambient conditions. The self-assembly mechanisms of CNC, SiO2 and BSA are studied by combining SEM, DLS, UV-Vis, QCM-D and SAXS analysis. FindingsThe SA mechanism of aqueous suspensions of CNC blended with SiO2 NS pre-treated with BSA (by adsorption) is studied by a combination of small angle X-ray scattering (SAXS), scanning electron microscopy (SEM), UV-Vis spectroscopy (UV-Vis), dynamic light scattering (DLS) and quartz crystal microbalance with dissipation (QCM-D). Both CNC and SiO2 NS are negatively charged and have demonstrated self-assembly ability driven from a combination of long- and short- range order arrangement. Adding SiO2 NS to a CNC suspension disrupts the original SA of both CNC and SiO2, which leads to the formation of small, short- range ordered domains of large polydispersity. Surprisingly, adding BSA-treated SiO2 NS into the CNC network enhances the arrangement of CNC and NS towards a new system with long range ordered assembly. The SA mechanisms of cellulose-SiO2 composites result from the balance of electrostatic repulsion and van der Waal attraction in the structure factor, radial distance distribution and potential of mean force. Understanding the effect of biomolecule adsorption on the self-assembling mechanisms of CNC nanorods with SiO2 nanospheres enables the efficient engineering of catalysis, biosensors and diagnostics.

Cell Membrane and V2C MXene-Based Electrochemical Immunosensor with Enhanced Antifouling Capability for Detection of CD44.

The inactive adsorption and interference of biomolecules in electrochemical biosensors is a topic of intense interest. Directly utilizing native cell membranes to endow electrochemical surfaces with antifouling and biocompatible features is a promising strategy, rather than attempting to synthetically replicate complex biological interface properties. In this study, we present a facial and sensitive sandwich-type antifouling immunoassay through platelet membrane/Au nanoparticle/delaminated V2C nanosheet (PM/AuNPs/d-V2C)-modified electrode as the substrate of sensing interface and methylene blue/aminated metal organic framework (MB@NH2-Fe-MOF-Zn) as an electrochemical signal probe. The biosensor perfectly integrates the high conductivity of AuNPs-loaded V2C MXene with the excellent loading property of NH2-Fe-MOF-Zn to improve the electrochemical sensing performance. In addition, the excellent antifouling properties of the homogeneous cell membrane can effectively prevent the non-specific adsorption of model proteins. The obtained antifouling biosensor possesses the capability of ultrasensitive detection of CD44 and CD44-positive cancer cell in complex liquids and exhibits good analytical performance for the analysis of CD44 with a linear range from 0.5 ng/mL to 500 ng/mL. This strategy of developing cell membrane-based biosensing systems with enhanced antifouling capability can be easily expanded to the construction of other complex biosensors, and the advanced biological probes and analytical methods provide a favorable means to accurately quantify biomarkers associated with tumor progression.

Contamination and carryover free handling of complex fluids using lubricant-infused pipette tips

Cross-contamination of biological samples during handling and preparation, is a major issue in laboratory setups, leading to false-positives or false-negatives. Sample carryover residue in pipette tips contributes greatly to this issue. Most pipette tips on the market are manufactured with hydrophobic polymers that are able to repel high surface tension liquids, yet they lack in performance when low surface tension liquids and viscous fluids are involved. Moreover, hydrophobicity of pipette tips can result in hydrophobic adsorption of biomolecules, causing inaccuracies and loss in precision during pipetting. Here we propose the use of lubricant-infused surface (LIS) technology to achieve omniphobic properties in pipette tips. Using a versatile and simple design, the inner lumen of commercially available pipette tips was coated with a fluorosilane (FS) layer using chemical vapor deposition (CVD). The presence of FS groups on the tips is confirmed by x-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) tests. After lubrication of the tips through a fluorinated lubricant, the omniphobicity and repellent behaviour of the tips drastically enhanced which are revealed via static and hysteresis contact angle measurements. The repellency of the lubricant-infused pipette tips against physical adsorption is investigated through pipetting a food coloring dye as well as human blood samples and are compared to the untreated tips. The results show significantly less amount carryover residue when the lubricant-infused tips are utilized compared to commercially available ones. We also demonstrate the lubricant-infused tips reduce bacteria contamination of the inner lumen by 3 to 6-log (over 99%, depending on the tip size) after pipetting up and down the bacteria solution.

Design of a high-performance graphene/SiO2-Ag periodic grating/MoS2 surface plasmon resonance sensor.

This study optimizes a surface plasmon resonance (SPR) sensor based on SiO2-Ag periodic grating using graphene and a MoS2 hybrid structure to enhance sensitivity. The sensing performance was analyzed by wavelength modulation. By optimizing the structural parameters, we can obtain the quality factor and sensitivity of 90.192RIU-1 and 960nm⋅RIU-1. The periodic grating surface covered with MoS2 prevents the oxidation of the silver layer and increases the adsorption of biomolecules. Compared with the conventional silver grating SPR sensor, the sensor's sensitivity and quality factor can be significantly enhanced. Experiments were carried out using sucrose solutions with different refractive indices, and the results indicate there was a good linear relationship between the resonance wavelength and the sucrose solution. The sensor has vast potential for practical applications.

Effect of tribologically-induced changes in surface termination of silicon-containing diamond-like carbon coatings on the resistance to biomolecule adsorption

Silicon-containing diamond-like carbon (DLC) is a class of thin-film materials with excellent mechanical properties, high thermal stability, and good tribological performance over a wide range of environmental conditions. While non-alloyed/non-doped DLCs also exhibit good biocompatibility and bioinertness, our understanding of the effect of silicon in DLCs on biomolecules/DLC interactions is still elusive. Here, we evaluated the structural, mechanical, and tribological properties of Si-containing DLC coatings with silicon content fraction of 11% and 16%. Tribological tests, performed by sliding a stainless steel pin on the coatings in water, indicated a low friction response (steady-state coefficient of friction <0.11), while quartz crystal microbalance experiments indicated no adsorption of a model biomolecule, namely adenosine triphosphate (ATP), on Si-containing DLCs. Near-edge X-ray absorption fine structure spectromicroscopy analyses performed after tribological experiments provided evidence for an increase in the fraction of silanol surface terminal groups formed in the worn region upon sliding in water without any significant sp3-to-sp2 rehybridization of carbon atoms. The fraction of surface hydroxyl groups in the worn region increases with the silicon content in Si-containing DLC, which leads to a decrease in friction. This tribologically-induced change in surface termination did not lead to the adsorption of ATP upon incubation of tribotested samples in ATP solutions for several hours. These findings open the path for the use of Si-containing DLC in applications requiring good tribological properties in aqueous solution and an excellent resistance to biomolecule surface adsorption that is maintained even after tribologically-induced variations in surface termination.

Optical Detection of Fat Concentration in Milk Using MXene-Based Surface Plasmon Resonance Structure.

MXene (Ti3C2Tx) has emerged very recently as an interacting material for surface plasmon resonance (SPR) configuration. It was discovered that Ti3C2Tx can facilitate the adsorption of biomolecules due to its higher binding energies, stronger interaction between matter and light, and larger surface area. In this work, a two-dimensional Ti3C2Tx and silicon layer-based SPR refractometric sensor is proposed for the sensitive and fast detection of milk fat concentration due to the high significance of this issue to people all over the world. The proposed SPR structure employs BK7 (BK7 is a designation for the most common Borosilicate Crown glass used for a variety of applications in the visible range) as a coupling prism and silver as a metal layer. The layer thicknesses and the number of Ti3C2Tx sheets are optimized for the highest performance. The highest reached sensitivity is 350 deg./RIU with 50 nm silver and 4 nm silicon with a monolayer of Ti3C2Tx, which is ultra-high sensitivity compared to the latest work that utilizes SPR configuration. The proposed SPR-based sensor’s ultra-high sensitivity makes it more attractive for usage in a variety of biosensing applications.

Effect of Molecular Weights on Metal-Mediated Grafting of Sulfobetaine Polymers onto Solid Surfaces for Non-Biofouling Applications.

The grafting of zwitterionic molecules onto solid surfaces is an important tool for decreasing the unwanted adsorption of biomolecules, such as proteins, bacteria, and cells. This has been achieved through various approaches, such as zwitterionic monolayer/multilayer formation, surface-initiated polymerization of zwitterionic monomers, and grafting of presynthesized zwitterionic polymers. Recently, a coordination-driven approach to grafting zwitterionic polymers onto solid surfaces has been discovered to be an effective method because of its versatility and robustness. However, the bacterial adhesion resistance of zwitterionic polymer grafting has been explored using only one molecular weight, and the non-biofouling performance against other fouling organisms has remained unexamined. In this study, the characteristics of coordination-driven surface zwitteration are systematically investigated. Sulfobetaine (SB) polymers with three different molecular weights are synthesized and employed for surface grafting. Polydopamine is used as a surface primer, and SB polymers are grafted onto the surfaces via the formation of metal-mediated coordinate bonds. The effect of molecular weight on the grafting efficiency and non-biofouling performance is investigated via protein adsorption and marine diatom adhesion assays. The SB polymer with a high molecular weight is found to be crucial for achieving strong resistance to protein adsorption and marine fouling.

Research on Tunable SPR Sensors Based on WS2 and Graphene Hybrid Nanosheets

A prismatic excitation-based affinity biosensor consisting of the prism (BK7), WS2/graphene hybrid nanosheets, and silver (Ag) as the active metal for the surface plasmon resonance is proposed in this present research. The introduction of the transition metal WS2/graphene layer protected the silver substrate and enhanced the adsorption of biomolecules, which facilitated the quality and performance of detection. Here, we improved the detection structure by focusing on the metallic materials, graphene and WS2 film layers, and the thickness of the measured medium on the sensing effect. The results show that the silver film had a more desirable resonance effect, and the design of the symmetric detection structure produced a double resonance peak, and it provides a reference for distributed sensing. Changing the thickness of the detection medium can dynamically adjust the wave vector matching conditions, which gives the sensor a certain tunability. In the bilayer WS2 and monolayer graphene (W = 2, G = 1) configuration, the sensitivity was up to 224 deg/RIU with a quality factor of 96.97 RIU−1, which has potential for clinical analytic and biochemical detecting applications.

Adsorption and Mechanism of Glycine on the Anatase with Exposed (001) and (101) Facets

As a widely existing mineral types on Earth, semiconductor minerals play an important role in the origin of life and the material geochemical cycle. The first step of peptide formation is amino acid adsorption on the mineral surface, but the role and mechanism of different crystal facets of semiconductor minerals are not well understood. Anatase (TiO2) with exposed (001) facets was synthesized by a hydrothermal method, and then analyzed and compared with the purchased ordinary anatase (TiO2) for the adsorption of glycine, the simplest amino acid. XRD, SEM and TEM results show that the hydrothermally synthesized anatase (TiO2) has a good anatase crystal form, which is micro-nano-scale flake particles and mainly composed of (001) facets. The results of HPLC used in the adsorption experiment showed that under optimal conditions (pH 5 to 6, an adsorption time of 24 h, and an initial concentration of 0.09 mol/L), the adsorption quantity of glycine on anatase (TiO2) with exposed (001) facets may reach 10 mg/m2, which is larger than that for ordinary anatase (TiO2) with exposed (101) facets. Based on a combination of various characterizations and simulation calculations, the results proved that anatase can activate thermodynamically stable γ-glycine to β-glycine. The adsorption of glycine on anatase (TiO2) has two forms, one is the zwitterionic form in which the carboxyl group forms a bridge structure with two Ti atoms connected by surface bridging oxygen, and the dissociated form is in which the amino group forms a bond with the surface Ti atom. Among these, glycine is mainly adsorbed to anatase by dissociative molecules on the anatase (TiO2) with exposed (001) facets and by zwitterion adsorption on the anatase (TiO2) with exposed (101) facets. This research elucidates the conditions and mechanism of amino acid adsorption by semiconductor minerals in weak acidic environment, which is similar to the environmental pH that was beneficial to the formation of life on the early Earth. Therefore, these can provide a reference for the further study of the role of semiconductor minerals in the adsorption and polymerization of small biomolecules in the origin of life.

Comparative study of green synthesised sulphur nanoparticles in different acidic media

Sulphur nanoparticles (SNPs) are of great importance, due to their tremendous use in agriculture and industries. In the present work, a comparative study has been conducted to find the most suitable combination to produce desired sulphur nanoparticles, using different acidic mediums along with different green surfactants. An eco-friendly and benign method has been discussed here for the synthesis of SNPs using two different acidic mediums (citric acid and oxalic acid). Catharanthus roseus and Aloevera plant extracts have been taken as stabilising and capping agents in the process. A series of characterisation techniques have been carried out such as scanning electron microscopy (SEM), x-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FTIR) and UV–vis for morphological, structural and optical study. UV–vis absorption spectra have shown that the absorption peak is in the range of 287−296 nm for all the synthesised nanoparticles and confirm the formation of SNPs. XRD data has revealed the crystalline nature of SNPs and the smallest crystalline size of 69 nm for oxalic acid with Aloevera leaf extract. It has been observed that the size reduces due to the bonding/ adsorption of biomolecules at the surface of SNPs. Aloevera leaf extract gives the maximum adsorption as conveyed by the FTIR graph. The morphology and uniformity of SNPs are observed using the scanning electron microscope. SNPs synthesised using citric acid as a reducing agent have been found spherical in shape while the ones synthesised using oxalic acid are hexagonal. The study reveals that the SNPs synthesised using Aloevera and oxalic acid are more uniform and monodispersed.

Preparation and structural regulation of macroporous agarose microspheres for highly efficient adsorption of giant biomolecules

Preparation and structural regulation of macroporous agarose microspheres for highly efficient adsorption of giant biomolecules

The Janus of Protein Corona on nanoparticles for tumor targeting, immunotherapy and diagnosis.

The therapeutics based on nanoparticles (NPs) are considered as the promising strategy for tumor detection and treatment. However, one of the most challenges is the adsorption of biomolecules on NPs after their exposition to biological medium, leading unpredictable in vivo behaviors. The interactions caused by protein corona (PC) will influence the biological fate of NPs in either negative or positive ways, including (i) blood circulation, accumulation and penetration of NPs at targeting sites, and further cellular uptake in tumor targeting delivery; (ii) interactions between NPs and receptors on immune cells for immunotherapy. Besides, PC on NPs could be utilized as new biomarker in tumor diagnosis by identifying the minor change of protein concentration led by tumor growth and invasion in blood. Herein, the mechanisms of these PC-mediated effects will be introduced. Moreover, the recent advances about the strategies will be reviewed to reduce negative effects caused by PC and/or utilize positive effects of PC on tumor targeting, immunotherapy and diagnosis, aiming to provide a reasonable perspective to recognize PC with their applications.

Near-Infrared Light-Remote Localized Drug Delivery Systems Based on Zwitterionic Polymer Nanofibers for Combination Therapy.

Localized drug delivery systems (LDDS) have gained great interests because they can directly treat the tumors and minimize systematic toxicity, and maximize drug action by controlling release precisely at the tumor site. However, the resistance of the non-specific adsorption of biomolecules is also important to alleviate the inflammatory reactions and avoid the decrease in performance of LDDS. In this study, we develop a near infrared (NIR) light-triggered nanofibrous delivery system consisting of zwitterionic poly(2-methacryloyloxyethyl phosphorylcholine)-b-poly(ε-caprolactone) (PMPC-b-PCL) encapsulated with indocyanine green (ICG) and doxorubicin (DOX) for dual photothermal therapy and chemotherapy. The nanofibrous mat shows hydrophilic characteristics and good antifouling performance. Under mild NIR irradiation, ICG could convert NIR light into thermal energy that elevates the surrounding temperature above 45 °C. This thermal energy also markedly accelerates the DOX release from the nanofibrous mat due to softening of the nanofibers, indicating the drug release could be controlled and switched on/off by light-triggering. Moreover, this light-triggered thermal energy and releasing behavior contribute to enhancing the cell lethality. Intracellular DOX distribution confirms the more drugs release upon light irradiation. All results demonstrate the developed light-triggered drug release nanofibers as LDDS are biocompatible and antifouling as well as has the superior combinational chemotherapy/photothermal therapy.

Surface Plasmon Resonance Sensor Based on Double-Sided Polished Microstructured Optical Fiber Coated With Graphene-on-Silver Layers

We propose a concept of surface plasmon resonance sensor based on double-sided polished microstructured optical fiber coated with graphene-on-silver layers. The silver films on the polishing planes are covered with multilayer graphene which can prevent the oxidation of silver and enhance the adsorption of biomolecules. The sensing performance of the proposed sensors with polishing planes angle of 0&#x00B0;, 60&#x00B0; and 120&#x00B0;, are investigated by using both wavelength and amplitude interrogations. Our numerical results demonstrate that increasing the size of the air hole in the core area can effectively improve the wavelength and maximum amplitude sensitivities. Moreover, growing number layer of graphene can increase wavelength sensitivity, whereas decrease the maximum amplitude sensitivity.

Complexation on the Oxide Surfaces: Adsorption of Biomolecules from Aqueous Solutions: A Review

Complexation on the Oxide Surfaces: Adsorption of Biomolecules from Aqueous Solutions: A Review

Biocompatible surface functionalization architecture for a diamond quantum sensor

Quantum metrology enables some of the most precise measurements. In the life sciences, diamond-based quantum sensing has led to a new class of biophysical sensors and diagnostic devices that are being investigated as a platform for cancer screening and ultrasensitive immunoassays. However, a broader application in the life sciences based on nanoscale NMR spectroscopy has been hampered by the need to interface highly sensitive quantum bit (qubit) sensors with their biological targets. Here, we demonstrate an approach that combines quantum engineering with single-molecule biophysics to immobilize individual proteins and DNA molecules on the surface of a bulk diamond crystal that hosts coherent nitrogen vacancy qubit sensors. Our thin (sub-5 nm) functionalization architecture provides precise control over the biomolecule adsorption density and results in near-surface qubit coherence approaching 100 μs. The developed architecture remains chemically stable under physiological conditions for over 5 d, making our technique compatible with most biophysical and biomedical applications.

Novel adsorption approach for the enrichment of R-Phycoerythrin from marine macroalga Gelidium pusillum

R-Phycoerythrin is a fluorescent and commercially valuable pigment protein present in algae. The extraction, purification and concentration of such biomolecules is a challenge for processing industries. In the present work, enrichment of R-Phycoerythrin was attempted by selective adsorption of other contaminant biomolecules from extract of algal biomass. Different adsorbents (zeolite, molecular sieve, ammonium Y zeolite, silver-exchanged zeolite, mesoporous carbon) and nanoparticles (zinc oxide, graphene oxide, gold and silver) were explored for this purpose. Process conditions such as buffer pH (5, 6, 7 and 8), ionic strength (0.1, 0.35, 0.6, 0.85 and 1.1) and adsorbent levels (w/w) were optimized. Optimization resulted in enrichment of pre-treated R-Phycoerythrin by 3.31 fold with 73.36% yield using zeolite and 2.10 fold with 98.91% yield using gold nanoparticles. This work demonstrates the efficacy of adsorbents and nanoparticles as possible alternatives for enrichment and purification of R-Phycoerythrin with appreciable yield.

Design Strategy for Nanostructured Arrays of Metallodielectric Cuboids to Systematically Tune the Optical Response and Eliminate Spurious Bulk Effects in Plasmonic Biosensors

Plasmonic biosensors are a powerful tool for studying molecule adsorption label-free and with high sensitivity. Here, we present a systematic study on the optical properties of strictly regular nanostructures composed of metallodielectric cuboids with the aim to deliberately tune their optical response and improve their biosensing performance. In addition, the patterns were tested for their potential to eliminate spurious effects from sensor response, caused by refractive index changes in the bulk solution. Shifts in the plasmonic spectrum are exclusively caused by the adsorbing molecules. For this purpose, nanopatterns of interconnected and separated cubes with dimensions ranging from 150 to 600 nm have been fabricated from poly(methyl methacrylate) using electron-beam lithography followed by metallization with gold. It is shown that a small lateral pattern size, a high aspect ratio, and short connection lengths are favorable to generate extinction spectra with well-separated and pronounced peaks. Furthermore, for selected nanostructures, we have been able to identify reflection angles for which the influence of the bulk refractive index on the position of the plasmonic peaks is negligible. It is shown that sensor operation under these angles enables monitoring of in situ biomolecule adsorption with high sensitivity providing a promising tool for high-throughput applications.