Bovine serum albumin adsorption on SiO2 and TiO2 nanoparticle surfaces at circumneutral and acidic pH: A tale of two nano-bio surface interactions

Influence of natural organic matter on the aggregation dynamics of biochar colloids derived from various feedstocks

Abundant biochar colloids (BCs) produced from a wide range of feedstocks, resulting from forest fires, agricultural production, and environmental restoration, exhibit varying aggregation behaviors influenced by feedstock type and natural organic matter. However, the impact of natural organic matter on the colloidal stability of BCs derived from different feedstocks remains poorly understood. In this study, six selected biochars were derived from various feedstocks as follows: sewage sludge (SS), rice husk (RH), oil seed rape straw pellets (OSR), wheat straw pellets (WS), miscanthus straw pellets (MS) and softwood pellets (SW). The colloidal stability of BCs, with the exogenous addition of organic matter, was further determined. The order of critical coagulation concentrations (CCCs) of BCs with the presence of humic acid (HA) was as follows: RH (989.48 mM) < MS (1084.69 mM) < SS (1149.76 mM) < WS (1338.99 mM) < OSR (2402.98 mM) < SW (3151.32 mM). This order was significantly positively correlated with the specific surface area and negatively correlated with the ash content of the bulk biochar. Compared to HA, bovine serum albumin (BSA) more effectively inhibited the aggregation behavior of BCs due to steric hindrance. The initial aggregation rate constant (k) of BCs at 3000 mM NaCl was as follows: MS (0.238 nm/s) > OSR (0.142 nm/s) > WS (0.128 nm/s) > SS (0.126 nm/s) > RH (0.118 nm/s) > SW (0.112 nm/s). The stabilizing effects of BSA on biochar colloids were independent of the physicochemical properties of bulk biochar. In the presence of BSA, a thin layer of protein corona significantly enhanced the stability of biochar colloids, particularly the BCs derived from MS. Our results underscore the importance of considering feedstock resources and natural organic matter type when assessing the aggregation and potential risks of BCs in aquatic systems.

A Comparative Study on the Interaction Between Protein and PET Micro/Nanoplastics: Structural and Surface Characteristics of Particles and Impacts on Lung Carcinoma Cells (A549) and Staphylococcus aureus

The interaction between particles and proteins is a key factor determining the toxicity responses of particles. Therefore, this study aimed to examine the interaction between the emerging pollutant polyethylene terephthalate micro/nanoplastics from water bottles with bovine serum albumin. The physicochemical characteristics of micro/nanoplastics were investigated using nuclear magnetic resonance, x-ray diffraction, Fourier transform infrared, dynamic light scattering, and x-ray energy dispersive spectroscopy after exposure to various concentrations and durations of protein. Furthermore, the impact of protein-treated micro/nanoplastics on biological activities was examined using the mitochondrial activity and membrane integrity of A549 cells and the activity and biofilm production of Staphylococcus aureus. The structural characteristics of micro/nanoplastics revealed an interaction with protein. For instance, the assignment of protein-related new proton signals (e.g., CH2, methylene protons of CH2O), changes in available protons s (e.g., CH and CH3), crystallinity, functional groups, elemental ratios, zeta potentials (-11.3 ± 1.3 to -12.4 ± 1.7 to 25.5 ± 2.3 mV), and particle size (395 ± 76 to 496 ± 60 to 866 ± 82 nm) of micro/nanoplastics were significantly observed after protein treatment. In addition, the loading (0.012-0.027 mM) and releasing (0.008-0.013 mM) of protein also showed similar responses with structural characteristics. Moreover, the cell-based responses were changed regarding the structural and surface characteristics of micro/nanoplastics and the loading efficiencies of protein. For example, insignificant mitochondrial activity (2%-10%) and significant membrane integrity (12%-28%) of A549 cells increased compared with control, and reductions in bacterial activity (5%-40%) in many cases and biofilm production specifically at low dose of all treatment stages (13%-46% reduction) were observed.

Mesoscopic Model for Reversible Adsorption Stage of Albumin and Fibrinogen on TiO2 Surface

The competitive behavior of proteins in the reversible adsorption stage plays a crucial role in determining the composition of the protein layer and the subsequent biological responses to the biomaterial. However, such competitive adsorption is a mesoscopic process at physiological protein concentration, and neither a macroscopic experiment nor microscopic MD (molecular dynamics) simulation is suitable to clarify it. Here, we proposed a mesoscopic DPD (dissipative particle dynamics) model to illustrate the competitive process of albumin and fibrinogen on TiO2 surface with its parameters deduced from our previous MD simulation, and proved the model well retained the diffusion and adsorption properties of proteins in the competitive adsorption on the plane surface. We then applied the model to the competitive adsorption on the surfaces with different nanostructures and observed that when the nanostructure size is much larger than that of protein, the increase in surface area is the main influencing factor; when the nanostructure size is close to that of protein, the coordination between the nanostructure and the size and shape of protein significantly affects the competitive adsorption process. The model has revealed many mechanical phenomena observed in previous experimental studies and has the potential to contribute to the development of high-performance biomaterials.

Nanoparticle-Assisted Liquid Crystal Droplet Sensors Enable Analysis of Low-Concentration Species in Aqueous Medium

We introduce nanoparticle-assisted liquid crystal (LC) droplet-based sensors that allow determination of low-level concentrations of aqueous soluble species. The silica nanoparticles functionalized with mixed monolayers composed of two distinct groups, hydrophobic alkane tail- and charged group-terminated silanes, facilitated ternary physical interactions between the model analytes (methylene blue (MB) or methyl orange (MO)) and the nematic mesogens 5CB (4-cyano-4'-pentylbiphenyl), and the interfacial species of the nanoparticle. The response of the LC droplets was measured upon nanoparticle adsorption as a function of analyte concentration, which was characterized by the optical determination of the configuration distributions of the LC droplets. We highlight the importance of the charging and the composition of the nanoparticle interfaces for analytical purposes that allow accurate determination of the concentration of the analytes on the order of 0.01 ppb. Such a low concentration corresponds to a low interfacial coverage of nanoparticles, indicating the promisingly high sensitivity of the sensor platform to target analytes. Distinct from the past examples of the LC-based sensors, the nanoparticle-assisted LC sensors allow detection of the species that do not directly cause an ordering transition at the LC-water interfaces, which allow a broader range of analytical targets. The sensor platform that we report herein can be easily tunable for a range of target molecules and will find use in the determination of a wide range of micropollutants in aqueous environments.

Transformation of Nano-Size Titanium Dioxide Particles in the Gastrointestinal Tract and Its Role in the Transfer of Nanoparticles through the Intestinal Barrier

In this work, the size transformation of the TiO2 nanofraction from pharmaceutical grade E171 powder was studied during its transit through the gastrointestinal tract (GIT). It was shown that pharmaceutical-grade TiO2 powder contained about 0.68% (w/w) of particles smaller than 240 nm in diameter. In the observed GIT transit process the TiO2 nanoparticles were agglomerated up to 150-200 nm in simulated salivary fluid, with gradual agglomerate enlargement up to 300-600 nm and more than 1 micron in simulated gastric fluid. In the intestinal fluid the reverse process occurred, involving a decrease of agglomerates accompanied by the formation of a small fraction with ~50 nm average size. This fraction can be further involved in the histohematic transport process. The acidity degree (pH) and mineral composition of solutions, as well as the transit speed along the gastrointestinal tract, influence the nature of the particle transformation significantly. The rapid passing between the gastrointestinal tract sections creates conditions for a decrease in part of the TiO2 particles, up to 100 nm, and may be associated with the violation of the structural and functional integrity of the intestinal mucus layer.

Characterizing the interaction between micro(nano)plastics and simulated body fluids and their impact on human lung epithelial cells

Micro(nano)plastics are considered an emerging threat to human health because they can interact with biological systems. In fact, these materials have already been found in the human body, such as in the lungs. However, limited data are available on the behavior of these materials under biological conditions and their impact on human cells, specifically on alveolar epithelial cells. In this study, micro(nano)plastics were exposed to various simulated biological fluids (artificial lysosomal fluids and Gamble's solution) for 2-80 h. Pristine and treated plastic particles were characterized based on their surface chemistry, zeta potentials, and elemental composition. Various toxicological endpoints (mitochondrial membrane potential, lactate dehydrogenase, protein, and antioxidant levels) were examined using A549 lung carcinoma cells. The surface characteristics of the treated micro(nano)plastics and the toxicological endpoints of A549 cells were found to be influenced by the simulated biological media, specifically with high concentrations of the treated micro(nano)plastics and increasing exposure under biological conditions. Moreover, the toxicological endpoints were strongly linked to the chemistry of plastics and included multiple processes in response to the plastics; different biological pathways were obtained in artificial lysosomal fluid and Gamble's solution.

Interactions between proteins and cellulose in a liquid crystalline media: Design of a droplet based experimental platform

Model systems are needed to provide controlled environment for the understanding of complex phenomena. Interaction between polysaccharides and proteins in dense medium are involved in numerous complex systems such as biomass conversion or plant use for food processing or biobased materials. In this work, cellulose nanocrystals (CNCs) were used to study proteins in a dense and organized cellulosic environment. This environment was designed within microdroplets using a microfluidic setup, and applied to two proteins, bovine serum albumin (BSA) and a GH7 endoglucanase, relevant to food and plant science, respectively. The CNC at 56.5 g/L organized in liquid crystalline structure and the distribution of the proteins was probed using synchrotron deep-UV radiation. The proteins were homogeneously distributed throughout the volume, but BSA significantly disturbed the droplet global organization, preferring partition in hydrophilic external micelles. In contrast, GH7 partitioned with the CNCs showing stronger non-polar interaction but without disruption of the system organization. Such results pave the road for the development of more complex polysaccharides - proteins in-vitro models.

Oxide- and Silicate-Water Interfaces and Their Roles in Technology and the Environment

Interfacial reactions drive all elemental cycling on Earth and play pivotal roles in human activities such as agriculture, water purification, energy production and storage, environmental contaminant remediation, and nuclear waste repository management. The onset of the 21st century marked the beginning of a more detailed understanding of mineral aqueous interfaces enabled by advances in techniques that use tunable high-flux focused ultrafast laser and X-ray sources to provide near-atomic measurement resolution, as well as by nanofabrication approaches that enable transmission electron microscopy in a liquid cell. This leap into atomic- and nanometer-scale measurements has uncovered scale-dependent phenomena whose reaction thermodynamics, kinetics, and pathways deviate from previous observations made on larger systems. A second key advance is new experimental evidence for what scientists hypothesized but could not test previously, namely, interfacial chemical reactions are frequently driven by "anomalies" or "non-idealities" such as defects, nanoconfinement, and other nontypical chemical structures. Third, progress in computational chemistry has yielded new insights that allow a move beyond simple schematics, leading to a molecular model of these complex interfaces. In combination with surface-sensitive measurements, we have gained knowledge of the interfacial structure and dynamics, including the underlying solid surface and the immediately adjacent water and aqueous ions, enabling a better definition of what constitutes the oxide- and silicate-water interfaces. This critical review discusses how science progresses from understanding ideal solid-water interfaces to more realistic systems, focusing on accomplishments in the last 20 years and identifying challenges and future opportunities for the community to address. We anticipate that the next 20 years will focus on understanding and predicting dynamic transient and reactive structures over greater spatial and temporal ranges as well as systems of greater structural and chemical complexity. Closer collaborations of theoretical and experimental experts across disciplines will continue to be critical to achieving this great aspiration.

Impact of pH on the Formation and Properties of Whey Protein Coronas around TiO2 Nanoparticles

In aqueous media, titanium dioxide (TiO₂) nanoparticles can interact with proteins in their environment and form a protein corona. The pH of the aqueous media affects the structure and properties of the protein corona, and currently there is a lack of understanding of the effects of pH on the characteristics of protein coronas. In this study, we examined the impact of pH (2-11) on the structural and physicochemical properties of whey protein coronas formed around TiO₂ nanoparticles. The pH of the solution influenced the structure of whey protein molecules, especially around their isoelectric point. Thermogravimetric and quartz crystal microbalance analyses showed that the adsorption capacity of the whey proteins was the largest at their isoelectric points and the lowest under highly acidic or alkaline conditions. The majority of the proteins were tightly bound to the nanoparticle surfaces, forming a hard corona. The influence of solution pH on protein corona properties was mainly attributed to its impact on the electrostatic forces in the system, which impacted the protein conformation and interactions. This study provides useful insights into the influence of pH on the formation and properties of protein coronas around inorganic nanoparticles, which may be important for understanding the gastrointestinal and environmental fates.

Analysis of micro- and nanoscale heterogeneities within environmentally relevant thin films containing biological components, oxyanions and minerals using AFM-PTIR spectroscopy

Minerals in groundwater interact with various chemical and biological species including organic matter, proteins, and prevalent oxyanions, resulting in surface coatings and thin films of these different components. Surface interactions and the surface adsorption of these components on both oxide and oxyhydroxide iron surfaces have been widely investigated using a variety of spectroscopic methods. Despite these numerous studies, there still remains uncertainty with respect to interactions between these individual components, as well as heterogeneities and phase segregations within these thin films. In this study, we investigate mixtures containing Fe-containing minerals, proteins, and oxyanions to better understand surface interactions and phase segregation using Atomic Force Microscopy PhotoThermal Infrared (AFM-PTIR) spectroscopy. The results of this study show that AFM-PTIR spectroscopy can identify both nano- and microscale heterogeneities present within these thin films that are difficult to discern with other more conventional techniques such as ATR-FTIR spectroscopy due to phase segregation and mineral surface interactions. Overall, AFM-PTIR spectroscopy provides insights into multi-component environmental films that are difficult to uncover using other methodologies. This method has the potential to differentiate between bound and unbound toxic species as well as biological components, including environmental DNA, which can be used to assess the fate and transport of these species in the environment.

Nanoparticle protein corona: from structure and function to therapeutic targeting

Nanoparticle (NP)-based therapeutics have ushered in a new era in translational medicine. However, despite the clinical success of NP technology, it is not well-understood how NPs fundamentally change in biological environments. When introduced into physiological fluids, NPs are coated by proteins, forming a protein corona (PC). The PC has the potential to endow NPs with a new identity and alter their bioactivity, stability, and destination. Additionally, the conformation of proteins is sensitive to their physical and chemical surroundings. Therefore, biological factors and protein-NP-interactions can induce changes in the conformation and orientation of proteins in vivo. Since the function of a protein is closely connected to its folded structure, slight differences in the surrounding environment as well as the surface characteristics of the NP materials may cause proteins to lose or gain a function. As a result, this can alter the downstream functionality of the NPs. This review introduces the main biological factors affecting the conformation of proteins associated with the PC. Then, four types of NPs with extensive utility in biomedical applications are described in greater detail, focusing on the conformation and orientation of adsorbed proteins. This is followed by a discussion on the instances in which the conformation of adsorbed proteins can be leveraged for therapeutic purposes, such as controlling protein conformation in assembled matrices in tissue, as well as controlling the PC conformation for modulating immune responses. The review concludes with a perspective on the remaining challenges and unexplored areas at the interface of PC and NP research.

Differential Surface Interactions and Surface Templating of Nucleotides (dGMP, dCMP, dAMP, and dTMP) on Oxide Particle Surfaces

The fate of biomolecules in the environment depends in part on understanding the surface chemistry occurring at the biological-geochemical (bio-geo) interface. Little is known about how environmental DNA (eDNA) or smaller components, like nucleotides and oligonucleotides, persist in aquatic environments and the role of surface interactions. This study aims to probe surface interactions and adsorption behavior of nucleotides on oxide surfaces. We have investigated the interactions of individual nucleotides (dGMP, dCMP, dAMP, and dTMP) on TiO₂ particle surfaces as a function of pH and in the presence of complementary and noncomplementary base pairs. Using attenuated total reflectance-Fourier transform infrared spectroscopy, there is an increased number of adsorbed nucleotides at lower pH with a preferential interaction of the phosphate group with the oxide surface. Additionally, differential adsorption behavior is seen where purine nucleotides are preferentially adsorbed, with higher surface saturation coverage, over their pyrimidine derivatives. These differences may be a result of intermolecular interactions between coadsorbed nucleotides. When the TiO₂ surface was exposed to two-component solutions of nucleotides, there was preferential adsorption of dGMP compared to dCMP and dTMP, and dAMP compared to dTMP and dCMP. Complementary nucleotide base pairs showed hydrogen-bond interactions between a strongly adsorbed purine nucleotide layer and a weaker interacting hydrogen-bonded pyrimidine second layer. Noncomplementary base pairs did not form a second layer. These results highlight several important findings: (i) there is differential adsorption of nucleotides; (ii) complementary coadsorbed nucleotides show base pairing with a second layer, and the stability depends on the strength of the hydrogen bonding interactions and; (iii) the first layer coverage strongly depends on pH. Overall, the importance of surface interactions in the adsorption of nucleotides and the templating of specific interactions between nucleotides are discussed.

Interaction of nanoplastics with simulated biological fluids and their effect on the biofilm formation

Over the last decade, it has become clear that the pollution by plastic debris presents global societal, environmental, and human health challenges. Moreover, humans are exposed to plastic particles in daily life and very limited information is available concerning human health, especially interactions with biological fluids. Therefore, the aim of this study is to investigate the interaction of plastic particles with simulated biological fluids (e.g., artificial saliva, artificial lysosomal fluid, phagolysosomal simulant fluid, and Gamble's solution) using various exposure stages (2 h to 80 h) and the effect of plastic particles on the formation of Staphylococcus aureus biofilms under simulated biological conditions. The plastic particles incubating various simulated biological fluids were characterized using surface functional groups, zeta potentials, and elemental composition. The results indicated that functional group indices (C-O, C = O, C-H, C = C, C-N, S = O, and OH) decreased compared to the control group during the incubation periods, except for the hydroxyl group index. The FTIR results showed that the hydroxyl group formed with the artificial lysosomal fluid, the phagolysosomal simulant fluid, and Gamble's solution. With the impact of the declining functional groups, the zeta potentials were more negative than in the control. Moreover, EDX results showed the release of the components in the particles with the interaction of simulated biological fluids as well as new components like P and Ca introduced to the particles. The biofilms were formed in the presence of nanoplastic particles under both controlled conditions and simulated biological conditions. The amount of biofilm formation was mainly affected by the surface characteristics under simulated biological conditions. In addition, the biofilm characteristics were influenced by the O/C and N/C ratios of the plastic particles with the impact of simulated biological fluids.

The electrostatic confinement of aquated monocationic Gd(III) complex-molecules within the inner core of porous silica nanoparticles creates a highly efficient T1 contrast agent for magnetic resonance imaging

Contrast-agent enhanced magnetic resonance imaging (MRI) has been under continuous investigation for the conspicuous imaging of lesions and the early-stage detection of tumors. To achieve the development of a T₁-weighted contrast agent with a high relaxivity value, herein, porous silica nanoparticles that had internalized about 20 aquated cationic Gd(III) complexes (1) of the hexadentate hydroxyethyl-appended picolinate-based ligand H₂hbda were demonstrated. Complex 1 exhibited a longitudinal relaxivity value per mM Gd(III) ions, r₁, of 9.05 mM^-1 s^-1 (pH 7.4, 37 °C, 1.41 T), which increased to 86.41 mM^-1 s^-1 because of the grafting of complex 1 in the inner core of porous silica nanospheres through electrostatic interactions between the anionic silica surface and the cationic complex 1 molecules. A further augmentation in the relaxivity value to 118.32 mM^-1 s^-1 was realized because of the interaction of the complex 1@SiO₂NPs with serum albumin protein. The synthesized nanosystem was impervious to physiologically available anions (HPO₄^2- and HCO₃^1-) and also kinetically inert, as evidenced via a transmetallation experiment in the presence of Zn(II) ions. The developed complex-incorporated nanomaterial was bio- and hemo-compatible. Cellular uptake measurements employing HeLa cells and the concentration-dependent enhancement in the brightness of in vitro phantom images, recorded under a clinical scanner at 1.5 T, demonstrated that the developed biocompatible 1@SiO₂NP complex has promising diagnostic applications as a T₁-weighted MRI contrast agent.

The effects of protein corona on in vivo fate of nanocarriers

With the emerging advances in utilizing nanocarriers for biomedical applications, a molecular-level understanding of the in vivo fate of nanocarriers is necessary. After administration into human fluids, nanocarriers can attract proteins onto their surfaces, forming an assembled adsorption layer called protein corona (PC). The formed PC can influence the physicochemical properties and subsequently determine nanocarriers' biological behaviors. Therefore, an in-depth understanding of the features and effects of the PC on the nanocarriers' surface is the first and most important step towards controlling their in vivo fate. This review introduces fundamental knowledge such as the definition, formation, composition, conformation, and characterization of the PC, emphasizing the in vivo environmental factors that control the PC formation. The effect of PC on the physicochemical properties and thus biological behaviors of nanocarriers was then presented and thoroughly discussed. Finally, we proposed the design strategies available for engineering PC onto nanocarriers to manipulate them with the desired surface properties and achieve the best biomedical outcomes.

Engineering the hydroxyl content on aluminum oxyhydroxide nanorod for elucidating the antigen adsorption behavior

The interaction between the aluminum salt-based adjuvants and the antigen in the vaccine formulation is one of the determining factors affecting the immuno-potentiation effect of vaccines. However, it is not clear how the intrinsic properties of the adjuvants could affect this interaction, which limits to benefit the improvement of existing adjuvants and further formulation of new vaccines. Here, we engineered aluminum oxyhydroxide (AlOOH) nanorods and used a variety of antigens including hepatitis B surface antigen (HBsAg), SARS-CoV-2 spike protein receptor-binding domain (RBD), bovine serum albumin (BSA) and ovalbumin (OVA) to identify the key physicochemical properties of adjuvant that determine the antigen adsorption at the nano-bio interface between selected antigen and AlOOH nanorod adjuvant. By using various physicochemical and biophysical characterization methods, it was demonstrated that the surface hydroxyl contents of AlOOH nanorods affected the adsorptive strength of the antigen and their specific surface area determined the adsorptive capacity of the antigen. In addition, surface hydroxyl contents had an impact on the stability of the adsorbed antigen. By engineering the key intrinsic characteristics of aluminum-based adjuvants, the antigen adsorption behavior with the aluminum adjuvant could be regulated. This will facilitate the design of vaccine formulations to optimize the adsorption and stability of the antigen in vaccine.

Effect of protein adsorption on the dissolution kinetics of silica nanoparticles

Nanoparticulate systems in the presence of proteins are highly relevant for various biomedical applications such as photo-thermal therapy and targeted drug delivery. These involve a complex interplay between the charge state of nanoparticles and protein, the resulting protein conformation, adsorption equilibrium and adsorption kinetics, as well as particle dissolution. SiO₂ is a common constituent of bioactive glasses used in biomedical applications. In this context, the dissolution behavior of silica particles in the presence of a model protein, bovine serum albumin (BSA), at physiologically relevant pH conditions was studied. Sedimentation analysis using an analytical ultracentrifuge showed that BSA in the supernatant solution is not affected by the presence of silica nanoparticles. However, zeta potential measurements revealed that the presence of the protein alters the particles' charge state. Adsorption and dissolution studies demonstrated that the presence of the protein significantly enhances the dissolution kinetics via interactions of positively charged amino acids in the protein with the negative silica surface and interaction of BSA with dissolved silicate species. Our study provides comprehensive insights into the complex interactions between proteins and oxide nanoparticles and establishes a reliable protocol paving the way for future investigations in more complex systems involving biological solutions as well as bioactive materials.

The interfacial interactions of nanomaterials with human serum albumin

The fates of nanomaterials (NMs) in vivo are greatly dependent on their interactions with human serum proteins. However, the interfacial molecular details of NMs-serum proteins are still difficult to be probed. Herein, the molecular interaction details of human serum albumin (HSA) with Au and SiO₂ nanoparticles have been systematically interrogated and compared by using lysine reactivity profiling mass spectrometry (LRP-MS). We demonstrated the biocompatibility of Au is better than SiO₂ nanoparticles and the NMs surface charge state played a more important role than particle size in the combination of NMs-HSA at least in the range of 15-40 nm. Our results will contribute to the fundamental mechanism understanding of NMs-serum protein interactions as well as the NMs rational design.

Facile synthesis of low toxicity iron oxide/TiO2 nanocomposites with hyperthermic and photo-oxidation properties

The present study aimed to assess the feasibility of developing low-cost multipurpose iron oxide/TiO2 nanocomposites (NCs) for use in combined antitumor therapies and water treatment applications. Larger size (≈ 100 nm) iron oxide nanoparticles (IONPs) formed magnetic core-TiO2 shell structures at high Fe/Ti ratios and solid dispersions of IONPs embedded in TiO2 matrices when the Fe/Ti ratio was low. When the size of the iron phase was comparable to the size of the crystallized TiO2 nanoparticles (≈ 10 nm), the obtained nanocomposites consisted of randomly mixed aggregates of TiO2 and IONPs. The best inductive heating and ROS photogeneration properties were shown by the NCs synthesized at 400 °C which contained the minimum amount of α-Fe2O3 and sufficiently crystallized anatase TiO2. Their cytocompatibility was assessed on cultured human and murine fibroblast cells and analyzed in relation to the adsorption of bovine serum albumin from the culture medium onto their surface. The tested nanocomposites showed excellent cytocompatibility to human fibroblast cells. The results also indicated that the environment (i.e. phosphate buffer or culture medium) used to disperse the nanomaterials prior to performing the viability tests can have a significant impact on their cytotoxicity.

Rational design of smart nano-platforms based on antifouling-nanomaterials toward multifunctional bioanalysis

The ability to design nanoprobe devices with the capability of quantitative/qualitative operation in complex media will probably underpin the main upcoming progress in healthcare research and development. However, the biomolecules abundances in real samples can considerably alter the interface performance, where unwanted adsorption/adhesion can block signal response and significantly decrease the specificity of the assay. Herein, this review firstly offers a brief outline of several significances of fabricating high-sensitivity and low-background interfaces to adjust various targets' behaviors induced via bioactive molecules on the surface. Besides, some important strategies to resist non-specific protein adsorption and cell adhesion, followed by imperative categories of antifouling reagents utilized in the construction of high-performance solid sensory interfaces, are discussed. The next section specifically highlights the various nanocomposite probes based on antifouling-nanomaterials for electrode modification containing carbon nanomaterials, noble metal nanoparticles, magnetic nanoparticles, polymer, and silicon-based materials in terms of nanoparticles, rods, or porous materials through optical or chemical strategies. We specially outline those nanoprobes that are capable of identification in complex media or those using new constructions/methods. Finally, the necessity and requirements for future advances in this emerging field are also presented, followed by opportunities and challenges.

Formation and physicochemical properties of glycogen phosphorylase in complex with a cationic polyelectrolyte

The accumulation of rabbit muscle glycogen phosphorylase b (RMGPb) in electrostatic complexes with the cationic polyelectrolyte poly 2-(dimethylamino) ethyl methacrylate in its quenched form (QPDMAEMA) was studied in two buffer solutions. In the N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid (BES) buffer, large complexes of RMGPb-QPDMAEMA were formed which adopted smaller sizes as QPDMAEMA concentration increased. However, in N-(2-hydroxyethyl)piperazine-N'-(2-ethanesulfonic acid) (HEPES) buffer, the hydrodynamic radius of the formed complexes gradually increased as the polymer concentration increased. Zeta potential measurements (ζ_p) showed that RMGPb significantly changed the ζ_p of the QPDMAEMA aggregates. Fluorescence studies showed that the interaction between RMGPb and QPDMAEAMA was enhanced as polymer concentration increased. Specifically, 8-anilinonaphthalene-1-sulfonic acid (ANS) fluorescence indicated that in the BES buffer the aggregates became denser as more QPDMAEMA was added, while in the HEPES buffer the density of the formed structures decreased. RMGPb's secondary structure was examined by Attenuated Total Reflection - Fourier Transform Infrared (ATR-FTIR) and Circular Dichroism (CD) showing that QPDMAEMA interaction with RMGPb does not induce any changes to the secondary structure of the enzyme. These observations suggest that cationic polyelectrolytes may be utilized for the formulation of RMGPb in multifunctional nanostructures and be further exploited in innovative biotechnology applications and bioinspired materials development.

Progress in infrared spectroscopy as an efficient tool for predicting protein secondary structure

Infrared (IR) spectroscopy is a highly sensitive technique that provides complete information on chemical compositions. The IR spectra of proteins or peptides give rise to nine characteristic IR absorption bands. The amide I bands are the most prominent and sensitive vibrational bands and widely used to predict protein secondary structures. The interference of H₂O absorbance is the greatest challenge for IR protein secondary structure prediction. Much effort has been made to reduce/eliminate the interference of H₂O, simplify operation steps, and increase prediction accuracy. Progress in sampling and equipment has rendered the Fourier transform infrared (FTIR) technique suitable for determining the protein secondary structure in broader concentration ranges, greatly simplifying the operating steps. This review highlights the recent progress in sample preparation, data analysis, and equipment development of FTIR in A/T mode, with a focus on recent applications of FTIR spectroscopy in the prediction of protein secondary structure. This review also provides a brief introduction of the progress in ATR-FTIR for predicting protein secondary structure and discusses some combined IR methods, such as AFM-based IR spectroscopy, that are used to analyze protein structural dynamics and protein aggregation.

ATR FTIR Study of the Interaction of TiO2 Nanoparticle Films with β-Lactoglobulin and Bile Salts

The technique of in situ particle film attenuated total reflection Fourier transform infrared spectroscopy (ATR FTIR) has been used to probe the adsorption and coadsorption (sequential) of a common food protein (β-lactoglobulin, BLG) and two representative bile salts (taurocholic acid and glycocholic acid, abbreviated as TCA and GCA) onto the surface of titanium dioxide (TiO₂) nanoparticles. Evaluating of binding interactions between commonly used (historically now, in some countries) food additives and food components, as well as the body's own digestion chemicals, is a critical step in understanding the role of colloidal phenomena in digestion and bioavailability. TCA is found to adsorb onto TiO₂ but without any significant ability to be retained when it is not present in the aqueous phase. GCA is also found to adsorb via two distinct binding mechanisms, with one type of adsorbed species being resistant to removal. BLG adsorbs, is irreversibly bound, and has altered conformation when adsorbed at pH 2 (stomach conditions) to the conformation when adsorbed at pH 6.5 (small intestine conditions). This altered conformation is not interface-dependent and is mirrored in the solution spectra of BLG. Sequential coadsorption studies indicate that TCA and GCA adsorb onto TiO₂ nanoparticle surfaces and display similar degrees of reversibility and binding in the presence or absence of preadsorbed BLG.

Formation and biological effects of protein corona for food-related nanoparticles

The rapid development of nanoscience and nanoengineering provides new perspectives on the composition of food materials, and has great potential for food biology research and applications. The use of nanoparticle additives and the discovery of endogenous nanoparticles in food make it important to elucidate in vivo safety of nanomaterials. Nanoparticles will spontaneously adsorb proteins during transporting in blood and a protein corona can be formed on the nanoparticle surface inside the human body. Protein corona affects the physicochemical properties of nanoparticles and the structure and function of proteins, which in turn affects a series of biological reactions. This article reviewed basic information about protein corona of food-related nanoparticles, elucidated the influence of protein corona on nanoparticles properties and protein structure and function, and discussed the effect of protein corona on nanoparticles in vivo. The effects of protein corona on nanoparticles transport, cellular uptake, cytotoxicity, and immune response were reviewed, and the reasons for these effects were also discussed. Finally, future research perspectives for food protein corona were proposed. Protein corona gives food nanoparticles a new identity, which makes proteins bound to nanoparticles undergo structural transformations that affect their recognition by receptors in vivo. It can have positive or negative impacts on cellular uptake and toxicity of nanoparticles and even trigger immune responses. Understanding the effects of protein corona have potential in evaluating the fate of the food-related nanoparticles, providing physicochemical and biological information about the interaction between proteins and foodborne nanoparticles. The review article will help to evaluate the safety of protein coronas formed on nanoparticles in food, and may provide fundamental information for understanding and controlling nanotoxicity.

TiO2@BSA nano-composites investigated through orthogonal multi-techniques characterization platform

Biocompatible coating based on bovine serum albumin (BSA) was applied on two different TiO₂ nanoparticles (aeroxide P25 and food grade E171) to investigate properties and stability of resulting TiO₂@BSA composites, under the final perspective to create a "Safe-by-Design" coating, able to uniform, level off and mitigate surface chemistry related phenomena, as naturally occurring when nano-phases come in touch with proteins enriched biological fluids. The first step towards validating the proposed approach is a detailed characterization of surface chemistry with the quantification of amount and stability of BSA coating deposited on nanoparticles' surfaces. At this purpose, we implemented an orthogonal multi-techniques characterization platform, providing important information on colloidal behavior, particle size distribution and BSA-coating structure of investigated TiO₂ systems. Specifically, the proposed orthogonal approach enabled the quantitative determination of bound and free (not adsorbed) BSA, a key aspect for the design of intentionally BSA coated nano-structures, in nanomedicine and, overall, for the control of nano-surface reactivity. In fact, the BSA-coating strategy developed and the orthogonal characterisation performed can be extended to different designed nanomaterials in order to further investigate the protein-corona formation and promote the implementation of BSA engineered coating as a strategy to harmonize the surface reactivity and minimize the biological impact.

Distinct interactions of pig and cow manure-derived colloids with TiO2 nanoparticles and their impact on stability and transport

The application of livestock manure and aquaculture wastewater into agricultural soil introduces animal manure-derived colloids into the environment. These manure-derived colloids generally contain different organic matter components and may facilitate nanoparticle transport to the subsurface. This study investigated the interaction between manure-derived colloids (cow and pig manures) and titanium dioxide (TiO₂) nanoparticles at neutral pH. The effect of this interaction on the stability, aggregation, and transport of TiO₂ in a saturated porous media was studied. Our study found that cow manure-derived colloids have many humic-like substances, and pig manure-derived colloids contain many protein components and some humic-like substances. The interactions of different manure-derived colloids with TiO₂ can affect the ζ-potential and aggregation status of TiO₂ in the aqueous system. The results showed that cow manure-derived colloids slightly increased the TiO₂ transport due to electrostatic repulsion, while pig manure-derived colloids substantially increased the TiO₂ mobility in porous media because of both electrostatic repulsion and steric hindrance. Since both animal manure and TiO₂ are ubiquitously present in the natural environment, manure-derived colloids can change the surface properties of TiO₂ and facilitate TiO₂ transport in the subsurface.

The biocompatible validity of amino acid ionic liquid mediated gold nanoparticles for enhanced activity and structural stability of papain

During the past few decades, gold nanoparticles (AuNPs) have attracted a lot of attention owing to their biomedical applications, like therapeutics and drug delivery; however, the detailed biomolecular interactions and structural alteration of naturally occurring biomolecules, such as enzymes, in AuNPs remain unknown. The effects of various additives on the thermal and structural properties, and activity of proteins/enzymes have been scavenged and communicated intensively in the literature; however, the synthesis of ionic liquid (IL) mediated AuNPs solely for the purpose of enzyme activity boosting and stability modulation has not yet been reported. In the current study, we explore the role of cholinium tryptophan [CHO][Trp] and tetraethyl tryptophan [TEA][Trp]IL-mediated gold nanoparticles (AuNPs) on the activity enhancement and structural stability of papain. Our results showed that [CHO][Trp] and [TEA][Trp]IL-mediated AuNPs efficiently increased the proteolytic activity of papain, which was increased from 100 to 206% for [CHO][Trp]IL-mediated AuNPs and enhanced from 100 to 136% in [TEA][Trp]IL-mediated AuNPs. Additionally, extended differential scanning calorimetry (DSC) results showed that these AAIL-mediated AuNPs maintained the thermal stability of papain only at lower concentration. Spectroscopic studies conclude that the tryptophan (Trp) group of papain is expanded more towards the polar environment in the presence of [CHO][Trp] as compared to [CHO][Trp]IL mediated AuNPs. The far CD spectral and deconvoluted results show that the α-helical and β-turn contents of the secondary structure of papain are preserved to a large extent; however, disruption in the β-sheet has been observed for both AAIL-mediated AuNPs. Dynamic light scattering (DLS), zeta potential and transmission electron microscopy (TEM) results illustrate the distinct interactive behavior of papain for both types of AAIL-mediated AuNPs. The immobilization of papain is higher on [CHO][Trp]AuNPs compared to [TEA][Trp]AuNPs and papain surrounds [CHO][Trp]AuNPs on all sides, which is lacking in [TEA][Trp]AuNPs.

Environmental Aspects of Oxide Nanoparticles: Probing Oxide Nanoparticle Surface Processes Under Different Environmental Conditions

Surface chemistry affects the physiochemical properties of nanoparticles in a variety of ways. Therefore, there is great interest in understanding how nanoparticle surfaces evolve under different environmental conditions of pH and temperature. Here, we discuss the use of vibrational spectroscopy as a tool that allows for in situ observations of oxide nanoparticle surfaces and their evolution due to different surface processes. We highlight oxide nanoparticle surface chemistry, either engineered anthropogenic or naturally occurring geochemical nanoparticles, in complex media, with a focus on the impact of (a) pH on adsorption, intermolecular interactions, and conformational changes; (b) surface coatings and coadsorbates on protein adsorption kinetics and protein conformation; (c) surface adsorption on the temperature dependence of protein structure phase changes; and (d) the use of two-dimensional correlation spectroscopy to analyze spectroscopic results for complex systems. An outlook of the field and remaining challenges is also presented.

Solvent-induced conformational tuning of lysozyme protein adlayers on silica surfaces: A QCM-D and LSPR study

There is broad interest in functionalizing solid surfaces with lysozyme, which is a widely studied antimicrobial protein. To date, most efforts have focused on developing more effective immobilization schemes to promote lysozyme attachment in fully aqueous conditions, while there remains an outstanding need to understand how tuning the solution-phase conformational stability of lysozyme proteins can modulate adsorption behavior and resulting adlayer properties. Inspired by the unique conformational behavior of lysozyme proteins in water-ethanol mixtures, we conducted quartz crystal microbalance-dissipation (QCM-D) and localized surface plasmon resonance (LSPR) measurements to systematically investigate the adsorption behavior of lysozyme proteins onto silica surfaces across a wide range of water-ethanol mixtures. Our findings revealed that lysozyme adsorption behavior strongly depended on the ethanol fraction in a non-monotonic fashion and this trend could be rationalized by taking into account how competing effects of water and ethanol solvation influence solution-phase protein size and conformational stability. Integrated analysis of the QCM-D and LSPR measurement trends enabled quantitative determination of the solvent mass within lysozyme adlayers, which tended to decrease at higher ethanol fractions and supported that the hydrodynamic properties of lysozyme adlayers are mainly influenced by the degree of protein conformational flexibility as opposed to solvation effects alone.

Comparing Protein Adsorption onto Alumina and Silica Nanomaterial Surfaces: Clues for Vaccine Adjuvant Development

Protein adsorption onto nanomaterial surfaces is important for various nanobiotechnology applications such as biosensors and drug delivery. Within this scope, there is growing interest to develop alumina- and silica-based nanomaterial vaccine adjuvants and an outstanding need to compare protein adsorption onto alumina- and silica-based nanomaterial surfaces. Herein, using alumina- and silica-coated arrays of silver nanodisks with plasmonic properties, we conducted localized surface plasmon resonance (LSPR) experiments to evaluate real-time adsorption of bovine serum albumin (BSA) protein onto alumina and silica surfaces. BSA monomers and oligomers were prepared in different water-ethanol mixtures and both adsorbing species consistently showed quicker adsorption kinetics and more extensive adsorption-related spreading on alumina surfaces as compared to on silica surfaces. We rationalized these experimental observations in terms of the electrostatic forces governing protein-surface interactions on the two nanomaterial surfaces and the results support that more rigidly attached BSA protein-based coatings can be formed on alumina-based nanomaterial surfaces. Collectively, the findings in this study provide fundamental insight into protein-surface interactions at nanomaterial interfaces and can help to guide the development of protein-based coatings for medical and biotechnology applications such as vaccines.

Role of Protein in Fungal Biomineralization of Copper Carbonate Nanoparticles

Biomineralization processes are of key importance in the biogeochemical cycling of metals and other elements by microorganisms, and several studies have highlighted the potential applications of nanoparticle synthesis via biomineralization. The roles played by proteins in the transformation and biologically induced biomineralization of metals by microorganisms is not well understood, despite the interactions of protein and nanoparticles at mineral interfaces attracting much interest in various emerging fields for novel biomaterial synthesis. Here, we have elucidated the association and involvement of fungal proteins in the formation of biogenic copper carbonate nanoparticles (CuNPs) using a carbonate-enriched biomass-free ureolytic fungal culture supernatant. Proteomic analysis was conducted that identified the major proteins present in the culture supernatant. Of the proteins identified, triosephosphate isomerase (TPI) exhibited a strong affinity to the CuNPs, and the impact of purified TPI on CuNP formation was studied in detail. The combined use of scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) confirmed that TPI played an important role in controlling the morphology and structure of the nanomaterials. Fourier transform infrared spectroscopy (FTIR) was applied to examine conformational changes of the proteins to further clarity the interaction mechanisms with CuNPs during biomineralization. Such analyses revealed unfolding of proteins on the mineral surface and an increase in β sheets within the protein structure. These results extend understanding of how microbial systems can influence biomineral formation through protein secretion, the mechanisms involved in formation of complex protein/inorganic systems, and provide useful guidelines for the synthesis of inorganic-protein based nanomaterials.

Exploring the interactions between protein coronated CdSe quantum dots and nanoplastics

QDs after protein coronation can undergo sequential interaction with other pollutants which may alter the physiochemical property of the QDs and influence the stability of the corona proteins.

Corn derivative mesoporous carbon microspheres supported hydrophilic polydopamine for development of new membrane: Water treatment containing bovine serum albumin

A new mixed matrix membrane (MMM) was prepared by incorporating biological mesoporous carbon microspheres (mCMSs) from corn starch polysaccharide-supported hydrophilic polydopamine (PDA), as a mesoporous and large-surface area filler, selective modifier, and pore-forming agent, into polyvinylidene fluoride (PVDF) matrix in presence of polyethylene glycol (PEG) as a hydrophilic agent. The structural parameters of the prepared membranes were characterized via FE-SEM, BET/BJH, XRD, FT-IR, and AFM analyses, sorption experiments, water permeability assessments, porosimetry tests, flux recovery ratio (FRR) evaluations, and contact angle measurements, with the so-called central composite design (CCD) been successfully applied for optimization and investigation of the effects of the operational parameters. The results were then applied to treat double-distilled water containing bovine serum albumin (BSA) utilizing a cross-module set-up. Based on the findings, the content of the mCMS-PDA in the PVDF matrix significantly affected the contact angle, pure water flux (PWF), FRR, and BSA removal. In this respect, the PWF of the PVDF-PEG-mCMS-PDA increased from 10.25 to 27.78 L/m² h with increasing the mCMS-PDA content, with the peak FRR (93.84%) of the PVDF-PEG-mCMS-PDA seen at maximum surface hydrophilicity of the membrane.

The molecular insights into protein adsorption on hematite surface disclosed by in-situ ATR-FTIR/2D-COS study

Proteins are of ubiquitous interest in the Life Sciences but are of interest in the Geosciences as well because of the significant role these compounds play in the biogeochemical cycling of trace and nutrient elements. Structural changes resulting from the adsorption of proteins onto mineral surfaces may alter protein biological function and other environmental interactions. Iron oxides are major sinks of a range of environmental elements including organic compounds. In this study, the adsorption of the broadly studied model protein BSA onto the hematite mineral surface was characterized as a function of pH, ionic strength, and BSA concentration using in-situ Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy. BSA lost the α-helix and gain β-sheets in the secondary structure during adsorption on hematite. BSA adsorption was maximum at pH 5, a value close to the BSA isoelectric point (~ pH 5), and lower at pH 4 and pH 7. Increasing ionic strength decreased to total BSA adsorption. Two-dimensional correlation spectroscopy analysis of the ATR-FTIR spectra revealed that higher initial BSA concentration and the consequent higher BSA surface loading enhanced BSA adsorption by protein–protein interaction, which less ordered structures changes into more compact forms decrease, hence compacting the structural arrangement and could promoting multilayers/aggregation formation on the mineral surface. The activity of enzymes following adsorption on mineral surfaces requires further study.

Synthesis and characterization of cellulose/TiO2 nanocomposite: Evaluation of in vitro antibacterial and in silico molecular docking studies

Cellulose/TiO₂ nanocomposite was synthesized using coagulation in sodium hydroxide-thiourea-urea aqueous solution medium by precipitation method. This method was accomplished green and cost-effective for the fabrication of composite nanomaterials. Structure, morphology and optical properties of the nanocomposite were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, and ultraviolet diffuse reflectance spectra respectively. XRD results showed the anatase structure of TiO₂ while FESEM micrograph showed evidence of particle size ranging from 20 to 40 nm for cellulose/TiO₂ nanocomposite. The Fourier transfer infrared spectroscopy investigation reveals that the TiO₂ is bound to hydroxyl groups to the cellulose by hydrogen bonding. The optical energy bandgap is found to be 2.71 eV for nanocomposite from the UV-DRS. The mechanical strength of the composites gently escalated with the addition of TiO₂ nanoparticles into cellulose polymer matrix. Cellulose/TiO₂ nanocomposite was screened for their in vitro antibacterial activity against Staphylococcus aureus and Escherichia coli bacteria have been investigated. Additionally, the results obtained from in silico molecular docking studies confirm the interaction of nanocomposite with proteins, were in good agreement with the experimental data. This finding provides a novel and simple method for the synthesis of cellulose/TiO₂ nanocomposite as functional biomaterials.

Following in Situ the Degradation of Mesoporous Silica in Biorelevant Conditions: At Last, a Good Comprehension of the Structure Influence

Mesoporous silica nanoparticles (MSNs) have seen a fast development as drug delivery carriers thanks to their tunable porosity and high loading capacity. The employ of MSNs in biomedical applications requires a good understanding of their degradation behavior both to control drug release and to assess possible toxicity issues on human health. In this work, we study mesoporous silica degradation in biologically relevant conditions through in situ ellipsometry on model mesoporous nanoparticle or continuous thin films, in buffer solution and in media containing proteins. In order to shed light on the structure/dissolution relationship, we performed dissolution experiments far from soluble silicate species saturation. Via a complete decorrelation of dissolution and diffusion contributions, we proved unambiguously that surface area of silica vectors is the main parameter influencing dissolution kinetics, while thermal treatment and open mesoporous network architecture have a minor impact. As a logical consequence of our dissolution model, we proved that the dissolution lag-time can be promoted by selective blocking of the mesopores that limits the access to the mesoporous internal surface. This study was broadened by studying the impact of the organosilanes in the silica structure, of the presence of residual structuring agents, and of the chemical composition of the dissolution medium. The presence of albumin at blood concentration was found affecting drastically the dissolution kinetics of the mesoporous structure, acting as a diffusion barrier. Globally, we could identify the main factors affecting mesoporous silica materials degradation and proved that we can tune their structure and composition for adjusting dissolution kinetics in order to achieve efficient drug delivery.

Adsorption and fractionation of Pt, Pd and Rh onto inorganic microparticles and the effects of macromolecular organic compounds in seawater

Adsorption and fractionation of Pt, Pd and Rh (defined here as platinum group elements, PGEs) onto the representative inorganic microparticles, including Fe₂O₃, MnO₂, CaCO₃, SiO₂, Al₂O₃ and kaolinite in seawater were investigated. The effects of macromolecular organic compounds (MOCs) as the representatives of organic matter, including humic acids (HA), bovine serum albumin (BSA) and carrageenan, on the adsorption were also studied considering that organic matter is ubiquitous in seawater and indispensable to marine biogeochemical cycles. In the absence of MOCs, the representative mineral particles Fe₂O₃ and MnO₂ had the strongest interaction with PGEs. The adsorption of PGEs onto the representative biogenic particles SiO₂ and CaCO₃ and lithogenic particles Al₂O₃ and kaolinite was similar or weaker than onto the mineral particles. MOCs inhibited the interaction between PGEs and the particles except for Pt and Pd onto the biogenic particles in artificial seawater. This impediment may be closely related to the interaction between particles, MOCs and elements. The partition coefficient (log K_d) of Pt was similar (∼4.0) in the presence of MOCs, indicating that the complexation between Pt and MOCs was less important than hydrolysis or adsorption onto the acid oxide particle surface. Rh tended to fractionate onto the mineral and lithogenic particles in the presence of HA and carrageenan, while Pd was more likely to fractionate onto the biogenic particles. However, BSA enhanced the fractionation tendency of Pd onto the mineral particles. The results indicate that the adsorption behavior of Pd onto inorganic particles was significantly affected by the composition or the type of MOCs. Hence, the interaction between PGEs and inorganic particles may be greatly affected by the macromolecular organic matter in the ocean.

Detection of bovine serum albumin using hybrid TiO2 + graphene oxide based Bio - resistive random access memory device

Bio - molecules detection and their quantification with a high precision is essential in modern era of medical diagnostics. In this context, the memristor device which can change its resistance state is a promising technique to sense the bio - molecules. In this work, detection of the Bovine Serum Albumin (BSA) protein using resistive switching memristors based on TiO2 and TiO2 + graphene oxide (GO) is explored. The sensitivity of BSA detection is found to be 4 mg/mL. Both the devices show an excellent bipolar resistive switching with an on/off ratio of 73 and 100 respectively, which essentially demonstrates that the device with GO, distinguishes the resistance states with a high precision. The enhanced performance in the GO inserted device (~ 650 cycles) is attributed to the prevention of multi-dimensional and random growth of conductive paths.