Protein adsorption characterization

Peptide-based self-assembled monolayers (SAMs): what peptides can do for SAMs and vice versa

Self-assembled monolayers (SAMs) represent highly ordered molecular materials with versatile biochemical features and multidisciplinary applications. Research on SAMs has made much progress since the early begginings of Au substrates and alkanethiols, and numerous examples of peptide-displaying SAMs can be found in the literature. Peptides, presenting increasing structural complexity, stimuli-responsiveness, and biological relevance, represent versatile functional components in SAMs-based platforms. This review examines the major findings and progress made on the use of peptide building blocks displayed as part of SAMs with specific functions, such as selective cell adhesion, migration and differentiation, biomolecular binding, advanced biosensing, molecular electronics, antimicrobial, osteointegrative and antifouling surfaces, among others. Peptide selection and design, functionalisation strategies, as well as structural and functional characteristics from selected examples are discussed. Additionally, advanced fabrication methods for dynamic peptide spatiotemporal presentation are presented, as well as a number of characterisation techniques. All together, these features and approaches enable the preparation and use of increasingly complex peptide-based SAMs to mimic and study biological processes, and provide convergent platforms for high throughput screening discovery and validation of promising therapeutics and technologies.

Relationship and improvement strategies between drug nanocarrier characteristics and hemocompatibility: What can we learn from the literature

This article discusses the various blood interactions that may occur with various types of nano drug-loading systems. Nanoparticles enter the blood circulation as foreign objects. On the one hand, they may cause a series of inflammatory reactions and immune reactions, resulting in the rapid elimination of immune cells and the reticuloendothelial system, affecting their durability in the blood circulation. On the other hand, the premise of the drug-carrying system to play a therapeutic role depends on whether they cause coagulation and platelet activation, the absence of hemolysis and the elimination of immune cells. For different forms of nano drug-carrying systems, we can find the characteristics, elements and coping strategies of adverse blood reactions that we can find in previous researches. These adverse reactions may include destruction of blood cells, abnormal coagulation system, abnormal effects of plasma proteins, abnormal blood cell behavior, adverse immune and inflammatory reactions, and excessive vascular stimulation. In order to provide help for future research and formulation work on the blood compatibility of nano drug carriers.

Titanium and Protein Adsorption: An Overview of Mechanisms and Effects of Surface Features

Titanium and its alloys, specially Ti6Al4V, are among the most employed materials in orthopedic and dental implants. Cells response and osseointegration of implant devices are strongly dependent on the body-biomaterial interface zone. This interface is mainly defined by proteins: They adsorb immediately after implantation from blood and biological fluids, forming a layer on implant surfaces. Therefore, it is of utmost importance to understand which features of biomaterials surfaces influence formation of the protein layer and how to guide it. In this paper, relevant literature of the last 15 years about protein adsorption on titanium-based materials is reviewed. How the surface characteristics affect protein adsorption is investigated, aiming to provide an as comprehensive a picture as possible of adsorption mechanisms and type of chemical bonding with the surface, as well as of the characterization techniques effectively applied to model and real implant surfaces. Surface free energy, charge, microroughness, and hydroxylation degree have been found to be the main surface parameters to affect the amount of adsorbed proteins. On the other hand, the conformation of adsorbed proteins is mainly dictated by the protein structure, surface topography at the nano-scale, and exposed functional groups. Protein adsorption on titanium surfaces still needs further clarification, in particular concerning adsorption from complex protein solutions. In addition, characterization techniques to investigate and compare the different aspects of protein adsorption on different surfaces (in terms of roughness and chemistry) shall be developed.

Adsorption behaviors of salivary pellicle proteins onto denture base metals using 27-MHz quartz crystal microbalance

BACKGROUND

The adsorption of salivary pellicle proteins onto the material surface is key for denture plaque formation.

OBJECTIVE

We aimed to investigate the adsorption of bovine serum albumin (BSA) and mucin (MCN) onto denture base metal materials using a 27-MHz quartz crystal microbalance (QCM) method.

METHODS

A gold (Au), titanium (Ti), and cobalt chromium alloy (Co-Cr) sensors were employed for QCM measurements. Adsorbed amounts of BSA or MCN were calculated by observing the frequency decrease, and the apparent reaction rate, kobs, was obtained by the curve fitting of the frequency shift against the adsorption time.

RESULTS

The adsorbed amounts of BSA on Ti were significantly lower than those on Au and Co-Cr. For MCN adsorption, Au showed significantly greater amounts of adsorption than Co-Cr. The kobs of Ti for BSA adsorption was significantly smaller than for the Co-Cr. The kobs of Ti, and Co-Cr for MCN adsorption were significantly smaller than for the Au. A clear correlation was not determined between adsorbed amounts of BSA or MCN onto each sensor and the surface topography or contact angles.

CONCLUSIONS

The difference of denture base metals and the difference of salivary proteins influences the adsorption behavior of salivary proteins.

Evaluation of protein adsorption to diamond-like carbon (DLC) and fluorinedoped DLC films using the quartz crystal microbalance method

The aim of the present study was to evaluate albumin adsorption to stainless steel (SUS), diamond-like carbon (DLC) and fluorinedoped DLC (F-DLC) films using the quartz crystal microbalance (QCM) method. Each sensor was characterized using atomic force microscopy, surface roughness and surface wettability measurements and surface free energy calculations. Adsorbed amounts of bovine serum albumin on DLC and F-DLC were significantly lower than that on SUS (p<0.05). The apparent first-order reaction rate, k_obs, of F-DLC was significantly larger than those of SUS and DLC (p<0.05). Moreover, significantly lower total surface free energies of DLC and F-DLC influenced the albumin absorbed amounts and k_obs. Furthermore, a clear correlation was found between the albumin absorbed amounts and the hydrogen bond component of the total surface free energy. Thus, DLC or F-DLC coating is effective for preventing protein adsorption on orthodontic appliances.

Biocompatibility of polymer-based biomaterials and medical devices – regulations,in vitroscreening and risk-management

Biomaterials play an increasing role in modern health care systems.

Ubiquitin immobilized on mesoporous MCM41 silica surfaces - Analysis by solid-state NMR with biophysical and surface characterization

Deriving the conformation of adsorbed proteins is important in the assessment of their functional activity when immobilized. This has particularly important bearings on the design of contemporary and new encapsulated enzyme-based drugs, biosensors, and other bioanalytical devices. Solid-state nuclear magnetic resonance (NMR) measurements can expand our molecular view of proteins in this state and of the molecular interactions governing protein immobilization on popular biocompatible surfaces such as silica. Here, the authors study the immobilization of ubiquitin on the mesoporous silica MCM41 by NMR and other techniques. Protein molecules are shown to bind efficiently at pH 5 through electrostatic interactions to individual MCM41 particles, causing their agglutination. The strong attraction of ubiquitin to MCM41 surface is given molecular context through evidence of proximity of basic, carbonyl and polar groups on the protein to groups on the silica surface using NMR measurements. The immobilized protein exhibits broad peaks in two-dimensional 13C dipolar-assisted rotational resonance spectra, an indication of structural multiplicity. At the same time, cross-peaks related to Tyr and Phe sidechains are missing due to motional averaging. Overall, the favorable adsorption of ubiquitin to MCM41 is accompanied by conformational heterogeneity and by a major loss of motional degrees of freedom as inferred from the marked entropy decrease. Nevertheless, local motions of the aromatic rings are retained in the immobilized state.

Protein Adsorption to Titanium and Zirconia Using a Quartz Crystal Microbalance Method

Protein adsorption onto titanium (Ti) or zirconia (ZrO₂) was evaluated using a 27 MHz quartz crystal microbalance (QCM). As proteins, fibronectin (Fn), a cell adhesive protein, and albumin (Alb), a cell adhesion-inhibiting protein, were evaluated. The Ti and ZrO₂ sensors for QCM were characterized by atomic force microscopy and electron probe microanalysis observation, measurement of contact angle against water, and surface roughness. The amounts of Fn and Alb adsorbed onto the Ti and ZrO₂ sensors and apparent reaction rate were obtained using QCM measurements. Ti sensor showed greater adsorption of Fn and Alb than the ZrO₂ sensor. In addition, amount of Fn adsorbed onto the Ti or ZrO₂ sensors was higher than that of Alb. The surface roughness and hydrophilicity of Ti or ZrO₂ may influence the adsorption of Fn or Alb. With regard to the adsorption rate, Alb adsorbed more rapidly than Fn onto Ti. Comparing Ti and ZrO₂, Alb adsorption rate to Ti was faster than that to ZrO₂. Fn adsorption will be effective for cell activities, but Alb adsorption will not. QCM method could simulate in vivo Fn and Alb adsorption to Ti or ZrO₂.