Adsorption study of pellicle proteins to gold, silica and titanium by quartz crystal microbalance method

Titanium particles incorporated polymer monolith microcolumn for phosphoprotein enrichment from biological samples

In proteomic studies, selective enrichment of target phosphoproteins from biological samples is of importance. Of various enrichment methods, affinity chromatography is widely preferred method. Development of micro-affinity columns with simple strategies are in constant demand. Here in this report, for the first time, we have embedded TiO₂ particles within the monolith structure in a single step. Fourier transform infrared spectroscopy and scanning electron microscope analysis has confirmed the successful incorporation of TiO₂ particles within the polymer monolith. Incorporation of 3-(trimethoxy silyl) propyl methacrylate within the poly(hydroxyethyl methacrylate) based monolith composition has enhanced its rigidity and one fold phosphoprotein (α-casein) adsorption capacity. Presence of only 66.6 µg of TiO₂ particles within the monolith has displayed a four-fold higher affinity to α-casein over the non-phosphoprotein i.e. bovine serum albumin. Under optimized conditions (TiO₂ particle and acrylate silane), the affinity monolith has a maximum adsorption capacity of ∼ 72 mg per gram monolith. Translation of TiO₂ particles-monolith into a microcolumn of 3 cm long and 19 µL volume was successful. α-casein was selectively separated from an artificial protein mixture of α-casein and BSA, α-casein spiked human plasma, and cow milk within 7 min.

Multifunctional Titanium Surfaces for Orthopedic Implants: Antimicrobial Activity and Enhanced Osseointegration

The use of implants in orthopedics and dental practice is a widespread surgical procedure to treat diverse diseases. However, peri-implantitis due to infections and/or poor osseointegration can lead to metallic implant failure. The aim of this study was to develop a multifunctional coating on titanium (Ti) surfaces, to simultaneously deal with both issues, by combining antibacterial silver nanoparticles (AgNPs) and regenerative properties of lactoferrin (Lf). A simple and cost-effective methodology that allows the direct multifunctionalization of Ti surfaces was developed. The modified surfaces were characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy, and contact angle measurements. Additionally, in vitro preosteoblast cell adhesion, cell viability, and differentiation were evaluated. The antibacterial capability of the surfaces was tested against Staphylococcus aureus as a prosthesis infection model strain. Our results showed that Lf adsorbed on both Ti surfaces and Ti surfaces with adsorbed AgNPs. Simultaneously, the presence of Lf and AgNPs notably improved preosteoblast adhesion, proliferation, and differentiation, whereas it reduced the bacterial colonization by 97.7%. Our findings indicate that this simple method may have potential applications in medical devices to both improve osseointegration and reduce bacterial infection risk, enhancing successful implantation and patients' quality of life.

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.

Influence of mucin pre-adsorption for lipoteichoic acid adsorption on titanium surfaces

We investigated the adsorption of lipoteichoic acid (LTA) on titanium surfaces by using the quartz crystal microbalance (QCM) method, and confirmed the influence of mucin (MUC) pre-adsorption on LTA adsorption. Two injection methods were evaluated. Namely, Method A: single-step injection of LTA solution to the Ti sensor, and Method B: MUC solution was injected to the Ti sensor followed by LTA injection on the MUC pre-adsorbed surface. QCM measurement revealed that the adsorbed amount of LTA by Method A was low and constant regardless of the increase in LTA concentration. In contrast, the adsorption amount of LTA in Method B increased according with increasing concentration of LTA and was significantly higher than that of Method A. The hydrophobic surface after MUC pre-adsorption was presumed to contribute to the enhancement of LTA adsorption. Our results revealed that MUC pre-adsorption to Ti is necessary for LTA adsorption in living tissue.

Bioadhesion in the oral cavity and approaches for biofilm management by surface modifications

BACKGROUND

All soft and solid surface structures in the oral cavity are covered by the acquired pellicle followed by bacterial colonization. This applies for natural structures as well as for restorative or prosthetic materials; the adherent bacterial biofilm is associated among others with the development of caries, periodontal diseases, peri-implantitis, or denture-associated stomatitis. Accordingly, there is a considerable demand for novel materials and coatings that limit and modulate bacterial attachment and/or propagation of microorganisms.

OBJECTIVES AND FINDINGS

The present paper depicts the current knowledge on the impact of different physicochemical surface characteristics on bioadsorption in the oral cavity. Furthermore, it was carved out which strategies were developed in dental research and general surface science to inhibit bacterial colonization and to delay biofilm formation by low-fouling or "easy-to-clean" surfaces. These include the modulation of physicochemical properties such as periodic topographies, roughness, surface free energy, or hardness. In recent years, a large emphasis was laid on micro- and nanostructured surfaces and on liquid repellent superhydrophic as well as superhydrophilic interfaces. Materials incorporating mobile or bound nanoparticles promoting bacteriostatic or bacteriotoxic properties were also used. Recently, chemically textured interfaces gained increasing interest and could represent promising solutions for innovative antibioadhesion interfaces. Due to the unique conditions in the oral cavity, mainly in vivo or in situ studies were considered in the review.

CONCLUSION

Despite many promising approaches for modulation of biofilm formation in the oral cavity, the ubiquitous phenomenon of bioadsorption and adhesion pellicle formation in the challenging oral milieu masks surface properties and therewith hampers low-fouling strategies.

CLINICAL RELEVANCE

Improved dental materials and surface coatings with easy-to-clean properties have the potential to improve oral health, but extensive and systematic research is required in this field to develop biocompatible and effective substances.

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.

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.

Adsorption Analysis of Lactoferrin to Titanium, Stainless Steel, Zirconia, and Polymethyl Methacrylate Using the Quartz Crystal Microbalance Method

It is postulated that biofilm formation in the oral cavity causes some oral diseases. Lactoferrin is an antibacterial protein in saliva and an important defense factor against biofilm development. We analyzed the adsorbed amount of lactoferrin and the dissociation constant (K(d)) of lactoferrin to the surface of different dental materials using an equilibrium analysis technique in a 27 MHz quartz crystal microbalance (QCM) measurement. Four different materials, titanium (Ti), stainless steel (SUS), zirconia (ZrO2) and polymethyl methacrylate (PMMA), were evaluated. These materials were coated onto QCM sensors and the surfaces characterized by atomic force microscopic observation, measurements of surface roughness, contact angles of water, and zeta potential. QCM measurements revealed that Ti and SUS showed a greater amount of lactoferrin adsorption than ZrO2 and PMMA. Surface roughness and zeta potential influenced the lactoferrin adsorption. On the contrary, the K(d) value analysis indicated that the adsorbed lactoferrin bound less tightly to the Ti and SUS surfaces than to the ZrO2 and PMMA surfaces. The hydrophobic interaction between lactoferrin and ZrO2 and PMMA is presumed to participate in better binding of lactoferrin to ZrO2 and PMMA surfaces. It was revealed that lactoferrin adsorption behavior was influenced by the characteristics of the material surface.