Interactions between biomolecules and between substrates and biomolecules is a crucial issue in physics and applications to topics such as biotechnology and organic electronics. The efficiency of bio- and mechanical sensors, of organic electronics systems, and of a number of other devices critically depends on how molecules are deposited on a surface so that these acquire specific functions. Here, we tackle this vast problem by developing a coarse grained model of biomolecules having a recognition function, such as antibodies, capable to quantitatively describe in a simple manner essential phenomena: antigen—antibody and antibody substrate interactions.
The model is experimentally tested to reproduce the results of a benchmark case, such as 1 gold surface functionalization with antibodies and 2 antibody—antigen immune-recognition function. The agreement between experiments and model prediction is excellent, thus unveiling the mechanism for antibody immobilization onto metals at the nanoscale in various functionalization schemes.
These results shed light on the geometrical packing properties of the deposited molecules, and may open the way to a novel coarse-grained based approach to describe other processes where molecular packing is a key issue with applications in a huge number of fields from nano- to biosciences. Interfaces 8 33 View Author Information. Cite this: ACS Appl. Article Views Altmetric -. Citations 2. Cited By.
This article is cited by 2 publications. Derek B. Bush, Thomas A. Surface roughness and contact angle of pristine polymeric biomaterials, and after laser surface texturing experiments. The chemical modification after laser treatment depended on the assist gas used in the process i.
Laser-Materials Interactions | Surface Dynamics Lab | Washington State University
Under neutral conditions, loss of polymer aromaticity and scission of carbonyl groups took place. Furthermore, the polar component of the work of adhesion increased after laser treatment. In this case, an increase of the wettability is observed see Table 3. This was attributed to the increase in roughness, and oxygen containing groups formed on the treated surfaces. More recently, other laser wavelengths were studied with the aim to evaluate their effect on the surface modification of PEEK [ 44 , 47 , 48 ]. Riveiro et al. In order to enhance its adhesion properties, an increase on the wettability was sought.
PEEK was observed to respond very differently as a function of the laser radiation see Figure 7. The 1, m laser radiation burned the surface, while the nm laser radiation was able to ablate the material. This fact can be potentially beneficial to promote cell adhesion onto laser treated PEEK. In this case, the surface energy was increased from Chemical analyses suggested that an increase in hydroxyl and carboxylic groups, along with a decrease on the original carbonyl groups, took place after laser treatment.
It was showed the formation of functional polar groups on laser-treated PEEK surfaces. Figure 7. Adapted from [ 44 ] with permission from Elsevier. These studies only assessed the biocompatibility of laser treated surfaces in terms of the wettability; however, this does not guarantee the biocompatibility of the surfaces, and biological tests in vitro and also in vivo tests are required. The enhancement of biocompatibility of the laser textured PEEK surfaces attributed to the formation of polar groups was confirmed by Zheng et al.
MC3T3-E1 pre-osteoblast were the cells employed in this study. Cell adhesion and proliferation were increased after laser treatment, in conjunction with an increase in the formation of carboxylic groups on the surface. Therefore, it was established the direct relationship between the roughness and the formation of polar groups with the increased biocompatibility of laser-treated PEEK surfaces [ 47 ]. Guo et al. Femtosecond laser irradiation was used to modify the surface of PEEK implants with and without the reinforcement of nano-SiO 2 particles.
A similar result was found by Briski et al. Enhanced fusion and higher deposition of mineralized matrix was observed after 6 months of implantation. Cordero et al. Patterns were produced with UV light from an ArF laser using a mask projection unit. The increased cell growth along preferential directions is proposed to act as a bridge for the bone regeneration in disrupted areas. Bremus-Koebberling et al. In this case, the main aim was their utilization for neuronal repair applications.
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It was demonstrated that not only the pattern periodicity i. These results demonstrate that nano-topography is relevant for the control of the cellular response.
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They also open the door for the application of laser-textured patterns not only for bone tissue engineering, but also for other biomedical applications. Ultra-high-molecular-weight polyethylene UHMWPE is a thermoplastic synthetized from monomers of ethylene - CH 2 n - , used as a bearing material in joint replacement implants for decades. It is commonly used in biomedical applications such as in patella or hip prostheses [ 51 , 55 ].
This is principally due to its high wear and impact resistance, chemical stability, and non-toxicity in contact with corporal fluids. However, the large chemical stability, and low wettability see Table 3 make this material also bioinert. Laser treatments produces the increment of the roughness and wettability see Table 3. However, by subjecting this thermoplastic to ps laser surface radiation from the iodine PALS -Prague Asterix Laser System- laser , different results were revealed [ 89 ].
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In this case, nm laser pulses, with a high energy up to J and a short pulse length ps were used. The chemical analyses of the irradiated surface confirmed substantial changes in the ablated crater composition when compared to the pristine UHMWPE substrate. The results from the mass quadrupole spectrometer MQS showed that C-H, and C-C chemical bonds were broken given the high deposited energy during the ablation process. Also, Raman spectroscopy and infrared absorption analyses demonstrated the enrichment in carbon content of the laser affected areas.
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Lorusso et al. They found a decrease of the WCA with the number of pulses irrespectively of the laser wavelength.
This reduction is more marked for surfaces treated with UV laser radiation. These results are explained in terms of the interaction mechanisms with the substrate. IR and visible laser pulses induces photothermal effects, while UV radiation is able to produce photochemical effects. It is postulated that they modify the surface chemistry. Velardi et al. A similar decrease in the WCA, and the increment of the average roughness with the number of pulses was also observed.
Then, the increment of the wettability is mainly ascribed to the modification of the surface chemistry. In this work, a carbon coating was applied on the surface of the UHMWPE samples to reduce the large transparency exhibited by this material to these laser wavelengths.
The visible and UV laser wavelengths were found the most suitable to tailor the topography, and wettability. Nevertheless, due to the melting of the surface after the laser treatment, some carbon particles were trapped during the process Figure 8 ; however, they are not considered a risk because it is reported that carbon particles do not elicit a toxic response on tissues or heavy inflammatory reactions.
Ganeev, Rashid A.
A large amount of microcracks in the surface of the 1, nm laser treated area was observed. Their formation was attributed to the larger thermal effects which causes thermal stresses produced by this radiation. Although cell viability tests were not performed in this study, the values of roughness obtained through the treatment, and the formation of polar carbon clusters suggested to be beneficial for biological compatibility purposes [ 90 , 91 ]. Figure 8. Adapted from [ 55 ] with permission from Elsevier.
Polypropylene is a biocompatible thermoplastic polymer showing good biostability, good thermal stability, and appropriate mechanical properties [ 92 ]; however, PP exhibits low surface energy see Table 3 , which hinders its systematic use for tissue replacement. Several techniques were studied to increase the low interface energy, such as the deposition of coatings [ 93 ], plasma treatment [ 94 , 95 ], graft polymerization [ 96 ], and injection molding [ 97 ].
Laser - Surface Interactions
Nevertheless, a precise control in the process, and subsequent surface modification remained as a major challenge. Belaud et al. A further insight into the effect of laser textured PP surfaces on their potential applicability in biological applications was provided by Riveiro et al.
The effect of treatment under 1,, , and nm laser wavelengths on the surface features of PP was evaluated. A layer of carbon black was used to increase the original absorption features of this thermoplastic given its high transmittance for wavelengths ranging between and 1, nm [ 99 ]. The treated surfaces were characterized in terms of surface roughness R a , WCA, microhardness, and chemical composition in the treated surfaces.
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