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Plasma treatment of polymers results in the texturing of their surface in micro/nano range and generates functional surface groups which again facilitates the linker-free (physical and covalent) immobilization of biomolecules.
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Over the last years, polymers have gained great attention as substrate material, because of the possibility to produce low-cost sensors in a high-throughput manner or for rapid prototyping and the wide variety of polymeric materials available with different features (like transparency, flexibility, stretchability, etc.). For almost all biosensing a...
Citations
... Precise oxidation of various materials has attracted the attention of numerous authors involved across multiple research fields, from atomic layer oxidation [1,2] to polymer activation [3][4][5], sterilization [6,7], and degreasing of inorganic materials [8,9]. Oxygen under ambient conditions is composed of two-atom molecules, which are not very chemically reactive at room temperature [10,11]. ...
Calorimetry is a commonly used method in plasma characterization, but the accuracy of the method is tied to the accuracy of the recombination coefficient, which in turn depends on a number of surface effects. Surface effects also govern the kinetics in advanced methods such as atomic layer oxidation of inorganic materials and functionalization of organic materials. The flux of the reactive oxygen atoms for the controlled oxidation of such materials depends on the recombination coefficient of materials placed into the reaction chamber, which in turn depends on the surface morphology, temperature, and pressure in the processing chamber. The recombination coefficient of a well-oxidized cobalt surface was studied systematically in a range of temperatures from 300 to 800 K and pressures from 40 to 200 Pa. The coefficient increased monotonously with decreasing pressure and increasing temperature. The lowest value was about 0.05, and the highest was about 0.30. These values were measured for cobalt foils previously oxidized with oxygen plasma at the temperature of 1300 K. The oxidation caused a rich morphology with an average roughness as deduced from atomic force images of 0.9 µm. The results were compared with literature data, and the discrepancy between results reported by different authors was explained by taking into account the peculiarities of their experimental conditions.
... PoCs, such as microfluidic chips, have become an important diagnostic tool in medicine. Their main advantage is to speed up diagnosis and allow the monitoring of diseases, mainly in non-urban areas or areas with limited access to medicine in LMICs, and are characterized by their low cost and high efficiency (Wieland et al., 2020). Therefore, the objective of this work is designing a method for the detection of IgG and IgM anti-SARS-COV-2 antibodies and implementing it in a microfluidic chip. ...
The outbreak of COVID-19, a disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, is regarded as the most severe of the documented coronavirus pandemics. The measurement and monitoring of SARS-CoV-2 antibody levels by serological tests are relevant for a better epidemiological and clinical understanding of COVID-19. The aim of this work was to design a method called the SARS-CoV-2 antibody detection method (SARS-CoV-2 AbDM) for fluorescence immunodetection of anti-SARS-CoV-2 IgG and IgM on both plate and microfluidic chip. For this purpose, a system with magnetic beads that immobilize the antigen (S protein and RBD) on its surface was used to determine the presence and quantity of antibodies in a sample in a single reaction. The SARS-CoV-2 AbDM led to several advantages in the performance of the tests, such as reduced cost, possibility of performing isolated or multiple samples, potential of multiplex detection, and capacity to detect whole blood samples without losing resolution. In addition, due to the microfluidic chip in conjunction with the motorized actuated platform, the time, sample quantity, and operator intervention during the process were reduced. All these advantages suggest that the SARS-CoV-2 AbDM has the potential to be developed as a PoC that can be used as a tool for seroprevalence monitoring, allowing a better understanding of the epidemiological and clinical characteristics of COVID-19 and contributing to more effective and ethical decision-making in strategies to fight against the COVID-19 pandemic.
... Nitrogen and ammonia, for example, are used to form primary amine groups on polymeric surfaces for covalent biomolecule immobilization. 100,126,[128][129][130] Oxygen gas has been widely used to introduce oxygen-containing groups such as hydroxyl (-OH), carboxyl (-COOH), and carbonyl (-CO-) groups to polymeric surfaces such as PCL, 131,132 polyethylene, 133 and polypropylene. 134 Carbon dioxide is another reactive gas that creates carboxylated functional groups on polymeric surfaces such as polypropylene and polystyrene. ...
Surface biofunctionalization aims to create cell-instructive surfaces that control the behavior of cells and modulate cellular interactions by incorporating cell signaling moieties at the materials–biosystem interface. Despite advances in developing bioinert and biocompatible materials, blood clotting, inflammation, and cell death continue to be observed upon the contact of foreign materials with living tissues leading to the materials' rejection. Specific examples include the application of foreign materials in implantable devices (e.g., bone implants, antimicrobial surfaces, and cardiovascular stents), biosensors, drug delivery, and 3D-bioprinting. Biofunctionalization of materials to date has been predominantly realized using wet chemical approaches. However, the complexity of wet chemistry, toxicity of reactants, waste disposal issues, reaction time, poor reproducibility, and scalability drive a need for a paradigm shift from wet chemical approaches to dry methods of surface biofunctionalization. Plasma-based technologies that enable covalent surface immobilization of biomolecules have emerged as dry, reagent-free, and single-step alternatives for surface biofunctionalization. This review commences by highlighting the need for bioinstructive surfaces and coatings for various biomedical applications such as bone implants, antimicrobial surfaces, biosensors, and 3D-bioprinted structures, followed by a brief review of wet chemical approaches for developing biofunctionalized surfaces and biomimetic devices. We then provide a comprehensive review of the development of plasma-based technologies for biofunctionalization, highlighting the plasma–surface interactions and underpinning mechanisms of biomolecule immobilization.
... Cold plasma treatment is a well-known and widespread technique for increasing the hydrophilicity, wettability, and adhesion characteristics of surfaces with different chemical nature and morphology. Historically, it finds application in textiles [1] where it is used to increase the dyeability of natural and synthetic fabrics, and, more recently, in the biomedical field for the immobilization of active and functional derivatives (such as cyclodextrins, dopamine, and/or antibiotic drugs) onto the uppermost layer of different substrates [2][3][4][5][6][7][8]. ...
To improve the capability of non-woven polypropylene-based fabric (NWF-PP) used for face mask production to retain active biomolecules such as polyphenols, the surface functionalization of NWF-PP–directly cut from face masks–was carried out by employing cold plasma with oxygen. The nature/structure of the functional groups, as well as the degree of functionalization, were evaluated by ATR-FTIR and XPS by varying the experimental conditions (generator power, treatment time, and oxygen flow). The effects of plasma activation on mechanical and morphological characteristics were evaluated by stress–strain measurements and SEM analysis. The ability of functionalized NWF-PP to firmly anchor polyphenols extracted from cloves was estimated by ATR-FTIR analysis, IR imaging, extractions in physiological solution, and OIT analysis (before and after extraction), as well as by SEM analysis. All the results obtained converge in showing that, although the plasma treatment causes changes–not only on the surface–with certain detriment to the mechanical performance of the NWF-PP, the incorporated functionalities are able to retain/anchor the active molecules extracted from the cloves, thus stabilizing the treated surfaces against thermo-oxidation even after prolonged extraction.
... PMMA films can be conveniently processed at a low cost [3]. Its climate-change resistance is higher than that of other polymers [4]. For its characteristics of chemically inert, outstanding mechanical properties such as ease of manufacture rigidity, and low density, PMMA has been widely used in biomedical, optical, and various industrial applications. ...
The objective of this work is samples are treated by the dc plasma system for different gases (oxygen, argon, and nitrogen) that utilizing to modulate (PMMA) polymethyl methacrylate surface and contrast results with untreated samples. UV- Visible Spectroscopy has characterized the optical properties of plasma-treated membranes. Fourier Transformation Infrared Spectroscopy has been characterized by changes in the chemical composition. The results (FTIR) revealed differences in the molecular bond of polymer chains in the polymer membranes’ surface structure. The findings of UV-Visible spectroscopy clearly demonstrate a decrease in the transmission of light due to plasma therapy, as well as imaginary and real portions of the dielectric and refractive constant of the samples various are determined utilizing the absorption, reflection, and transmission spectrum of the samples and determined the energy gap.
... The activation state of polymer surfaces and subsequent protein immobilization was shown to be critically influenced by plasma treatment conditions and parameters such as plasma cycle time, compressed air flow rate, gas composition, substrate temperature, and power density. 38,39 Additionally, we were able to create biomolecule micropatterns with adjustable contrast on COP surfaces by variation of process conditions during plasma activation. 37 Based on that, we chose optimized conditions for polymer plasma activation and kept the settings constant in all experiments. ...
Polymeric materials play an emerging role in biosensing interfaces. Within this regard, polymers can serve as a superior surface for binding and printing of biomolecules. In this study, we characterized 11 different polymer foils [cyclic olefin polymer (COP), cyclic olefin copolymer (COC), polymethylmethacrylate (PMMA), DI-Acetate, Lumirror 4001, Melinex 506, Melinex ST 504, polyamide 6, polyethersulfone, polyether ether ketone, and polyimide] to test for the applicability for surface functionalization, biomolecule micropatterning, and fluorescence microscopy approaches. Pristine polymer foils were characterized via UV-vis spectroscopy. Functional groups were introduced by plasma activation and epoxysilane-coating. Polymer modification was evaluated by water contact angle measurement and X-ray photoelectron spectroscopy. Protein micropatterns were fabricated using microcontact printing. Functionalized substrates were characterized via fluorescence contrast measurements using epifluorescence and total internal reflection fluorescence microscopy. Results showed that all polymer substrates could be chemically modified with epoxide functional groups, as indicated by reduced water contact angles compared to untreated surfaces. However, transmission and refractive index measurements revealed differences in important optical parameters, which was further proved by fluorescence contrast measurements of printed biomolecules. COC, COP, and PMMA were identified as the most promising alternatives to commonly used glass coverslips, which also showed superior applicability in subcellular micropatterning experiments.
... Plasma-activated polymeric surfaces have earned a prominent place within the biomedical field for their ability to immobilize biologically active molecules [76,[137][138][139][140]. In fact, some of the plasma-induced functionalities such as carboxyl, hydroxyl, amine and aldehyde groups were proven to possess a great potential to covalently bind proteins [141,142]. ...
... For instance, it was previously reported that surfaces solely enriched with oxygen-containing functionalities and exhibiting a moderate hydrophilicity are deemed to trigger a more effective protein adsorption compared to surfaces enriched with both nitrogen-and oxygen-containing functionalities and exhibiting a super-hydrophilicity [76]. XPS analyses were therefore frequently conducted to detect the density of grafted functional groups on plasma-activated polymeric surfaces pre-immobilization of proteins [76,137]. Nonetheless, in order to make sure that proteins are successfully bound to such plasma-induced functional molecules, few researchers have again performed XPS measurements post-protein immobilization [67,69,144]. ...
During the last few decades, non-thermal plasma surface functionalization of polymeric materials has increasingly earned a high-flying position in a wide range of application fields. Nonetheless, given the diversity of chemical reactions occurring between the surface and the multitude of active species present in plasma, a chaotic insertion of non-specific surface functional groups might befall. Therefore, achieving controlled surface chemistries can be a challenging approach demanding excessive optimization of the working parameters. In fact, correlations between the used working parameters, the generated plasma active species and the induced surface chemistry should be carefully analyzed for a deeper fundamental understanding of the plasma-surface interactions. To do so, researchers have been employing a broad range of surface analytical techniques with X-ray photoelectron spectroscopy (XPS) being the most widely used since it accurately determines the surface chemical composition at a depth approximately equaling the region depth affected by the plasma activation (a few nanometers). This review paper is therefore dedicated to provide an extensive overview on the different XPS measurement capabilities applied to chemically characterize plasma-activated polymeric surfaces. Beside the typical measurements determining the surface elemental composition, more advanced XPS analyses will be discussed such as peak fitting, XPS mapping, angle resolved XPS, derivatization reactions combined with XPS analyses and SEM-like imaging capabilities of XPS used for 3D scaffolds. Moreover, clear distinctions between post-plasma and exclusive in-plasma surface interactions are also made via a literature overview involving XPS analyses undertaken in situ. Finally, the well-known ageing effect of plasma-activated surfaces is deeply tackled through XPS measurements performed after relatively prolonged storage times. The limitations associated with some of the reported XPS analyses are also comprehensively discussed. An extended knowledge on plasma surface interactions could be as such gained. Overall, this review constitutes a perfect-picture reference for all future studies involving a plasma activation of polymers in particular and XPS analyses in general.
... 149 Despite this, adsorption of biomolecules to a polymeric surface can be enhanced through plasma activation and heating of the polymer substrate near its glass transition temperature, where the protein conjugation is comparable to the attachment achievable using a EDC/NHS linker. 150 Carbodiimide cross-linking is a popular approach to attach proteins onto a surface, one of the most popular carbodiimide compounds being (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide or EDC. EDC specifically functions as an activator for forming an amide bond between carboxylic acids and primary amines, the latter forms the backbone of proteins. ...
Integrated microfluidic biosensors enable powerful microscale analyses in biology, physics, and chemistry. However, conventional methods for fabrication of biosensors are dependent on cleanroom-based approaches requiring facilities that are expensive and are limited in access. This is especially prohibitive toward researchers in low- and middle-income countries. In this topical review, we introduce a selection of state-of-the-art, low-cost prototyping approaches of microfluidics devices and miniature sensor electronics for the fabrication of sensor devices, with focus on electrochemical biosensors. Approaches explored include xurography, cleanroom-free soft lithography, paper analytical devices, screen-printing, inkjet printing, and direct ink writing. Also reviewed are selected surface modification strategies for bio-conjugates, as well as examples of applications of low-cost microfabrication in biosensors. We also highlight several factors for consideration when selecting microfabrication methods appropriate for a project. Finally, we share our outlook on the impact of these low-cost prototyping strategies on research and development. Our goal for this review is to provide a starting point for researchers seeking to explore microfluidics and biosensors with lower entry barriers and smaller starting investment, especially ones from low resource settings.
... Due to the competitive assay format, the signal measured on the receiver area is inverse proportional to the concentration of the analyte. In order to enable POC testing using the OptoAssay, a 3D printed PhotoBox that allows for illumination with red and far-red light has been built (Figure1 D,E) 10 . The illumination can be controlled with a smartphone that is linked via a Bluetooth module to the electronics of the PhotoBox. ...
Circumventing the limitations of current bioassays, we introduce the first light-controlled assay, the OptoAssay, towards wash- and pump-free point-of-care diagnostics. Extending the capabilities of standard bioassays with light-dependent and reversible interaction of optogenetic switches, OptoAssays enable a bi-directional movement of assay components, only by changing the wavelength of light. Combined with smartphones, OptoAssays obviate the need for external flow control systems like pumps or valves and signal readout devices.
... The role of PMMA as a 3D matrix had explored by Arya et al., [18]. However, for this PMMA need to be laser engraved and plasma-treated [19,20] to create functional groups on the surface for the successful immobilization of biomolecules. Nevertheless, after adding CDs to the PMMA solution there is no need for this extra step as CDs possess many functional groups along with a very high surface area that assists in the biomolecule immobilization. ...
... In CD-PMMA composite, PMMA does not have any functional groups to link with the biomolecules [19,52]. To immobilize the biomolecules on the PMMA surface, the plasma treatment was used by which the reactive groups like eCOOH, eNH 2 was created on the polymer surface [19,53]. ...
... In CD-PMMA composite, PMMA does not have any functional groups to link with the biomolecules [19,52]. To immobilize the biomolecules on the PMMA surface, the plasma treatment was used by which the reactive groups like eCOOH, eNH 2 was created on the polymer surface [19,53]. In the present case, the immobilization was easy without plasma treatment as the CDs already possess the eCOOH, eNH 2 , eOH and so on, reactive groups on the surface which helps in the successful immobilization of the antibodies (Fig. 6). ...
TNF-α is a pro-inflammatory cytokine having key roles in cell death, differentiation, survival, proliferation, migration and is a modulator of immune system. Therefore, TNF-α is an ideal biomarker for several disease diagnosis including cancer. However, out of all the biomarkers of cancer, Tumour Necrosis Factor (TNF-α) is less explored for cancer detection. Only a few reports are available of developing biosensors for TNF-α targeting in human serum samples. Also, Carbon Dots (CDs) remains less explored in biosensor application. In this regard, for the first time, a sensitive and low-cost electrochemical biosensor based on CDs has developed. CDs were synthesized by simple yet facile microwave pyrolysis. Poly methyl methacrylate (PMMA) was selected as the matrix to hold CDs to fabricate the biosensing platform. This novel CD-PMMA nanocomposite featuring excellent biocompatibility, exceptional electrocatalytic conductivity, and large surface area. CD-PMMA was applied as transducing material to efficiently conjugate antibodies specific towards TNF-α and fabricate electrochemical immunosensor for specific detection of TNF-α. The fabricated immunosensor was used for the detection of TNF-α within a wide dynamic range of 0.05–160 pg mL⁻¹ with a lower detection limit of 0.05 pg mL⁻¹ and sensitivity of 5.56 pg mL⁻¹ cm⁻². Furthermore, this CD based immunosensor retains high sensitivity, selectivity, and stability. This immunosensor demonstrated a high correlation with the conventional technique, Enzyme-Linked Immunosorbent Assay for early screening of cancer patient serum samples.
