Biosensing Applications of Graphene Amination by Antibodies toward Grafting

Maxim Basedina^*
*Correspondence: Maxim Basedina, Department of Physics, Alferov University, 8/3 Khlopina Street, Saint Petersburg 194021, Russia, Email:

Keywords

2D materials • Aminated graphene • Graphene modification • Grafting • Antibodies • Photoelectron spectroscopy • Biosensors

Introduction

One of the most important trends in nanomaterial science over the past ten years has been derivatization of two-dimensional crystals. This technique is a powerful tool for engineering the physics of crystals and has made remarkable progress in the practical applications of these materials. Inferable from its flexible science and simplicity of enormous scope combination, graphene has turned into the most prestigious 2D precious stone in the field of derivatization with the presence of a huge group of synthetically changed graphenes upon its covalent uniting by a different arrangement of useful gatherings. Chemical derivatization enables us to adjust the wettability of graphene layers by a variety of solvents and their dispersibility in polymer matrixes, as well as the covalent immobilization of a variety of biomolecules, in addition to advancing the development of nextgeneration graphene-based sensing systems, optoelectronic devices, and metalfree catalysts by synthesizing CMGs with the desired band structure, charge transport and electron field emission properties, optical Particularly relevant to CMG biosensing applications is the latter feature. Graphene films are useful in the production of transducers for chemiresistive sensing platforms due to their excellent surface-to-volume ratio, excellent sensitivity of the electronic structure to the appearance of any molecule, low intrinsic electrical noise, and contact resistance. Another powerful method for creating highly selective sensing devices is to take advantage of the surface plasmon resonance effects that are present in graphene derivatives [1,2].

However, the primary disadvantage is that there is no selectivity in chemiresistive response to any analyte, negating all of graphene's advantages. Biorecognizing molecules, such as DNA strands, aptamers, or antibodies, can be introduced to the surface of graphene to solve this problem and give it the desired selectivity. Here, the ease of functionalization shines through, enabling us to anchor biomolecules through covalent bonding rather than relying on biomolecules' unstable non-covalent grafting through their Van-der-Waals interaction with the graphene layer. This offers the lower corruption of a sensor during its utilization and upgrades its responsiveness because of a higher effect of the charge move from the biorecognizing agent.

Literature Review

Up to this point, numerous biosensing devices based on CMGs have been developed and tested, demonstrating the value of employing CMGs. The covalent immobilization of DNA molecules and aptamers through covalent bonding with the hydroxyl and carboxyl groups that are present in these CMGs has primarily been tested for this purpose with partially reduced Graphene Oxide (GO) and Carboxylated (C-xy) graphene layers. In turn, applications of aminated graphene are uncommon and mostly restricted by the fact that graphene layers are modified by aliphatic linkers with the amine groups rather than directly by amines, which makes it difficult to use the graphene layer as a transducer. Using amine groups for covalent immobilization through carbo-amide bonding with biorecognizing molecule carboxyl fragments would also expand the library of graphene-based biosensing devices, facilitating their performance and broadening the detection range of the target analytes. Through reductive amination and subsequent covalent grafting by monoclonal antibodies against IgM immunoglobulins, we consider a simple method for the conversion of GO into aminated graphene. We describe the biosensing capabilities of aminated graphene with immobilized antibodies as well as the acquired materials' chemistry, morphology, and electronic structure [3,4].

Discussion

Using a modified Leucart reaction, the initial GO was liquid-phase reductively aminated to produce aminited graphene. Briefly, 150 mL of CH3NO was added to 200 mL of aqueous suspension containing 1% GO in a Teflon reaction vessel. The acquired reaction mixture was heated to T=165℃ for an additional 48 hours while being stirred with a 250 rpm mixer. Using a glass filter with a pore size of 40 m, the synthesized rGO-Am was thoroughly washed with deionized water (3 cycles) and isopropyl alcohol to produce the rGO-Am powder after the suspension was cooled to room temperature. The fabricated rGO-Am powder was further dispensed in isopropyl alcohol, achieving a concentration of 0.1 mg/mL with the subsequent deposition by the spray-coating technique, in order to fabricate the rGO-Am films on the desired wafer and TEM grids for the subsequent examination by spectroscopic and microscopic techniques prior to and after immobilization of the antibodies. Drop-casting the GO aqueous suspension at a concentration of 0.01 weight percent onto the Si wafers produced the flawless rGO films. The formed films were then annealed at T=650°C in an ultra-high vacuum chamber (P=109 Torr) for 3 hours: 1.5 hours to reach the indicated temperature, which was maintained for 1.5 hours. These were then dried overnight at room temperature (T=25℃) [5,6].

Conclusion

The science of the concentrated on materials was inspected through a bunch of center level strategies and spectroscopic techniques, specifically XPS, XAS and Fourier change infrared (FTIR) spectroscopy. Using an Infralum-08 spectrometer (InfraLUM, St. Petersburg, Russia) in the attenuated total reflectance (ATR) mode, FTIR spectra of the investigated CMGs were obtained from films on the Si wafers that were between 1 and 2 m thick. For the purpose of obtaining FTIR spectra of IgM antibodies, 10 milliliters of the appropriate solution at a concentration of 0.1 mg/mL were dropped directly onto the crystal of the spectrometer, and measurements were carried out prior to the solution drying off.

At Helmholtz-Zentrum Berlin (HZB), the ultra-high vacuum experimental station of the Russian-German beam line of the electron storage ring BESSY-II collected X-ray photoelectron and X-ray absorption spectra. On the Si wafers, 50–100 nm thick films were used for the measurements. All of the samples were evacuated for 24 hours without heating prior to the measurements to a pressure of P10-9 Torr, which was still sufficient to remove all adsorbates while maintaining the chemistry of the materials. To think about spatial heterogeneity, the spectra were gathered from four equidistant spots of the example with a size of ca. 200 × 100 μm. The contrast between the acquired spectra was under 3%, checking the consistency of the relative multitude of tests, especially the ones with the immobilized antibodies. The averaged spectra were used in subsequent processing.

With an excitation energy of 850 eV and an energy step of 0.5 eV for the survey spectra and 0.05 eV for the C 1s and N 1s spectra, the X-ray photoelectron spectra were measured. The C K and N K X-ray absorption spectra were acquired in the total electron yield mode by recording the sample drain current while varying the photon energy in the range of hv=280–315 eV for the former and hv=395-420 eV for the latter. The collected X-ray photoelectron spectra were calibrated in accordance with the position of the reference Au 4f7/2 line at 84.0 eV. For the XAS measurements, the "magic" angle of=54.7° was chosen to provide nearly equal excitation of - and -related states.

Acknowledgement

None.

Conflict of Interest

There are no conflicts of interest by author.

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