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plasma layer

Low Pressure Plasma Coating Technology is a technology that generates plasma in a low-pressure vacuum environment to activate the surface of the substrate. At the same time, a gas mixture or evaporated liquid monomer is used as the raw material for the coating, which is introduced into the vacuum process chamber, and then adhered to the surface of the substrate and covalently bonded with it in a plasma atmosphere, to form a dense, high-quality coating with a thickness ranging from 10 nanometers to 100 micrometers.

Customers can customize various functionalized coatings such as hydrophobic, hydrophilic, aldehyde, amino and protein coatings. They are widely used in medical consumables, microfluidic chips, electronics and aerospace to enhance product performance and reliability.

Advantages：

Low substrate deformation: Since the pressure inside the plasma chamber is kept below 500mT, the possibility of thermal deformation of the substrate is greatly reduced. A special fixation device prevents deformation of low melting point polymers.

Uniform and thin film thickness: tens to hundreds of nanometers thick

Low fluorescence background: functional groups and substrates can realize covalent binding, no autofluorescence increase

Flexibility in preparation: density and concentration of functional groups can be adjusted according to demand, and surface wettability can be adjusted.

Environmentally friendly and non-polluting: As a vapor phase treatment method, there will be no problem of contamination from liquid phase reaction, and will not contaminate the surface of the substrate to cause false positive phenomenon.

Mass production: Plasma surface treatment has a fast response time and can meet the needs of mass production.

Long statute of limitations: 1~2 years (confirmed according to specific products)

Examples of surface modification functional groups

Epoxy surfaces

Used for covalent coupling of nucleophilic reagents such as amine-, thiol- and hydroxyl-containing molecules.

Epoxides are cyclic ethers with highly strained ternary rings. The epoxide ring reacts readily with nucleophilic reagents such as amines, hydrazines, thiols, hydroxides and carboxyl groups under acidic or basic conditions. Epoxide surfaces have a longer shelf life than NHS esters and 1,4-phenylene isothiocyclic acid esters (PDITC) because they are more sensitive to humidity and are stable at temperatures up to 40 °C.

Surfaces for adsorption of immobilized amines and carboxyl groups

For non-covalent coupling of charged biochemicals through ionic interactions.

Adsorption immobilization is a method of non-covalent coupling on solid carriers by electrostatic (Coulombic and/or van der Waals) interactions, hydrogen bonding and hydrophobic interactions of reactants. The dissociation energy of a typical electrostatic bond is 130 kJ/mol, which is about one third of the average covalent bond strength. To achieve optimal adhesion, the probe buffer and adhesion conditions (ph) must be optimized.

amine surface

Covalent binding to oligonucleotides by UV cross-linking.

PDITC surface

Used for covalent coupling of nucleophilic reagents such as amine-, thiol- and hydroxyl-containing molecules.

PDITC (1,4-phenylenediisothiocyanate) is a homobifunctional cross-linker that immediately reacts with nucleophilic reagents such as amines, hydrazines, thiols and hydroxides to form stable covalent bonds. Upon attachment of biochemical species, the surface must be blocked by a containment buffer containing small molecules that can access all the reactive groups in the 3d matrix.

carboxylated surface

For EDC/NHS-mediated coupling of amine-containing molecules.

The carboxyl group can be activated by EDC (1-ethyl-3-(3-dimethylaminopropyl) carbodiimide) and NHS (N-hydroxysuccinimide) to form highly reactive intermediates. Such intermediates readily react with amino groups of biochemical species, such as amines and hydrazines.

NHS Surfaces

Direct binding to amine-containing molecules.

NHS-esters react immediately with molecules containing amino groups, such as amines and hydrazines, to form covalent bonds. However, due to their high reactivity, NHS-esters are readily hydrolyzed. Therefore, NHS-activated surfaces should be disposed of promptly after opening the sealed bag.

aldehyde surfaces

For covalent coupling of amine-containing molecules.

The aldehyde group binds to amines, hydrazines and aminoalkoxyacetyl molecules. In the intermediate state, the aldehyde forms an amine group (Schiff group) with the amine. To increase the bond strength, the amine can also be reduced with sodium borohydride or TCEP (Tris (2-carboxyethyl) phosphine) to form a stable amine.

thiol surface

For the covalent coupling of thiol-containing biomolecules and the reaction of thiol-alkenes with olefins.

Maleimide surface

For direct binding of thiol-containing molecules.

Maleimide esters react immediately with thiol groups in biochemical species. Thiol groups can be naturally present in (biological) molecules, e.g. through the amino acid cysteine in proteins, by reductive cleavage of disulfide bonds with reducing agents such as dithiothreitol (DTT, Cleland's reagent), or they can be selectively introduced, e.g. as amine-containing molecules in the case of 2-iminothioughene (Traut's reagent).

Streptavidin and Neutral Trichothecene Surface

For non-covalent, directed coupling of biotin-modified species.

Streptavidin and neutral trichothecenes are tetrameric proteins that can bind four biotin molecules (vitamin B7) or any other biotin-coupled species with very high specificity. The streptavidin/neutral trichothecene-biotin bond is one of the strongest non-covalent bonds known in biochemistry, with a dissociation constant of KD = 10^-15 mol/L. For this reason, it is often used in bioanalytical applications.

Top Asahi Micro offers customized surface modification services for various substrates (e.g. glass, polymers, etc.), please feel free to contact us.

About Us

DingXu (Suzhou) Microfluidics Technology Co., Ltd. is a high-tech enterprise dedicated to the field of microfluidics. We are committed to providing customers with comprehensive microfluidic solutions, including customized microfluidic chip development, surface modification, microfluidic chip processing equipment, and microfluidic instruments. Our team boasts extensive experience and technical expertise, continuously combining professional knowledge with innovative thinking to deliver high-quality solutions. We consistently prioritize customer-centric values, embrace self-challenges, and pursue excellence. Through professionalism, innovation, and collaboration, we aim to create greater value for our customers and contribute to a brighter future in the field of microfluidics.

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