基礎講座 電気泳動(Electrophoresis)

PDMS with designer functionalities—Properties, modifications strategies, and applications

Cellulose nanocrystals: Pretreatments, preparation strategies, and surface functionalization.

Hematology/Oncology Clinics of North America

Over millions of years, animals and plants have evolved complex molecules and structures that endow them with vibrant colors. Among the sources of natural coloration, structural color is prominent in insects, bird feathers, snake skin, plants, and other organisms, where the color arises from the interaction of light with nanoscale features rather than absorption from a pigment. Cellulose nanocrystals (CNCs) are a biorenewable resource that spontaneously organize into chiral nematic liquid crystals having a hierarchical structure that resembles the Bouligand structure of arthropod shells. The periodic, chiral nematic organization of CNC films leads them to diffract light, making them appear iridescent. Over the past two decades, there have been many advances to develop the photonic properties of CNCs for applications ranging from cosmetics to sensors. Here, the origin of color in CNCs, the control of photonic properties of CNC films, the development of new composite materials of CNCs that can yield flexible photonic structures, and the future challenges in this field are discussed. In particular, recent efforts to make flexible photonic materials using CNCs are highlighted.

Understanding the Self-Assembly of Cellulose Nanocrystals-Toward Chiral Photonic Materials.

The ability to tune the interfacial and functional properties of cellulose nanomaterials has been identified as a critical step for the full utilization of nanocellulose in the development of new materials. Here, we use triazine chemistry in a modular approach to install various functionalities and chemistries onto cellulose fibers and cellulose nanocrystals (CNCs). The surface modification is demonstrated in aqueous and organic media. Octadecyl, monoallyl-PEG, benzyl, and propargyl triazinyl derivatives were grafted onto cellulose/CNCs via aromatic nucleophilic substitution in the presence of base as hydrochloric acid scavenger. The covalent nature and degree of substitution of grafted aliphatic, polymeric, alkyne chains, and aromatic rings were characterized through Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, elemental analysis, and thermogravimetric analysis. In addition, AFM and DLS analysis showed minimal change in the geometry and individualized character of CNCs after...

Versatile Surface Modification of Cellulose Fibers and Cellulose Nanocrystals through Modular Triazinyl Chemistry

Poly(dimethylsiloxane) (PDMS) has become the material of choice for fabricating microfluidic channels for lab-on-a-chip applications. Key challenges that limit the use of PDMS in microfluidic applications are its hydrophobic nature, and the difficulty in obtaining stable surface modifications. Although a number of approaches exist to render PDMS hydrophilic, they suffer from reversion to hydrophobicity and, frequently, surface cracking or roughening. In this study, we describe a one-step in-mould method for the chemical modification of PDMS surfaces, and its use to assess the ability of different surfactants to render PDMS surfaces hydrophilic. Thin films of ionic and non-ionic surfactants were patterned into an array format, transferred onto silicone pre-polymer, and subsequently immobilized onto the PDMS surface during vulcanization. The hydrophilicity of the resulting surfaces was assessed by contact angle measurements. The wettability was observed to be dependent on the chemical structure of the surfactants, their concentration and interactions with PDMS. The morphology of modified PDMS surfaces and their change after wetting and drying cycles were visualized using atomic force microscopy. Our results show that while all surfactants tested can render PDMS surfaces hydrophilic through the in-mould modification, only those modified with PEG-PDMS-PEG copolymer surfactants were stable over wetting/dying cycles and heat treatments. Finally, the in-mould functionalization approach was used to fabricate self-driven microfluidic devices that exhibited steady flow rates, which could be tuned by the device geometry. It is anticipated that the in-mould method can be applied to a range of surface modifications for applications in analytical separations, biosensing, cell isolation and small molecule discovery.

/pdf/one-step-in-mould-modification-of-pdms-surfaces-and-its-30h8v6ge68.pdf

One-step in-mould modification of PDMS surfaces and its application in the fabrication of self-driven microfluidic channels

Controlling silicone networks using dithioacetal crosslinks

We report the biophysical characterization of hair from a patient with a de novo ribosomopathy. The patient was diagnosed with a mutation on gene RPS23, which codes for a protein which comprises part of the 40S subunit of the ribosome. The patient presents with a number of phenotypes, including hypotonia, autism, extra teeth, elastic skin, and thin/brittle hair. We combined optical microscopy, tensile tests, and X-ray diffraction experiments on hair samples obtained from the scalp of the patient to a multi-scale characterization of the hair from macroscopic to molecular length scales and observe distinct differences in the biophysical properties in the patient's hair when compared to hair from other family members. While no differences were observed in the coiled-coil structure of the keratin proteins or the structure of the intermediate filaments, the patient's hair was 22% thinner, while the Young's modulus remained roughly constant. The X-ray diffraction results give evidence that the amount of lipids in the cell membrane complex is reduced by 20%, which well accounts for the other observations. The pathologies characterized by these techniques may be used to inform the diagnosis of similar de novo mutations in the future.

/pdf/structural-abnormalities-in-the-hair-of-a-patient-with-a-49vsfqnbag.pdf

Structural Abnormalities in the Hair of a Patient with a Novel Ribosomopathy.

In nature, cells exist in three-dimensional (3D) microenvironments with topography, stiffness, surface chemistry, and biological factors that strongly dictate their phenotype and behavior. The cell...

Ayodele Fatona

Papers

Versatile Surface Modification of Cellulose Fibers and Cellulose Nanocrystals through Modular Triazinyl Chemistry

One-step in-mould modification of PDMS surfaces and its application in the fabrication of self-driven microfluidic channels

Controlling silicone networks using dithioacetal crosslinks

Structural Abnormalities in the Hair of a Patient with a Novel Ribosomopathy.

Tuning the Nanotopography and Chemical Functionality of 3D Printed Scaffolds through Cellulose Nanocrystal Coatings