BackgroundProtein–graphene interactions have the potential to play a pivotal role in the future directions of nanomedicine. These interactions lead to diverse processes such as generation of protein coronas, nano–bio interfaces, particle wrapping, and biocatalytic processes that could determine the ultimate fate of graphene nanocomposites in biologic systems. However, such interactions and their effects on the bioavailability of graphene have not yet been widely appreciated, despite the fact that this is the primary surface in contact with cells.MethodsThis paper reports on the integrative physiochemical interaction between trypsin and graphene quantum dots (GQDs) to determine their potential biologic identity in enzyme engineering. This interaction was measured by a wide range of analytical methods.ResultsDefinitive binding and modulation of trypsin–GQDs was demonstrated for the first time by use of vibrational spectroscopy and wetting transparency, which revealed that trypsin was absorbed on GQDs’ surface through its cationic and hydrophilic residues. Our findings suggested that trypsin’s active sites were stabilized and protected by the GQDs, which were likely to be responsible for the high bioavailability of GQDs in enzymes.ConclusionOur work demonstrates the efficacy of GQDs as an enzyme modulator with high specificity, and their great application potential in enzyme engineering as well as enzyme-based therapies.

Pore geometry (pore size and pore interconnectivity) and stiffness are important design requirements for 3D-scaffold fabrication. The required pore geometry allows the passage of growth factors for cell proliferation and removal of waste products, whereas the stiffness influences attachment of osteogenic cells. This work fabricates a 3D scaffold from collagen (Col) and snail shell hydroxyapatite (HApS) and examines the influence of the HApS on the scaffold pore geometry and stiffness. The scaffolds were fabricated using freeze-drying method. Col alone and Col-commercial hydroxyapatite (Col-HApC) scaffolds were used as controls. Scanning electron microscope (SEM) reveals well-interconnected pores for Col-HApS with a mean pore size of 246.9 ± 68.7 μm, which was statistically (p < 0.05) same as that of Col scaffolds 224.4 ± 85.7 μm and different (p < 0.05) from Col-HApC scaffolds 125.5 ± 26.7 μm. Mechanical testing showed a stiffness of 20.8 ± 0.4 kPa, 181.2 ± 11.8 kPa, and 206.9 ± 14.1 kPa for Col, Col-HApC, and Col-HApS, respectively. Uniquely, X-ray diffractometry (XRD) and Infrared (IR) spectroscopy of Col-HApS revealed phases and functional groups that were comparable to graphitic-like carbon nitride (g-C 3 N 4) polymeric structure. It was found that the structural change was responsible for the well-interconnected large pores and high stiffness of the scaffold. It is expected that the effect brings a wide range of functions (such as better cell attachment and nutrient transport) in the scaffold for osteogenesis. The findings indicate that Col-HApS scaffolds would promote osteogenic cell response more usefully than Col-HApC or Col scaffolds.