The (13)C amide I band is still sensitive to conformation change when the regular amide I band cannot be distinguished at the typical position in H2O

Functionalized magnetic lipase/Cu3(PO4)2 hybrid nanoflower: Synthesis, characterization, and enzymatic evaluation

This paper reports the synthesis of magnetic lipase/Cu3(PO4)2 hybrid nanoflowers via a rapid ultrasonication method. The enzyme immobilization and nanoflower growth mechanism can be described as the (a) Fe2+, Cu2+, and phosphate "binding", (b) metal phosphate crystals formation, (c) formation and growth of metal phosphate crystals to form plate-like structures, and (d) self-assembly of plate structures that forms a flower-like structure. Some factors contributing to the morphology of the hybrid nanoflowers structure includes the time and concentration of lipase were studied. The effect of temperature, pH, and duration on the enzyme immobilization yield were also studied. In addition, the strong magnetic property (9.73 emu g-1) of the nanoflowers resulted in higher retrievability and reusability after repeated usage. Furthermore, the catalytic activity of lipase/Cu3(PO4)2 hybrid nanoflowers was investigated and the ideal conditions were determined whereby, the maximum activity was calculated to be 1511 ± 44 U g-1, showing a catalytic enhancement of 89% in comparison to free lipase. The reusability study showed that, after 5 cycles, the magnetic lipase/Cu3(PO4)2 nanoflowers successfully retained 60% of its initial activity. From the results obtained, it is worth noting that, the magnetic lipase/Cu3(PO4)2 hybrid nanoflowers are highly efficient in industrial biocatalytic applications.

Determine both the conformation and orientation of a specific residue in α-synuclein(61–95) even in monolayer by 13C isotopic label and p-polarized multiple-angle incidence resolution spectrometry (pMAIRS)

Protein’s magic function stems from its structure and various analytical techniques have been developed for it. Among proteins, membrane proteins are encoded 20–30% of genomes, whereas cause challenges for many analytical techniques. For example, lots of membrane proteins cannot form single crystal structure required by X-ray crystallography. As for NMR, the measurements were hindered by the low tumbling rates of membrane (i.e., phospholipid bilayers) where membrane proteins exist. In addition, membrane proteins usually lay parallel to the surface of phospholipid bilayers or form transmembrane structure. No matter parallel or perpendicular to phospholipid bilayers surface, membrane proteins form monolayer structure which is also difficult for X-ray and NMR to provide high-resolution results. Because NMR and X-ray crystallography are the two major analytical techniques to address protein’s structure, membrane proteins only contribute 2.4% to the solved protein databank. Surface FT-IR techniques can evaluate the conformation and orientation of membrane proteins by amide I band. Specifically for α-helical peptides/proteins, the orientation of the axis is critical to decide whether proteins form transmembrane structure. Notice that the traditional FT-IR can only provide “low-resolution” results. Here, ¹³C isotope was introduced into the nonamyloid component (NAC), which spans residues 61–95 of α-synuclein (α-syn). Then, p-polarized multiple-angle incidence resolution spectrometry (pMAIRS) was used to determine the orientation of a specific residue of α-helical NAC in monolayer. In general, pMAIRS is a novel technique to work complementary with X-ray and NMR to address membrane peptides/proteins structure with high resolution even in monolayer.

FT-IR Spectral Signature of Sensitive and Multidrug-Resistant Osteosarcoma Cell-Derived Extracellular Nanovesicles

Osteosarcoma (OS) is the most common primary bone cancer in children and adolescents. Despite aggressive treatment regimens, the outcome is unsatisfactory, and multidrug resistance (MDR) is a pivotal process in OS treatment failure. OS-derived extracellular vesicles (EVs) promote drug resistance to chemotherapy and target therapy through different mechanisms. The aim of this study was to identify subpopulations of osteosarcoma-EVs by Fourier transform infrared spectroscopy (FT-IR) to define a specific spectral signature for sensitive and multidrug-resistant OS-derived EVs. EVs were isolated from sensitive and MDR OS cells as well as from mesenchymal stem cells by differential centrifugation and ultracentrifugation. EVs size, morphology and protein expression were characterized. FT-IR/ATR of EVs spectra were acquired in the region of 400–4000 cm⁻¹ (resolution 4 cm⁻¹, 128 scans). The FT-IR spectra obtained were consistently different in the EVs compared to cells from which they originate. A specific spectral signature, characterized by a shift and a new band (1601 cm⁻¹), permitted to clearly distinguish EVs isolated by sensitive and multidrug-resistant OS cells. Our data suggest that FT-IR spectroscopy allows to characterize and define a specific spectral signature for sensitive and MDR OS-derived EVs.

Metal ion type significantly affects the morphology but not the activity of lipase–metal–phosphate nanoflowers

Using different metal ions to prepare hybrid lipase nanoflowers resulted in a variety of different morphologies, but did not significantly affect the specific activity of the enzyme.

Surfactant-activated lipase hybrid nanoflowers with enhanced enzymatic performance

Increasing numbers of materials have been extensively used as platforms for enzyme immobilization to improve catalytic performance. However, activity of the most of the enzymes was declined after immobilization. Here, we develop a surfactant-activated lipase-inorganic flowerlike hybrid nanomaterials with rational design based on interfacial activation and self-assembly. The resulting surfactant-activated lipase-inorganic hybird nanoflower (activated hNF-lipase) exhibited 460% and 200% higher activity than native lipase and conventional lipase-inorganic hybird nanoflower (hNF-lipase). Furthermore, the activated hNF-lipase displayed good reusability due to its monodispersity and mechanical properties, and had excellent long-time stability. The superior catalytic performances were attributed to both the conformational modulation of surfactants and hierarchical structure of nanoflowers, which not only anchored lipases in an active form, but also decreased the enzyme-support negative interaction and mass-transfer limitations. This new biocatalytic system is promising to find widespread use in applications related to biomedicine, biosensor, and biodiesel.