Lambda 950 spectrophotometer

The total superoxide dismutase (SOD) activity was determined according to the method of Misra and Fridovich (62 (link)) at 30°C. Supernatant (10 µl) was added to 960 µl of carbonate buffer (0.05 M, pH 10.2, 0.1 mM EDTA). Then epinephrine 30 mM (30 µl) (in 0.05% acetic acid) was added, and absorbance was measured at 480 nm for 4 min on a PerkinElmer Lambda 950 spectrophotometer. SOD activity was expressed in unit per milligram protein. Amount of enzyme that inhibits the oxidation of epinephrine by 50% was defined as 1 U.

UV-visible absorbance spectra were obtained using a PerkinElmer Lambda 950 spectrophotometer equipped with deuterium and halogen lamps. Photoluminescence measurements were performed using a Fluoromax 4 from Horiba Scientific, and photoluminescence quantum yields were determined using a quanta-phi integrating sphere accessory according to a previously described procedure.69 (link) Powder X-ray diffraction (XRD) was measured on a PANalytical X'Pert Powder X-ray diffractometer. Transmission electron microscopy (TEM) was performed on a FEI T12 BioTWIN and a FEI Talos F200X. Fourier transform infrared (FT-IR) spectra were obtained using a PerkinElmer Spectrum One FT-IR Spectrometer operating with an attenuated total reflectance (ATR) accessory.

SEM images were obtained using a Nova NanoSEM 450 scanning electron microscope (FEI Co., Netherlands). An XPS system (Thermo ESCALAB 250XI) was used to acquire the XPS spectra. The crystal structure of the films was characterized using XRD with an Empyrean X-ray diffractometer with Cu Kα radiation (PANalytical B.V. Co., Netherlands). ToF-SIMS depth profiles were carried out using an IonToF ToF-SIMS 5 instrument (IONTOF Co., Germany). The work functions of the samples were investigated using a KP Technology Ambient Kelvin probe system package. The time-resolved PL studies were performed using an Edinburgh FLS920 fluorescence spectrometer (Edinburgh Co., UK). The UV–vis spectra were recorded using a Lambda 950 spectrophotometer (PerkinElmer Co., USA). Photovoltaic measurements employed a black mask with an aperture area of 1 cm² under standard AM1.5G simulated sunlight (Oriel, model 9119) and the simulated light intensity was calibrated with a silicon photodiode. Incident photon-to-electron conversion efficiency (IPCE) was measured using a Newport IPCE system (Newport, USA). The light-soaking stability was measured with a CHI1000c multichannel electrochemistry workstation (Chenhua, Co., China).

Powder X-ray diffraction (PXRD) patterns were measured by a rotating anode X-ray powder diffractometer (Rigaku) using Cu Kα radiation (λ = 1.54178 Å). Field-emission scanning electron microscopy (FESEM) images were obtained from a JSM-6360LV microscope (JEOL). Transmission electron microscopy (TEM) images, high-resolution TEM (HRTEM) images and selected area electron diffraction (SAED) images were taken on a JEM-1400 (JEOL) microscope operating at an acceleration voltage of 100 kV. Atomic force microscopy (AFM) using a DI system (Veeco Instruments) was used to characterize nanosheet thickness. The UV-vis absorption spectra of samples were collected on a Lambda 950 spectrophotometer (PerkinElmer) with QS-grade quartz cuvettes (110-QS; Shimadzu).
Prior to characterization by TEM and AFM, the nanosheets were obtained from Cu-MOF membranes by ultrasound treatment in ethanol. Then, the ethanolic suspension was dropped onto holey, carbon-coated, carbon-supported copper grids and piranha-cleaned Si, respectively, and then dried naturally.

Transmission electron microscopy (TEM) was performed on a JEOL-2010 instrument (JEOL, Tokyo, Japan) at 200 kV. Fourier transform infrared (FTIR) spectra were collected in the wavenumber range of 4000–400 cm⁻¹ using a Nicolet 360 FTIR spectrometer (Nicolet, Madison, WI, USA). X-ray photoelectron spectroscopy (XPS) was performed using an ESCALAB 250 spectrometer (VG Scientific, London, England) with monochromatic Al Kα radiation (hν = 1486.6 eV), and the binding energy calibration was based on C 1s (284.6 eV). UV–vis absorption spectra were recorded on a PerkinElmer Lambda 950 spectrophotometer (PerkinElmer, Waltham, MA, USA). Excitation and emission spectra were collected using a Hitachi F-7000 fluorescence spectrophotometer (Hitachi, Tokyo, Japan). The QY of the CDs was measured at an excitation wavelength of 360 nm using quinine sulfate as a standard (QY = 54%) [6 (link)]. Confocal microscopy analysis was performed using an Olympus FluoView 500 laser scanning confocal microscope (Olympus, Tokyo, Japan), and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay of the obtained CDs was used to quantify the viability of HeLa cells [40 (link)].

Samples of raw MWNTs and PEG functionalized MWNTs were scanned by a transmission electron microscope (Hitachi, Japan) at an acceleration voltage of 80 kV. The sizes of MWNTs on TEM images were measured using image analysis software, Image J (Ver. 1.48). The 1H NMR of raw MWNTs and PEG functionalized MWNTs were recorded at 400 Hz (AVANCE III, Bruker, Switzerland). Optical absorption of MWNTs (10 μg/ml) was measured with a Lambda 950 spectrophotometer (PerkinElmer, Inc.) in a wavelength range of 200 to 1,400 nm. The absorbance of deionized water was set as a zero baseline.