Cary 3500 uv vis spectrophotometer

Organic solvents (1-octanol)/aqueous (100 mM phosphate buffer at pH 7.4) phase partition for CAPE and its analogues were conducted using the shake-flask method [38 (link)], with the concentration in each phase determined by a Cary 3500 UV–Vis spectrophotometer (Agilent, Santa Clara, CA, USA).

The turbidity of dextran samples with various material properties and solution conditions was obtained by measuring solution absorbance at 400 nm wavelength as a function of temperature. All samples were characterized in a glass cuvette for turbidity assay using a Cary 3500 UV–Vis spectrophotometer (Agilent Technologies, Santa Clara, CA) equipped with a temperature-controlled cell holder. The solution temperature was increased from 10 to 60 °C at a constant 1 or 2 °C/min interval heating scanning rate until a plateau was achieved in absorbance value. A baseline absorbance curve of PBS solution was collected as a reference before each sample run. The transition temperature was determined considering the start of the rise in the absorbance value of the UV–Vis spectra.

An Agilent Cary 3500 UV-Vis spectrophotometer (Melbourne, Australia) was used to obtain UV absorbance spectra. Samples were prepared in water at room temperature. A 1 cm quartz cuvette was used to collect data from 190–400 nm, with water as the reference. To determine the extinction coefficients, a concentrated stock solution of each complex (1 mM) was initially prepared in water and aliquoted (2–5 µL) into a cuvette containing water (3000 µL). Experiments were repeated in triplicate and the average extinction coefficients were calculated.

The photoprotective capacity of SR hydroethanolic extract and its fractions was determined spectrophotometrically according to the method described by Oliveira et al. [70 (link)]. As a universal measure of photoprotective activity, the sun protection factor (SPF) was calculated. Solutions of examined samples at concentrations of 0.05, 0.1 and 0.2 mg/mL were prepared in phosphate buffer (pH 7.0). Absorption of each solution was measured in triplicate at 290–320 nm, with 5 nm increments, using Agilent Cary 3500 UV-Vis Spectrophotometer. Phosphate buffer was used as a blank. SPF was calculated using the following formula: $$\mathrm{SPF}=\mathrm{CF}\times {\displaystyle \sum }_{290}^{320}\mathrm{EE}\left(\mathsf{\lambda }\right)\mathrm{I}\left(\mathsf{\lambda }\right)\mathrm{Abs}\left(\mathsf{\lambda }\right)$$
where CF is the correction factor (equal to 10); EE (λ) is the erythemal effect spectrum; I (λ) is the solar intensity spectrum, and Abs (λ) is the absorbance of the solution at a wavelength (λ). The values of EE × I are constants, and were determined by Sayre et al. [71 (link)].

An amount of 1 g of 2-chlorotrityl chloride resin (approx. 1.6 mmol chloride) was pre-swelled for 30 min in 10 mL of dry dichloromethane (DCM) in a syringe reactor (Multisyntech, Witten, Germany). Then DCM was removed by vacuum filtration. The resin was agitated for 60 min with a solution containing 3 mL of N,N-dimethylformamide (DMF), 4 mL of dry DCM, 0.6 mmol of 4-(Fmoc-aminomethyl)benzoic acid (Fmoc-PAMBA-OH) and 1.8 mmol N,N-diisopropylethylamine (DIPEA). Afterwards, the solution was discarded by vacuum filtration and a capping solution containing 4 mL DCM, 3 mL methanol and 500 $\mathrm{\mu }$ L DIPEA was added. After agitation for 30 min, the solution was removed and the resin was washed three times with DMF and DCM. The resin was dried under high vacuum and three samples were taken for loading determination. The samples were agitated with 1 mL of 20% piperidine in DMF at RT for 1 h. 50 $\mathrm{\mu }$ L of the supernatant of each sample was diluted with 1.95 mL DMF and the absorbance at 301 nm was measured with a Cary 3500 UV-Vis spectrophotometer (Agilent Technologies, U.S.). As blank solution, 50 $\mathrm{\mu }$ L of 20% piperidine in DMF diluted with 1.95 mL DMF was used. The resin loading was determined based on the following formula: $$\text{resin load}[\text{mmol}/\text{g}]=(A_{301}\text{nm}\times 1000)/(\text{resin mass}[\text{mg}]\times 7800[\text{L}\times {\text{mol}}^{-1}\times {\text{cm}}^{-1}]\times 0.025)$$