Integrative In Situ Photodynamic Therapy-Induced Cell Death Measurement of 3D-Bioprinted MCF-7 Tumor Spheroids.

The development of new in vitro models that closely mimic the tumor microenvironment (TME) to evaluate the efficacy of anticancer drugs has received great attention. In this study, a three-dimensional (3D) bioprinted Michigan Cancer Foundation-7 (MCF-7) cancer spheroid-embedded hydrogel model was suggested for integrative in situ determination of the half-maximal inhibitory concentration (IC50) values of photosensitizers (PSs). The MCF-7 cell-laden alginate/gelatin hydrogel was printed for the fabrication of tumor spheroids. The hydrogel was used to mimic the extracellular matrix (ECM) surrounding the cancer cells in the TME. The fluorescence intensities corresponding to photodynamic therapy (PDT)-induced death of tumor spheroids probed by the laser showed a random distribution in the hydrogel, regardless of the focus of the laser and the vertical-axis direction in which the laser was passed. These results enabled integrative in situ measurement of all tumor spheroids probed by the laser without needing to separate the tumor spheroids in the hydrogel and measure them individually. When compared with two-dimensional (2D) monolayer cultures, very large IC50 values of the PSs, chlorin e6 (Ce6) and sulfonated tetraphenyl porphyrin (sTPP), were achieved in MCF-7 spheroid-embedded hydrogels mainly due to the drug resistance of the tumor spheroids. Additionally, the heterogenic PDT response of single MCF-7 cancer cells in a single tumor spheroid was observed through 3D imaging of irregular apoptosis in a single spheroid since single tumor spheroids showed a heterogenic PDT response. Furthermore, the laser-power-dependent IC50 values of PSs were obtained using the MCF-7 spheroid-embedded hydrogel model.

Determination of chlorogenic acids and caffeine in homemade brewed coffee prepared under various conditions.

Coffee, a complex mixture of more than 800 volatile compounds, is one of the most valuable commodity in the world, whereas caffeine and chlorogenic acids (CGAs) are the most common compounds. CGAs are mainly composed of caffeoylquinic acids (CQAs), dicaffeoylquinic acids (diCQAs), and feruloylquinic acids (FQAs). The major CGAs in coffee are neochlorogenic acid (3-CQA), cryptochlorogenic acid (4-CQA), and chlorogenic acid (5-CQA). Many studies have shown that it is possible to separate the isomers of FQAs by high-performance liquid chromatography (HPLC). However, some authors have shown that it is not possible to separate 4-feruloylquinic acid (4-FQA) and 5-feruloylquinic acid (5-FQA) by HPLC. Therefore, the present study was designated to investigate the chromatographic problems in the determination of CGAs (seven isomers) and caffeine using HPLC-DAD. The values of determination coefficient (R2) calculated from external-standard calibration curves were >0.998. The recovery rates conducted at 3 spiking levels ranged from 99.4% to 106.5% for the CGAs and from 98.8% to 107.1% for the caffeine. The precision values (expressed as relative standard deviations (RSDs)) were <7% and <3% for intra and interday variability, respectively. The tested procedure proved to be robust. The seven CGAs isomers except 4-FQA and 5-FQA were well distinguished and all gave good peak shapes. We have found that 4-FQA and 5-FQA could not be separated using HPLC. The method was extended to investigate the effects of different brewing conditions such as the roasting degree of green coffee bean, coffee-ground size, and numbers of boiling-water pours, on the concentration of CGAs and caffeine in homemade brewed coffee, using nine green coffee bean samples of different origins. It was reported that medium-roasted, fine-ground coffees brewed using three pours of boiling water were the healthiest coffee with fluent CGAs.