Capacitance spectroscopy enables real-time monitoring of early cell death in mammalian cell culture.

Background/aims: Previous work developed a quantitative model using capacitance spectroscopy in an at-line setup to predict the dying cell percentage measured from a flow cytometer. This work aimed to transfer the at-line model to monitor lab-scale bioreactors in real-time, waiving the need for frequent sampling and enabling precise controls.

Methods And Results: Due to the difference between the at-line and in-line capacitance probes, direct application of the at-line model resulted in poor accuracy and high prediction bias.

Rapid at-line early cell death quantification using capacitance spectroscopy.

Cell death is one of the failure modes of mammalian cell culture. Apoptosis is a regulated cell death process mainly observed in cell culture. Timely detection of apoptosis onset allows opportunities for preventive controls that ensure high productivity and consistent product quality.

First-Principles and Empirical Approaches to Predicting In Vitro Dissolution for Pharmaceutical Formulation and Process Development and for Product Release Testing.

This manuscript represents the perspective of the Dissolution Working Group of the International Consortium for Innovation and Quality in Pharmaceutical Development (IQ) and of two focus groups of the American Association of Pharmaceutical Scientists (AAPS): Process Analytical Technology (PAT) and In Vitro Release and Dissolution Testing (IVRDT). The intent of this manuscript is to show recent progress in the field of in vitro predictive dissolution modeling and to provide recommended general approaches to developing in vitro predictive dissolution models for both early- and late-stage formulation/process development and batch release. Different modeling approaches should be used at different stages of drug development based on product and process understanding available at those stages.

Comparison of near infrared and microwave resonance sensors for at-line moisture determination in powders and tablets.

In this paper we demonstrate the feasibility of replacing KF for water content testing in bulk powders and tablets with at-line near infrared (NIR) or microwave resonance (MR) methods. Accurate NIR and MR prediction models were developed with a minimalistic approach to calibration. The NIR method can accurately predict water content in bulk powders in the range of 0.

Comprehensive determination of extractables from five different brands of stoppers used for injectable products.

Five commonly used stopper formulations were tested for extractables using three different vehicles (pH 3 citrate buffer with 20% w/v sulfobutylether-beta-cyclodextrin, pH 8 phosphate buffer and 50/50 v/v polyoxyethylated castor oil/dehydrated alcohol). The stoppers, made from butyl and halobutyl rubbers, coated and uncoated with proprietary films, were stored in contact with each vehicle for up to 6 months at 40 degrees C/75% relative humidity (RH) or for up to 24 months at 25 degrees C/60% RH. Samples were analyzed for the presence of extractables using inductively coupled plasma-atomic emission spectroscopy, ion chromatography, high-performance liquid chromatography, and gas chromatography.

Two-photon photochromism of a diarylethene enhanced by Förster resonance energy transfer from two-photon absorbing fluorenes.

Resonance energy transfer from two-photon absorbing fluorene derivatives to the photochromic compound 3,4-bis-(2,4,5-trimethyl-thiophen-3-yl)furan-2,5-dione (PC 1) is investigated in hexane under one- and two-photon excitation. The quenching of the steady-state fluorescence of donor molecules in the presence of the diarylethene acceptor is used to study the nature of resonance energy transfer. The Förster distances and critical acceptor concentrations are determined for nonbound donor-acceptor pairs in homogeneous molecular ensembles.

Synthesis and characterization of new fluorene-based singlet oxygen sensitizers.

The synthesis, photophysical characterization, and determination of singlet oxygen quantum yields (Phi(Delta)) for a class of fluorene derivatives with potential application in two-photon photodynamic therapy (PDT) is reported. It has been demonstrated that these compounds possess the ability to generate singlet oxygen (1O2) upon excitation. A photochemical method, using 1,3-diphenylisobenzofuran (DPBF) as 1O2 chemical quencher, was employed to determine the singlet oxygen quantum yields (Phi(Delta)) of the fluorene-based photosensitizers in ethanol.