Analytical and bioanalytical technologies for characterizing antibody-drug conjugates.

Antibody-drug conjugates (ADCs) require multiple assays for analytical and bioanalytical characterization due to their heterogeneous and dynamic nature. These assays can help address questions from the drug-loading distribution following conjugation to exposure-response relationships after dosing in vivo. This review describes new assay technologies that have been developed for physiochemical characterization and determination of pharmacokinetic parameters of ADCs.

State-resolved studies of biexcitons and surface trapping dynamics in semiconductor quantum dots.

Biexcitons in strongly confined, colloidal CdSe quantum dots were investigated with excitonic state selectivity combined with 10 fs temporal precision. Within the first 50 fs, the first excited state of the biexciton was observed. By 100 ps, mixed character biexcitons were observed, comprised of a core exciton and a surface trapped exciton. The size dependence of the biexciton binding energies is reported for these specific biexcitons. Analysis of the spectral signatures of each biexcitonic state yields a quantitative measure of enhanced excited state trapping rates at the surface of the quantum dots. By comparing the biexcitonic signals to the state-filling signals, we show that it is primarily the holes which are trapped at the interface on the 100 ps time scale.

Noise analysis and noise reduction methods in kilohertz pump-probe experiments.

We analyze sources of noise in kilohertz frequency pump/probe experiments and present a method for reducing experimental noise by identifying and filtering noisy shots. The power spectrum of instrumental noise shows high frequency, small amplitude modulations which cannot be averaged out. A histogram analysis shows that low frequency, large amplitude signals pose a serious obstacle to signal averaging for improved signal to noise. In kilohertz frequency pump/probe experiments, this low frequency noise typically arises from laser scatter due to bubbles, dust, and defects. We quantify the effectiveness in analyzing and rejecting these large amplitude signals which can produce a hindrance to the effectiveness of signal averaging.