# A Novel Method for Real-Time Quantification of Radioligand Binding to Living Tumor Cells In Vitro

## TL;DR

This paper introduces a new method to measure how radioligands bind to living tumor cells in real time, helping improve their use in medicine.

## Contribution

A novel real-time quantification method for radioligand binding to living cells under in vivo-like conditions is presented.

## Key findings

- The detection efficiency of 125I was 65 cps/kBq for radioligand bound to the cells.
- The kon and koff values were determined as 3.2–7.9 × 104 M−1 s−1 and 0.11–4.2 × 10–5 s−1, respectively.
- The method enables rapid evaluation of radioligands for diagnostic and therapeutic applications.

## Abstract

Real-time quantification of radioligand binding to cells under in vivo-like conditions improves evaluation of clinical potential.

SKOV-3 tumor cells were grown in a monolayer on a thin glass plate placed in a sealable shallow chamber with a continuous flow of 125I-trastuzumab solution. The time-dependent cell binding was measured using a NaI detector, and the binding parameters were derived by computational analysis.

The detection efficiency of 125I was 65 cps/kBq for radioligand bound to the cells. Experiments were analyzed to find the values of kon and koff. The resulting kon was 3.2–7.9 × 104 M−1 s−1 and koff was 0.11–4.2 × 10–5 s−1.

Radioligands can be rapidly evaluated by binding to living cells for selection and optimization of radioconjugates for diagnostic and therapeutic purposes.