Measuring the Invisible: How Mass Spectrometry and Light Scattering Reveal Molecules at the Nanoscopic Scale

Overview

In this lecture, the speaker explains why mass matters in science, how measuring tiny masses enables identification of molecules, and how advances in mass spectrometry and mass photometry are transforming drug development, diagnostics, and biotechnology.

Key themes

From Dalton’s atomic theory to today's single-molecule measurements, the talk covers mass as a unique signature, the evolution of mass spectrometry, the advent of native MS, and the emergence of mass photometry as a practical method for observing individual biomolecules in solution. It also recounts a startup journey that translated fundamental research into a commercial instrument and highlights the role of risk, IP, and collaborative science in delivering real-world impact.

Introduction: Why measure mass?

The talk opens by arguing that mass measurement is foundational, enabling precise identification of molecules and, in turn, enabling security, healthcare, and research applications. Mass, unlike macroscopic weight, reveals the exact composition of tiny assemblies when assessed with sufficient precision.

From atoms to identifiers

Historically, mass has connected to what matter is made of, as in Daltonian chemistry. At the molecular scale, measuring mass becomes a unique barcode that can distinguish, for example, RDX from other compounds or anabolic steroids metabolites. The speaker uses these examples to motivate the development of mass measurement technologies that operate at the single-molecule level.

Mass spectrometry: tracing mass/charge to identity

Two Royal Society fellows, Thomson and Aston, developed mass spectrometry as a workhorse for identifying molecules by their mass-to-charge ratio. The technique separates ions by how they bend in an electric field, allowing detection of distinct masses. Its impact spans drug testing, airport security, environmental testing, and clinical research, and it remains a cornerstone of modern analytical chemistry and life sciences.

The challenge of growing complexity

As drugs evolved from small molecules to large biomolecules like antibodies and gene therapies, measuring mass became harder due to broadening mass distributions and poor gas-phase stability. Carol Robinson and colleagues pioneered native mass spectrometry to analyze proteins in conditions closer to their native state, enabling the study of larger complexes and biologics.

Beyond MS: the idea of counting atoms with light

The speaker then describes a complementary idea: counting atoms directly by observing light interactions. Single atoms and molecules can be visualized with advanced optical techniques, provided the detector and environment are stable enough. This leads to the concept of mass photometry, where the scattering of light by single biomolecules attached to a surface yields a mass-dependent signal.

Engineering a new instrument: stability, noise, and scale

Building an ultra-sensitive microscope required extraordinary stability. The talk covers vibration isolation, thermal drift control, and acoustic isolation, illustrating the engineering challenges and solutions with vivid anecdotes from the Oxford team. The result is a method that can observe individual molecules in liquid, a feat previously thought impossible with light scattering alone.

From bench to business: the startup story

A spontaneous pub conversation sparked the mass measurement idea. The team built a compact instrument that could detect a bound biomolecule by a small change in optical signal, then demonstrated it at conferences, securing early customers and venture funding. Over seven years, the company expanded to hundreds of instruments, thousands of users, and tens of millions invested, with a focus on next-generation therapeutics and complex biologics. A second startup applying similar light-scattering principles to batteries shows the method’s versatility.

Philosophy of risk and science policy

The talk closes with reflections on risk-taking in fundamental research, the value of taxpayer funding, and the importance of people who persevere through failures. IP ownership, university licensing, and the broader ecosystem that connects academia with industry are highlighted as essential ingredients for transformative science.