Molecular Sensors and Fluorescent PET: The Life and Legacy of AP da Silva

AP da Silva, a pioneer in photochemistry and molecular sensing, shares how humble beginnings in Colombo sparked a lifelong curiosity about transforming matter with light. From a Belfast PhD to developing fluorescent molecular sensors that monitor ions in blood, his work culminates in portable, point‑of‑care devices that combine chemistry with computation. The story weaves serendipity, mentorship, and a drive to translate lab ideas into life‑saving technologies, including collaborations with Roche on blood analysis chips and the broader potential of molecular logic in medicine.

Introduction: A scientist who bridges chemistry and computation

AP da Silva, a renowned figure in photochemistry, explains how early encounters with science and serendipity steered his career toward molecular sensors that operate at extremely small scales. He describes how his research evolved from fundamental photochemistry to practical devices that read information from light, enabling diagnostic capabilities in clinical settings and potentially inside living systems. The discussion emphasizes the recurring theme of kindness and chance in scientific progress, a thread that runs through his life from Sri Lanka to Northern Ireland.

"Serendip is an old name for Sri Lanka, which translates as golden island in the Indian epics" - AP da Silva

From Sri Lanka to Belfast: Education and mentorship

The conversation traces his childhood in Colombo, where deprivation did not dampen curiosity. He recounts the pivotal mentorship of a teacher who helped him see chemistry as a way to transform matter and connect with the world around him. A crucial move to Belfast for a PhD in organic photochemistry opened doors to new ideas about how light interacts with molecules and how that interaction can be harnessed to sense ions and other targets in biological environments.

From Photochemistry to Fluorescent PET Sensors

DA Silva explains the core idea behind fluorescent PET sensors: by pairing a fluorescent dye with a receptor, and tuning their interface, light energy can be used to control electron transfer that depends on the presence of a specific ion. When an ion like sodium binds, it alters the electron transfer, allowing the sensor to emit light that corresponds to the ion concentration. This modular approach made it possible to design sensors for various salts and minerals, transforming basic photochemistry into practical, biocompatible sensors that can operate in tiny volumes.

"I realised fairly quickly that I couldn't really do photochemistry because chemistry would involve transforming molecule A into molecule B, but then I have to find out what molecule B is" - AP da Silva

Clinical Translation: Sodium testing and Roche collaboration

The dialogue moves to a turning point when a major company, Roche, sought to develop a point‑of‑care blood analyzer. They invited AP to implement his modular fluorescent sensor concept on a compact chip that could measure multiple ions like sodium, potassium, and calcium in blood in under a minute. The conversation explains how the single microchip, with six stations, could deliver rapid, accurate measurements and how Roche’s clout helped take the technology global. This segment illustrates how a scientific principle becomes a medical device that can change clinical workflows and patient outcomes.

"Sodium that exists in the body is missing an electron" - AP da Silva

Molecular Computing and Biocompatible Logic

AP discusses how the sensors he developed exist at the boundary between chemistry and computation. The binary on/off nature of light emission mirrors digital logic, enabling molecular systems to perform information processing at scales far smaller than traditional silicon circuitry. The interview delves into the potential of molecular logic gates to operate inside cells, enabling fluorescence guided by multiple parameters such as pH or enzyme activity, and the potential to guide surgical decisions or diagnostics with highly specific signals.

Applications in Tumor Surgery and Beyond

The talk extends to future medical applications, including fluorescence guided tumor surgery where multiple molecular parameters can delineate tumor boundaries more clearly than conventional methods. AP emphasizes the promising, but still early, stage of animal trials, and the need for adventurous institutions to explore this literature while serendipity continues to play a role in discovery.

Awards, Retirement, and the Legacy

We close with reflections on recognition, including a blue plaque from the Royal Society of Chemistry and a Lifetime Achievement Award from Queen's University Belfast. AP shares his thoughts on retirement, staying connected to the lab, mentoring the next generation, and watching ideas live on through students who carry forward his work into industry and academia.

"Blue plaques are normally given to dead people" - AP da Silva