P. K. Hashim - Research

Our research explores how molecular structure, geometry, and external stimuli can be used to precisely control material function. We combines synthetic chemistry, spectroscopy, materials characterization, and computational approaches to develop next-generation functional molecular systems.

Visible-light-responsive azo-heteroarene photoswitches

We develop light-controlled molecules that can change their shape when exposed to visible light. These “molecular switches” are designed using a new chemical structure that responds efficiently to blue and green light—making them more practical and safer than traditional systems that require ultraviolet light. Our research showed that small changes in molecular design can significantly improve how these switches absorb light and how reliably they move between two states. By carefully tuning their structure, we created systems that respond selectively to specific wavelengths and can repeatedly switch back and forth in a controlled way (J. Am. Chem. Soc., 2023; Org. Biomol. Chem., 2025). This work opens the door to new applications in smart materials, responsive polymers, nanotechnology, and future biomedical tools where light can be used as a precise, non-invasive control signal.

Smart pH Indicators for Sensitive Environments

We discovered a new type of pH indicator that can detect very small changes in pH near neutral conditions—an area that is especially important in biological systems. These newly designed molecules display distinctive light absorption in water and undergo clear, visible color changes within a narrow pH range. Unlike conventional indicators, our system is sensitive enough to function in complex environments. We demonstrated their practical use by monitoring subtle pH changes in cell culture media containing growing cancer cells (Chem. Eur. J. 2025).

Using Artificial Intelligence to Design Light-Responsive Molecules

Photoswitches are special molecules that change their shape when exposed to light. To design useful photoswitches, scientists need to know two key things: (1) What color of light triggers the change, and (2) How stable the switched form is over time. Traditionally, answering these questions requires complex and time-consuming quantum chemical calculations. As the number of potential molecules grows, this process becomes increasingly expensive and slow. In our recent research, we took a different approach of using machine learning (artificial intelligence) to predict these properties quickly and efficiently. Instead of running heavy calculations, we represent molecules as simple graph structures and train computer models to learn how molecular structure relates to light responsiveness and stability. This AI-driven strategy allows faster screening of new candidates and accelerates the discovery of next-generation light-controlled materials and technologies.

Light-Controlled Medicines (Photopharmacology)

We are working on a new approach to medicine where drugs can be controlled by light. Instead of being constantly active, these special molecules can be switched “ON” only when exposed to a specific color of light. This allows much more precise control over when and where a drug works. In our study, we redesigned a known molecule that activates an important biological system called the Wnt pathway, which helps control cell growth and development. By adding a light-sensitive switch to the molecule, we created a version that only becomes active after shining visible light on it. We showed that the light-activated form works almost as strongly as the original drug. Even more importantly, we demonstrated that by shining light on a specific area of cells, we could activate the pathway only in that exact location. This research moves us closer to future medicines that can be turned on precisely where they are needed, potentially reducing unwanted side effects and improving treatment accuracy.

Ultra-Small Drug Delivery Systems

We also explore how synthetic chemistry can be used to design ultra-small drug delivery systems that safely transport therapeutic molecules into cells. We developed a unique method called template-assisted polymerization, which creates a thin protective coating around fragile biological molecules such as siRNA. This protective layer shields the therapeutic molecule from degradation, helps it enter cells, and then safely releases it once inside. The same strategy was successfully applied to deliver sensitive proteins into cells. We also demonstrated that by attaching targeting molecules—such as transferrin—the delivery system could penetrate deeply into tumor-like structures, improving precision and effectiveness. Recently, I reviewed and expanded this concept for designing highly controlled drug carriers smaller than 100 nanometers, highlighting their potential for next-generation nanomedicine.

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