Scientists from Rice University have made a groundbreaking discovery regarding the destruction of cancer cells using light-induced vibrations. The research, published in Nature Chemistry, reveals that certain molecules can vibrate strongly when stimulated by near-infrared light, causing the cell membrane of cancerous cells to rupture.

The study focused on a small dye molecule commonly used for medical imaging. When exposed to near-infrared light, the atoms within the molecule vibrate in unison, forming a plasmon. This plasmonic motion led to a remarkable 99 percent efficiency in destroying lab cultures of human melanoma cells. In addition, half of the mice with melanoma tumors became cancer-free after treatment.

Rice chemist James Tour, who led the research, referred to these molecules as "molecular jackhammers," describing them as a new generation of molecular machines. Previous studies from Tour's lab utilized nanoscale compounds with light-activated paddlelike chains to drill through infectious bacteria, cancer cells, and treatment-resistant fungi. However, the molecular jackhammers function on an entirely different mechanism of action, making them more than a million times faster than the previous motor-driven drills developed by Nobel laureate Bernard Feringa.

What sets the molecular jackhammers apart is their activation potential. While the older nanodrills needed visible light for activation, the jackhammers can be activated with near-infrared light. This light enables deeper penetration into the human body, reaching organs and bones without causing damage to surrounding tissue. The ability to reach depths of up to 10 centimeters (~4 inches) marks a significant advance in the field.

These jackhammers are based on aminocyanine molecules, a class of fluorescent synthetic dyes commonly employed in medical imaging. Despite their familiarity and biocompatibility, their ability to be activated as plasmons remained unknown until this study.

Lead author Ciceron Ayala-Orozco explained the unique structure and properties of the identified molecular plasmons. These plasmons possess a near-symmetrical structure, with an arm serving as an anchor to the lipid bilayer of the cell membrane. This plasmonic effect, driven by the synchronized oscillation of the molecule's nuclei under the right stimulus, ultimately tears apart the cancer cells' membrane.

The researchers were careful to differentiate their technique from existing photodynamic and photothermal therapies. Ayala-Orozco emphasized that their approach utilizes mechanical forces at the molecular scale, offering a distinct way to treat cancer.

The molecular jackhammers' action was further analyzed by researchers at Texas A&M University using time-dependent density functional theory analysis. The cancer studies, conducted in mice, were carried out in collaboration with Dr. Jeffrey Myers at the University of Texas MD Anderson Cancer Center.

The potential of these molecular machines extends beyond cancer treatment. Researchers foresee applications in treating fungal infections, as well as combating antibiotic resistance by targeting bacteria with these drills.

The discovery of light-induced vibrations as a destructive force against cancer cells presents a promising avenue for future medical advancements. As scientists continue to explore the possibilities, this breakthrough may pave the way for more effective and precise treatments in the fight against cancer and other diseases.

Reference:
"Molecular Jackhammers Eradicate Cancer Cells by Vibronic-Driven Action"
Nature Chemistry, DOI: 10.1038/s41557-023-01383-y