Molecular Machines: Nobel Prize in Chemistry 2016 Explained

Liquid crystal displays use rod-like molecules organized in helical arrangements, where color depends on helix pitch. Doping with molecular motors enables light-powered color-changing displays without electricity. Amplification of molecular motion to microscopic scales (at least one million-fold) enables practical applications. Liquid crystal polymers create artificial muscles that contract/expand under light, bending and grabbing objects autonomously. 3D printing with responsive materials creates flapping wings. Amphiphilic motors self-assemble into nano-fibers forming artificial muscles (95% water, 5% active material) that contract under light. Combining motors with magnetic nanoparticles enables devices guided by magnetic fields and activated by light. Biocompatible systems support living stem cells, which differentiate based on surface cues. Carbon nanotubes with glucose-converting enzymes create autonomous nano submarines. These developments bridge molecular machines with biology, opening paths to medical applications.

This section demonstrates how molecular motors create responsive materials with transformative potential. The speaker shows how incorporating motors into liquid crystal polymers enables walking materials that bend and twist under light irradiation, with chirality determining directionality. Molecular cars (2 nm in size) demonstrate translation of motion from rotational to translational modes through proper stereochemical design, requiring opposite wheel rotation (meso structure) for forward motion. The emergence of artificial muscles from small molecules through self-assembly represents a major breakthrough—amphiphilic molecules containing motors self-assemble into fibers in water, organized by calcium ions into aligned structures. Remarkably, only 5% of the mass consists of molecular motors while 95% is water—yet sufficient collective motion produces observable actuation. These developments demonstrate how molecular-level design produces macroscopic mechanical effects, enabling applications from self-cleaning surfaces to potential biomedical devices.

Stimuli-responsive smart materials are chemical systems that can sense environmental changes (such as light, pH, temperature, or enzymes) and respond by changing their structure or function, enabling applications like targeted drug delivery where molecular capsules release contents only at specific locations in the body; these materials are typically created through bottom-up approaches where small molecular building blocks spontaneously self-assemble into responsive structures, as demonstrated by carbohydrate-based systems where glucose oligomers wrap around hydrophobic guests to form helical assemblies that can be reversibly broken apart and reassembled using molecular encapsulation and enzymatic triggers.

Smart materials (actuators) respond to external stimuli through molecular-level changes: electroactive materials (dielectric elastomers) expand when electrical current is applied due to charge polarization; thermoelectric materials convert temperature differences to electrical energy via Seebeck, Peltier, and Thomson effects; electro/magnetorheological fluids change viscosity reversibly under electrical or magnetic fields by organizing molecules into columns; and hydrophobic materials create self-cleaning surfaces through nanoscale structures that trap air, preventing water contact (lotus effect).

Molecular motors integrated into liquid crystal polymers create artificial muscles capable of contraction, expansion, and bending motions. Under light illumination, these motorized polymers exhibit programmed movements including outward-inward cycles and coordinated contractions. Surface-assembled molecular motors create responsive monolayers with synchronized rotational behavior, enabling nano-windmills and other surface-confined devices. Molecular motors incorporated into metal-organic frameworks (MOFs) create crystalline porous materials with dynamic properties, changing porosity in response to light. Photosensitizing layers combined with molecular motors create complete energy harvesting systems, converting light to mechanical work autonomously. These applications span self-cleaning surfaces, self-healing materials, biomedical devices, and sustainable energy conversion. The integration of molecular motors with diverse material platforms demonstrates the versatility of molecular nanotechnology for addressing global challenges in healthcare, environmental remediation, and renewable energy.

Nanobots solve the fundamental challenge of controlling drug delivery at the molecular level. Traditional drug development searches for safer drugs is flawed because drugs cannot be trained like soldiers. Nanobots act as well-programmed soldiers that can control existing drugs. They can safely sequester toxic drugs until reaching target cells. When unlocked, nanobots release cargo only at target sites, allowing even withdrawn toxic drugs to be used effectively. Nanobots can be programmed to search for specific tumor cells, ensuring only diseased cells are affected while healthy cells remain unharmed. Research teams have developed nanobots targeting approximately 10 types of cancer.

Nanobots are microscopic robots measuring 50 to 100 nanometers in width. They are designed for medical applications including DNA probes, cellular imaging materials, and targeted cell delivery vehicles. Ray Kurzweil believes nanobots represent the future of medicine, as they will be capable of repairing the human body at the cellular level, making humans immune to diseases and aging, and eventually to death.

Nanobots—microscopic robots operating at the nanoscale—hold promise for targeted drug delivery, tissue and organ regeneration at the cellular level, and radical transformation of disease treatment approaches. Researchers have already developed autonomous nanobots capable of navigating human tissues, suggesting widespread medical application within 5-10 years. However, safety concerns persist regarding potential viral spread and catastrophic scenarios involving self-replicating nanobots consuming organic matter.

Nanomedicine is the application of nanotechnology in medicine for disease prevention, diagnosis, and treatment. Nanoparticles can encapsulate or help deliver medication directly to cancer cells, minimizing damage to healthy tissue and potentially reducing toxic effects of chemotherapy. Nanobots are tiny packages that can complete tasks in an automated way, holding the ability to sense, respond, detect friend or foe within the body, and deliver payloads at the nano scale. They can be equipped with wireless transmitters to change treatment methods based on the state of medical conditions.

Nanocapsule technology enables revolutionary chemotherapy delivery by encapsulating drugs in sugar-based nanoparticles that evade immune detection and circulate for up to a week. Acidic tumor environments trigger capsule dissolution, releasing medication directly at target sites—reducing required doses by 20 times while eliminating side effects. Parallel advances in tissue engineering use biocompatible polysaccharide scaffolds that guide cell growth and regeneration. At the nanoscale, researchers understand and reproduce cellular communication mechanisms, paving the way for controlled tissue repair. Nanomaterials enable unprecedented neural tissue repair by stopping bleeding, creating scaffolds for cell migration, and promoting nerve fiber regrowth and reconnection. In animal studies, this technology restored visual function after optic nerve severance—demonstrating complete functional recovery of complex neural connections. Beyond neural applications, these materials address surgical challenges by providing antiseptic barriers that immobilize bacteria without killing beneficial microbes.

Quantum interference enables revolutionary molecular devices. Isomers with identical atoms and bonds can differ by factors of 1000 in conductance due to different interference patterns—one supporting constructive interference, another destructive. Electron tunneling through molecular barriers accumulates phase depending on path length and electronic structure. Fermi level alignment with molecular orbitals determines transport participation. Molecular geometry sensitivity allows single-bond rotations or anchor-point shifts to dramatically alter conductance. Molecular switches exploit this by toggling between ON (constructive interference, high conductance) and OFF (destructive interference, low conductance) states using light, electric fields, or chemical stimuli, achieving on-off ratios exceeding 1000:1. Molecular logic gates implement boolean operations through multiple independently modifiable sites, enabling AND gate functionality in single molecules. Ultra-sensitive chemical sensors detect single-target binding through conformational changes that trigger destructive interference, producing measurable conductance changes.

A molecular switch is a molecule that reversibly changes between an open (non-conducting) and closed (conducting) state. In the closed state, electrons conduct from one end to the other; in the open state, the circuit is broken. These switches can be controlled by specific light wavelengths: 365 nm light switches the molecule from open to closed (enabling conduction), while 600 nm light switches it back to open (stopping conduction). This light-controlled switching behavior allows molecular switches to function as optical electronic components and molecular logic gates, representing important applications in molecular computing and nanoscale electronic devices. The ability to control electron conduction through light input enables these molecules to perform logical operations, forming the basis for molecular-scale computing systems.

Researchers have created logic gates using molecular arrangements on surfaces. An AND gate can be constructed by setting up specific molecular configurations where bringing in control molecules at input positions triggers cascades that produce specific output changes. The output state depends on whether molecules are present at both input locations, demonstrating basic computational functionality at the molecular scale.

Molecular computers use molecular switches that perform logical operations (like AND/OR/NOT gates) through molecular interactions, enabling early detection of cellular dysfunctions by reformulating biomedical questions as logic problems; these tiny molecular machines can fit inside living cells and offer promising applications for diagnosing and treating diseases such as atherosclerosis.

Molecular logic extends PET sensor principles to perform computational operations. By combining multiple sensors with different logical functions (YES gates producing off-to-on signals, NOT gates producing on-to-off signals, PASS-1 gates maintaining constant output), complex computations can be performed at the molecular level. These logic gates operate on chemical inputs (substrates, reagents) and produce readable outputs (fluorescence intensity). The philosophy mirrors electronic logic devices: inputs come in, processing occurs, and outputs go out. This approach has spread to over 1,100 laboratories globally, including molecular biology labs working on synthetic biology and artificial life applications.