Biophysics

Biophysics is an interdisciplinary scientific field that applies the theories, principles and quantitative methods of physics to understand biological structures, processes and systems. It spans all levels of biological organisation, from molecules and cells to tissues, organisms and populations. Because many biological phenomena arise from physical interactions, biophysics draws upon multiple disciplines including molecular biology, biochemistry, chemistry, nanotechnology, engineering, computational science and physiology.

Scope and Foundations of the Field

The term biophysics was introduced by Karl Pearson in the late nineteenth century and reflects an effort to bridge physical and biological sciences. Biophysics seeks to explain biological phenomena in terms of physical quantities such as energy, entropy, mechanical force, temperature, electric current and stress. This quantitative perspective overlaps with several other life sciences, but it is distinguished by its explicit grounding in physical laws and mathematical modelling.
Biophysical research extends from molecular and cellular processes—such as protein folding, gene regulation and enzyme kinetics—to large‐scale systems such as neural circuits, tissues, organs and ecological populations. Fields such as biomechanics, bioengineering, systems biology and computational biology each incorporate biophysical principles when analysing biological function.
Modern biophysics also includes specialist areas such as bioelectronics, nanomedicine and quantum biology, reflecting the increasing breadth of applications. Biological systems are frequently considered as interacting units whose collective behaviour can be described using tools from thermodynamics, statistical mechanics and chemical kinetics.

Molecular Biophysics and Structural Analysis

Molecular biophysics examines the physical basis of biomolecular interactions and processes within cells. Researchers in this domain investigate how DNA, RNA and proteins interact and how these interactions generate biological outcomes such as gene expression, protein synthesis and signal transduction.
A central component of molecular biophysics is the determination of biomolecular structures. Techniques such as X‐ray crystallography, nuclear magnetic resonance (NMR) spectroscopy and electron microscopy reveal atomic and near‐atomic resolution structures of proteins, nucleic acids, lipids and macromolecular complexes. Small‐angle scattering methods, including SAXS and SANS, provide complementary information about molecular shape and conformational change in solution.
Dynamic processes are equally important. Neutron spin echo spectroscopy can capture nanometre-scale motions within protein domains, while circular dichroism and dual polarisation interferometry allow measurements of conformational change. Single‐molecule techniques, such as optical tweezers and atomic force microscopy (AFM), enable the direct manipulation of biomolecules to monitor force generation, binding events and mechanical responses at the nanoscale.

Visualisation and Analytical Technologies

Biophysics employs an array of imaging and analytical technologies, many of which have become indispensable to modern biological research. Fluorescence microscopy—including confocal, super‐resolution and single‐molecule variants—provides the ability to track molecules and structures within living cells. Electron microscopy offers detailed ultrastructural information across tissues and organelles.
Computational modelling and simulation play an increasingly prominent role. Molecular dynamics simulations, protein structure prediction, docking algorithms and quantum chemical calculations allow researchers to explore biomolecular interactions in silico. Mathematical and statistical models support the analysis of sequence alignment, networks, population dynamics and phylogenetics.
The integration of experimental and computational approaches enables researchers to study biological systems with increasing precision, linking microscopic events to macroscopic outcomes.

Biophysics of Larger Systems

In addition to molecular and cellular investigations, biophysics extends to higher levels of organisation. Tissue biophysics explores mechanical properties, electrical conductivity and transport phenomena in complex biological media. At the organ level, biophysical models underpin the study of electrical conduction in neurons, mechanical behaviour of muscles and fluid dynamics of the cardiovascular and respiratory systems.
Neural biophysics, for example, investigates ion channel behaviour, membrane properties and network connectivity using a combination of electrophysiology, theoretical modelling and imaging. Similarly, population and ecosystem biophysics apply physical principles to understand spatial ecology, resource flow and collective behaviours in biological communities.
Medical physics, regarded as a branch of biophysics, applies physical principles to healthcare, including diagnostic imaging, radiation therapy, microscopy and nanomedical technologies. Theoretical proposals such as those put forward by Richard Feynman envision future applications of nanoscale biological machines in therapeutic contexts.

Historical Development

The origins of biophysics can be traced to early experimental efforts to quantify biological phenomena. Luigi Galvani’s eighteenth‐century investigations into bioelectricity provided foundational insights. During the mid‐nineteenth century, the Berlin school of physiologists, including Hermann von Helmholtz, Ernst Weber, Carl Ludwig and Johannes Müller, pioneered the integration of physical measurement and biological theory.
By the mid‐twentieth century, figures such as William Bovie contributed to technological advances, particularly in electrosurgery. The publication of Erwin Schrödinger’s What Is Life? in 1944 stimulated widespread interest by framing biological processes through the lens of physics.
The Biophysical Society, established in 1957, provided institutional support for the rapidly expanding field and continues to serve a global community of researchers. Alongside these developments, theoretical critiques, such as those of Robert Rosen, questioned the extent to which biophysical methods capture the full complexity of living systems, stimulating active debate about the discipline’s conceptual boundaries.

Biophysics within Academic Institutions

Although some universities maintain dedicated biophysics departments, many integrate biophysical research within broader departments including physics, chemistry, engineering, computer science, physiology and molecular biology. The focus within each institution often reflects the strengths of its contributing departments.
Examples of biophysical research areas span a wide spectrum:

• Molecular biology and biochemistry: gene regulation, protein dynamics, bioenergetics, virophysics
• Chemistry: nucleic acid structure, small‐molecule interactions, structure–activity relationships
• Computer science: molecular modelling, database design, neural network analysis
• Mathematics: dynamical systems, phylogenetics, quantitative modelling
• Physics: atomic‐scale imaging, structural determination, statistical mechanics
• Medicine and physiology: electrophysiology, membrane biology, fluid dynamics, radiation applications
• Neuroscience: membrane permittivity, brain slicing, neural network modelling

The breadth of this work highlights biophysics’ status as a methodological rather than purely disciplinary field, with approaches applied wherever physical laws govern biological behaviour.

Emerging Areas and Applications

New frontiers in biophysics include quantum biology, which explores quantum mechanical effects in biological systems such as photosynthetic energy transfer and molecular isomerisation. These studies have implications for the design of quantum computing architectures and biomimetic technologies.
Other emerging areas include nanotechnology, where biological molecules act as components of nanoscale devices, and bioelectronics, which integrates biological and electronic systems. Agricultural and environmental biophysics apply physical principles to crop modelling, soil dynamics and ecosystem monitoring.