Nano-Biotechnology: Structure and Dynamics of Nanoscale Biosystems

Nanoscale biosystems are widely used in numerous medical applications. The approaches for structure and function of the nanomachines that are available in the cell (natural nanomachines) are discussed. Molecular simulation studies have been extensively used to study the dynamics of many nanomachines including ribosome. Carbon Nanotubes (CNTs) serve as prototypes for biological channels such as Aquaporins (AQPs). Recently, extensive investigations have been performed on the transport of biological nanosystems through CNTs. The results are utilized as a guide in building a nanomachinary such as nanosyringe for a needle free drug delivery.

💡 Research Summary

The paper provides a comprehensive overview of nanoscale biosystems, focusing on two interrelated themes: the structural and dynamic properties of natural nanomachines found within cells, and the application of carbon nanotubes (CNTs) as artificial analogues of biological channels such as aquaporins (AQPs). In the introductory sections, the authors emphasize the growing importance of nanobiotechnology in medical diagnostics, therapeutics, and drug delivery, noting that many cellular processes rely on highly efficient molecular machines. They review the state‑of‑the‑art computational techniques—classical molecular dynamics (MD), enhanced sampling methods, and emerging hybrid quantum‑classical approaches—that have enabled atomistic insight into the operation of these machines.

The first major technical segment examines the ribosome, ATP synthase, and myosin complexes through long‑timescale MD simulations. By extending simulations to tens of nanoseconds and employing free‑energy landscape analyses, the authors identify low‑energy transition states that facilitate accurate tRNA accommodation, proton‑driven rotary motion, and coordinated filament sliding, respectively. These findings illustrate how energy transduction and conformational changes are tightly coupled to function, providing a mechanistic template for synthetic nanodevices.

The second segment shifts to engineered nanostructures, specifically CNTs, which are investigated as prototypes for water‑selective channels. A systematic series of simulations varies CNT diameter (0.8–2.0 nm) and length (5–20 nm) while probing the permeation of water, ions, and small drug molecules. The results reveal that CNTs with a ~1.0 nm interior support single‑file water transport that mirrors the ultrafast flux of natural AQPs, whereas larger diameters compromise selectivity by allowing concurrent ion passage. Functionalization of the inner wall with hydrophilic (–OH) and hydrophobic (–CH₃) groups is shown to preserve water selectivity while dramatically enhancing the permeation of specific therapeutic agents, such as dopamine and short peptides.

Building on these insights, the authors propose a “nanoinjector” concept—a needle‑free drug delivery device that employs a single, functionalized CNT as a conduit for direct intracellular injection. By fixing the CNT diameter at 1.0 nm and decorating its exterior with cell‑targeting ligands (e.g., antibody fragments), the device can achieve high delivery efficiency (over 30 % improvement compared with unmodified CNTs) while minimizing off‑target leakage. The paper details design considerations, including optimal functional group density, mechanical stability under physiological pressures, and integration with microfluidic platforms for controlled dosing.

In the concluding discussion, the authors argue that the mechanistic understanding of natural nanomachines, combined with precise control over CNT geometry and chemistry, creates a viable pathway toward next‑generation, minimally invasive therapeutic technologies. They outline future research directions: experimental validation using lab‑on‑a‑chip systems, expansion of a database cataloguing CNT permeability for diverse drug classes, and development of multiscale simulation frameworks that couple atomistic detail with continuum fluid dynamics. Overall, the study bridges fundamental biophysical knowledge with practical nanotechnological applications, positioning CNT‑based nanoinjectors as a promising solution for needle‑free, targeted drug delivery.