Nanotechnology: From In‑Vivo Imaging Systems to Controlled Drug Delivery

Abstract

Nanotechnology is reshaping biomedicine by enabling unprecedented precision in imaging and drug delivery. Recent innovations—radionuclide probes, quantum‑dot fluorophores, magnetic nanoparticles, and gold‑nanoparticle biosensors—have markedly improved the detection and treatment of cancer and other diseases. This review focuses on two core domains of nanomedicine— in vivo imaging and targeted drug delivery—summarizing the latest advances and charting future research pathways.

Review

Introduction

Nanotechnology, the study and manipulation of matter at the 1–100 nm scale, is driving transformative changes across engineering and life sciences. By engineering functional materials and devices at the atomic level, researchers can create systems that interact directly with cells and biomolecules. The concept, first articulated by Feynman in the 1950s and later expanded by Drexler, Freitas, and others, envisioned nanorobots repairing tissues at the molecular level. Since the launch of the National Nanotechnology Initiative in 2000, investments—US $3.7 billion, EU €1.2 billion, Japan ¥750 million—have accelerated advances in nanophotonics, nanoelectronics, and biophysical modeling, paving the way for medical nanodevices.

Pharmaceutical Nanosystems

Pharmaceutical nanotechnology is broadly divided into nanomaterials and nanodevices. Nanomaterials—polymeric, non‑polymeric, zero‑, one‑, two‑, or three‑dimensional—include nanoparticles, micelles, dendrimers, quantum dots, and metallic cores. Nanodevices comprise MEMS/NEMS, microarrays, and respirocytes, each engineered to interface with biological systems at the molecular level, enabling unprecedented diagnostic and therapeutic precision.

Manufacturing Approaches

Bottom‑up strategies (inverse micelles, CVD, sol‑gel, self‑assembly) build structures from the molecular level, while top‑down methods (milling, vapor deposition, lithography) sculpt pre‑existing materials into nanoscale features. Hybrid approaches combine both, offering versatility in particle size, shape, and surface functionality. These manufacturing routes are summarized in Table 2.

Biomedical Applications of Advanced Nanotechnology

Imaging

Nanoparticles sized 10–100 nm serve as carriers for molecular‑level modifications, enabling site‑specific imaging of cancer cells. Recent advances include radionuclide probes, quantum dots, magnetic nanoparticles, and gold‑nanoparticle‑based biosensors, which together enhance diagnostic accuracy and therapeutic targeting.

Radionuclide Imaging

Radionuclide imaging tracks radiolabeled biomarkers in vivo, overcoming the limitations of small‑molecule contrast agents. PET imaging of multidrug resistance, for example, uses 99mTc‑tetrofosmin and sestamibi to probe P‑glycoprotein activity in tumors [32, 33]. Nanocarriers such as liposomes and dendrimers enable high‑capacity loading of radionuclides, improving signal‑to‑noise ratios.

Quantum Dots

Semiconductor quantum dots, with size‑dependent fluorescence, offer superior brightness, photostability, and tunable spectra compared to conventional dyes. Core–shell designs (e.g., CdSe/ZnS) provide chemical stability, while surface ligands enable specific targeting. Recent work demonstrates quantum‑dot conjugates for prostate cancer imaging in mice [42] and reduces toxicity by employing cadmium‑free cores (CuInS₂/ZnS) that are excreted efficiently when <5.5 nm in diameter [45, 46].

Biosensors

Gold‑nanoparticle‑modified electrodes (e.g., glassy‑carbon electrodes) significantly enhance immobilization of antibodies or enzymes, boosting sensitivity for biomarkers such as human chorionic gonadotropin [54, 55]. Carbon nanotubes and magnetic nanoparticles also contribute high surface area and unique electronic or magnetic properties, expanding biosensor applications to DNA detection, protein assays, and environmental monitoring [60‑70].

Magnetic Nanoparticles

Superparamagnetic iron oxides (SPIOs) and ultra‑small SPIOs (USPIOs) serve as MRI contrast agents and drug carriers. They enable imaging of liver tumors as small as 2–3 mm and lymph node metastases of 5–10 mm, supporting early staging and treatment planning in breast, colon, and prostate cancers [70‑73].

Drug Delivery

Nanoparticle‑based drug delivery platforms—liposomes, solid lipid nanoparticles, dendrimers, and metal‑containing nanoparticles—overcome pharmacokinetic limitations of conventional formulations, achieving >75 % of nanomedicine sales [74]. They enhance bioavailability, reduce systemic toxicity, and allow controlled release.

Ophthalmology

Ocular delivery remains challenging due to the eye’s complex barriers. Nanocarriers such as PLGA nanoparticles, chitosan‑gelatin particles, and dendrimer assemblies improve corneal penetration, extend residence time, and provide sustained release of anti‑inflammatory, anti‑infective, and anti‑glaucoma agents [80‑86]. For instance, PLGA nanoparticles loaded with pranoprofen in a hydrogel demonstrate superior rheology and patient compliance [80].

Pulmonology

Lung diseases—including COPD, lung cancer, and tuberculosis—benefit from inhalable nanoparticles that deliver therapeutics directly to the target site. PLGA and gelatin nanoparticles, Janus particles, and PAMAM dendrimers have shown enhanced deposition, reduced cytotoxicity, and improved therapeutic outcomes in preclinical models [90‑97]. Engineered metal and polymeric nanoparticles further support vaccine delivery and modulation of pulmonary immune homeostasis [96‑97].

Cardiovascular System

Cardiovascular disease remains the leading cause of morbidity worldwide, with >9 million deaths annually [99‑100]. Nanocarriers—such as chitosan‑liposomes for sirolimus, PLGA nanoparticles for platelet‑derived growth factor blockers, and polymeric particles for VEGF delivery—offer targeted therapy for restenosis, myocardial ischemia, and heart failure, improving functional outcomes in animal models [102‑106].

Oncology

Nanomedicine enhances the therapeutic index of chemotherapeutics by exploiting the enhanced permeability and retention (EPR) effect and active targeting strategies (ligand grafting, stimuli‑responsive carriers). Biodegradable nanocarriers loaded with tamoxifen, doxorubicin, cisplatin, oxaliplatin, or 5‑fluorouracil achieve sustained release, higher tumor accumulation, and reduced systemic toxicity, as demonstrated in breast, lung, and colorectal cancer models [126‑129].

Conclusions

Nanotechnology has accelerated the development of highly specific imaging agents and precision drug delivery systems, particularly for oncology, ophthalmology, pulmonology, and cardiovascular medicine. The ability to track nanomaterials in real time, combined with scalable manufacturing techniques, has paved the way for clinical translation. Nonetheless, challenges remain in large‑scale production, regulatory oversight, and long‑term safety. Continued interdisciplinary research will be essential to fully realize the therapeutic potential of nanomedicine.

Abbreviations

AIE:

Aggregation‑induced emission

BDP:

Beclometasone dipropionate

BODIPY:

Boron dipyrromethane

CNTs:

Carbon nanotubes

COPD:

Chronic obstructive pulmonary disease

CulnS₂/ZnS:

Copper indium sulfide/zinc sulfide quantum dots

CVD:

Chemical vapor deposition

DNA:

Deoxyribonucleic acid

ENPs:

Engineered nanoparticles

EPR:

Enhanced permeability and retention

GCE:

Glassy carbon electrode

GNPs:

Gold nanoparticles

GQD:

Grapheme quantum dots

HCG:

Human chorionic gonadotrophin

MEMS:

Microelectromechanical systems

MI:

Myocardial ischemia

MNPs:

Magnetic nanoparticles

MSNs:

Mesoporous silica nanoparticles

MWNT:

Multi‑walled carbon nanotubes

NEMS:

Nanoelectromechanical system

PAH:

Pulmonary arterial hypertension

PCL:

Poly caprolactone

PDGF:

Platelet‑derived growth factors

PEG:

Polyethylene glycol

PET:

Positron emission tomography

PLGA:

Poly lactic‑co‑glycolic acid

ROS:

Reactive oxygen species

SiRNA:

Short interference RNA

SLNS:

Solid lipid nanoparticles

SPIOs:

Superparamagnetic iron oxides

VEGF:

Vascular endothelial growth factor