Nanomedicine, Nano-Energy & Nanosafety

Nanotechnology at work — responsibly. Learn nanomedicine (lipid nanoparticles for mRNA, liposomal drugs like Doxil, the EPR effect and active targeting, controlled release kinetics — Higuchi and first order, theranostics, photothermal therapy, nano-diagnostics), nano-energy (battery nanomaterials, catalysts, perovskite and QD solar cells, hydrogen), environmental nano (water filtration, photocatalysis, sensors), nanosafety and toxicology (surface-area dose, inhalation, biodistribution), regulation, life-cycle and ethics — with Python for drug release profiles and surface-area dose.

Nanotechnology has moved from labs into medicines, batteries, catalysts, sunscreens and water filters. COVID-19 mRNA vaccines, delivered by lipid nanoparticles, reached billions of people — a landmark for nanomedicine.

The same properties that make nanomaterials useful — small size, high reactivity, ability to cross barriers — can create health and environmental risks, so safety-by-design is integral to nano engineering.

An analogy

A drug nanocarrier is like a delivery van with a GPS and a locked door: it protects the parcel (drug) on the road (bloodstream), navigates to the right address (tumour or cell), and opens only on arrival (triggered release).

Nanomedicine

Key applications:

• Drug delivery — liposomes (Doxil), lipid nanoparticles (mRNA vaccines, siRNA), polymeric nanoparticles, albumin-bound paclitaxel
• Targeting — passive (EPR in leaky tumour vessels) and active (antibodies, ligands); stealth PEG coatings
• Diagnostics — gold nanoparticle rapid tests, quantum-dot and magnetic imaging, biosensors
• Therapy — photothermal (gold nanoshells), magnetic hyperthermia, radiosensitisers
• Theranostics — combined diagnosis and therapy

Energy and environment

Batteries: nanostructured silicon anodes, LFP and NMC nanoparticles, CNT conductive additives; catalysts: Pt nanoparticles in fuel cells, single-atom catalysts; solar: perovskite nanocrystals, quantum-dot and dye-sensitised cells, anti-reflective nanotextures; hydrogen: nanostructured electrocatalysts. Environment: nanofiltration and graphene-oxide membranes, TiO₂ photocatalysis, nano zero-valent iron for groundwater remediation, nano-enabled gas and water sensors.

Nanotoxicology

Risk = hazard × exposure. Nanoparticles can be inhaled deep into lungs, cross some biological barriers, generate reactive oxygen species and accumulate in liver/spleen. Toxicity depends on size, shape (long rigid fibres resemble asbestos), surface chemistry, charge, solubility and agglomeration. Dose metrics: mass, number and surface area. In-vitro, in-vivo and in-silico (nano-QSAR) methods assess hazard.

Regulation, safe-by-design and ethics

Regulators (FDA, EMA, CDSCO, EU REACH nano annexes) require nano-specific characterisation (size distribution, surface properties) and safety data. Occupational controls: enclosures, local exhaust ventilation, HEPA filtration, respirators. Safe-by-design modifies materials (coatings, dissolution, shape) to reduce hazard while keeping function. Life-cycle assessment covers production energy and end-of-life release. Ethical issues: equitable access, privacy with nano-sensors, dual use and public engagement.

Formulas

• Higuchi release: Q(t) = k_H·√t
• First-order release: Q(t) = Q∞(1 − e^(−kt))
• Korsmeyer–Peppas: M_t/M_∞ = k·tⁿ (n reveals mechanism)
• Surface-area dose: dose (cm²) = mass × 6/(ρd)
• Photocatalysis (first order): C = C₀e^(−k_app t)

Worked example: Higuchi time

Given: k_H = 20 %/√h

Find: Time for 80% release.

• (80/20)²

Answer: 16 h

Worked example: Surface-area dose

Given: 5 mg of 50 nm silica (ρ 2200)

Find: Surface area.

• 6/(2200 × 50e−9) = 54.5 m²/g
• × 0.005 g

Answer: 0.27 m²

Worked example: Photocatalysis

Given: k_app = 0.05 min⁻¹

Find: Time to 90% dye removal.

• ln 10/0.05

Answer: 46 min

Drug release and surface-area dose

import math
# Nanomedicine: Higuchi drug release and dose by surface area; plasmonic gold colour
for t_h in (1, 4, 9, 16, 24):
    released = min(100.0, 18.0 * math.sqrt(t_h))     # % released, Higuchi constant 18 %/sqrt(h)
    print(f"t = {t_h:2d} h: {released:5.1f}% released")
print(f"time to 90% release: {(90/18)**2:.1f} h")
# Same mass (1 mg TiO2, density 4230) as 20 nm vs 200 nm particles: total surface area
for d_nm in (20, 200):
    ssa = 6 / (4230 * d_nm * 1e-9)          # m2/kg
    print(f"{d_nm:3d} nm particles: {ssa*1e-6*1e4:.1f} cm2 per mg")
# t =  1 h:  18.0% released
# t =  4 h:  36.0% released
# t =  9 h:  54.0% released
# t = 16 h:  72.0% released
# t = 24 h:  88.2% released
# time to 90% release: 25.0 h
#  20 nm particles: 709.2 cm2 per mg
# 200 nm particles: 70.9 cm2 per mg

Diffusion-controlled (Higuchi) release gives a fast start and slowing tail — about 90% in a day for this carrier. For safety, the same mass of 20 nm particles presents 10× more surface area than 200 nm ones; toxicological responses (e.g. lung inflammation) often scale with surface area rather than mass, so nano dose metrics must be chosen carefully.

Common mistakes

• Wrong: Over-relying on the EPR effect. — Right: EPR is heterogeneous in human tumours; few % of dose reaches them.
• Wrong: Reporting only mass dose for nano-toxicity. — Right: Include size, surface area and number.
• Wrong: Handling nanopowders on open benches. — Right: Use enclosures, LEV and appropriate PPE.

Applications

• Vaccines & gene therapy: LNP delivery of mRNA and siRNA.
• Cancer therapy: Liposomal and albumin nanoparticle drugs.
• Clean energy: Nano-catalysts and battery materials.
• Occupational safety: Exposure control in nano-manufacturing.

Key takeaways

• Nanocarriers protect, target and release drugs.
• Nano transforms batteries, catalysts, solar, water.
• Toxicity depends on size, shape, surface — use surface-area dose.
• Safe-by-design, regulation and ethics are essential.

Going further

• Protein corona: How serum proteins change nanoparticle identity.
• Single-atom catalysts: Maximum metal efficiency.
• Nano-QSAR: Computational prediction of nanotoxicity.