1. Introduction

Lipid nanoparticles are spherical, nano-sized carriers (10-1000nm) composed of ionizable lipids (pH-sensitive, amphiphilic components), cholesterol, helper lipids, and PEGylated lipids that protect and deliver small therapeutic molecules into cells . These LNPs have become central in modern pharmaceuticals, having applications across mRNA and cancer vaccinations, gene editing (CRISPR-Cas9), protein replacement therapy, infectious disease treatments, and drug delivery in cosmetics and agriculture . 

1. Problem Statement

Despite the clinical promise of LNPs, the pharmaceutical manufacturing of them remains energy intensive, solvent-heavy, highly sensitive to process conditions, and challenging to scale-up, often making their production environmentally challenging at scale and inefficient (low-yielding) . In recent years, green synthesis approaches, including low-energy, solvent-minimised, bio-mediated, or mechanically driven routes, have been proposed as alternatives to chemical synthesis, as they offer vast financial, energetical and environmental benefits . Crucially, there is currently no integrated theoretical framework defining the minimum physical and chemical conditions required to produce nanoparticles that meet pharmaceutical quality standards, specifically biological compatibility, polydispersity, stability requirements, and batch-to-batch consistency.

As a result of this, green synthesis is often treated as an optimisation constraint rather than a design variable, limiting its integration into pharmaceutical production. This project aims to address this concern by developing a theoretical framework that formalises the threshold energy input (primary variable), transport regime, growth kinetics, and quality constraints.

This project treats biological and downstream considerations as fixed constraints rather than tunable parameters.

1. Research Aim and Objectives

The overall aim is to develop a theoretical framework that defines the minimum energy and process requirements for the low-energy manufacturing of pharmaceutically viable lipid

nanoparticles (LNPs), to maximise its potential employability and viability in LNP manufacturing processes.

Specific objectives include:

1. To define pharmaceutical quality constraints relevant to LNP manufacturing, including particle size, polydispersity, and stability.
2. To analyse LNP self-assembly through thermodynamic and kinetic principles, focusing on nucleation and growth behaviour.
3. To examine how different energy input modes influence LNP formation under low-energy (green) synthesis conditions.
4. To formalise threshold conditions under which pharmaceutically viable LNPs can theoretically be produced.
5. To map a design space linking energy input, mixing regime, and LNP quality outcomes.

1. Research Questions
2. What are the minimum thermodynamic and kinetic conditions required for LNP self-assembly that satisfies pharmaceutical quality constraints?
3. How do different energy input modes (thermal, mechanical, and chemical free energy) influence LNP formation efficiency?
4. To what extent can low-energy mixing and transport regimes support reproducible LNP manufacturing?
5. Can threshold requirements for pharmaceutically viable LNP production be formally defined from first-principles considerations?

1. Scope and Variables

Primary Variables:

- Energy input mode (thermal input, mechanical/shear energy, chemical free energy associated with solvent displacement)

- Mixing and transport regime (diffusion-limited vs convection-dominated mixing, residence time considerations)

- Nucleation and growth kinetics governing LNP self-assembly

Constraints (Outputs, Not Tuned Variables):

- Particle size range

- Polydispersity thresholds

- Colloidal stability requirements relevant to pharmaceutical manufacturing

The project intentionally excludes:

- Biological performance (cell uptake, toxicity)

- Drug encapsulation efficiency

- In vivo pharmacokinetics

- Regulatory policy and economic analysis

- Downstream formulation, storage, and distribution

1. Methodology

This project is set out to not require any laboratory work. The complete methodology is not yet known.

1. Tentative Timeline

1. Motivation and Significance

By formalising the minimum physical requirements for pharmaceutically viable LNP manufacturing, this project reframes green synthesis as a manufacturing design problem rather than a post-hoc optimisation. The framework developed can inform future low-energy, scalable nanoparticle manufacturing strategies and support more robust deployment of nanomedicine technologies.

From a leadership perspective, the project demonstrates how engineers can contribute to sustainable innovation by defining fundamental limits and design principles, enabling informed decision-making in pharmaceutical manufacturing.