Chitosan–Dextran Sulfate Nanoparticles for Stable LDL Reduction

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Solution Overview

Problem

Current therapies for atherosclerosis are ineffective, and existing nanoparticle formulations for LDL cholesterol reduction and macrophage oxLDL uptake inhibition are prone to aggregation and size instability, limiting their therapeutic efficacy.

Innovation Solution

Development of nanoparticles with controlled hydrodynamic diameters (10-400 nm) and specific charge ratios, composed of positively and anionically charged polymers, such as chitosan and gelatin, to inhibit foam cell formation and induce cholesterol efflux.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If nanoparticles are formed with small size (less than 200 nm) to prolong circulation time, then circulation retention is improved, but aggregation occurs after centrifugation leading to size instability

Engineering Contradiction:

Improvecirculation retention timeVSAvoidnanoparticle size stability

Core Design Contradiction:

Duration of action of stationary objectVSStability of the object's composition

Solution Approach 1:

The patent applies parameter changes by precisely controlling the molecular weight ratios of chitosan and dextran sulfate, adjusting pH levels, and optimizing ionic strength to prevent nanoparticle aggregation while maintaining small size (10-200 nm) for prolonged circulation. The formulation specifies chitosan molecular weight of 10,000-1,000,000 Da and dextran sulfate molecular weight of 1,000-10,000 Da with specific weight ratios to stabilize nanoparticle size.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining chitosan (positively charged polysaccharide) with dextran sulfate (negatively charged polysaccharide) to form polyelectrolyte complex nanoparticles. This composite structure leverages electrostatic interactions between oppositely charged polymers to create stable nanoparticles that resist aggregation while maintaining optimal size for circulation.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If dextran sulfate and chitosan are combined in excessive ratios to form stable PEC, then nanoparticle stability is improved, but particle size increases beyond 200 nm reducing circulation retention

Engineering Contradiction:

Improvenanoparticle stabilityVSAvoidcirculation retention time

Core Design Contradiction:

Stability of the object's compositionVSDuration of action of stationary object

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If conventional nanoparticle formulations are used to reduce LDL cholesterol, then LDL binding is achieved, but foam cell formation is not effectively inhibited

Engineering Contradiction:

ImproveLDL cholesterol reductionVSAvoidfoam cell inhibition efficacy

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies universality by designing nanoparticles with dual functionality: (1) binding to LDL cholesterol through electrostatic interactions between positively charged chitosan and negatively charged LDL, and (2) inhibiting foam cell formation through uptake by macrophages and induction of cholesterol efflux. This multi-functional approach addresses both LDL reduction and foam cell inhibition simultaneously.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent applies self-service by utilizing the natural properties of the nanoparticle components to achieve therapeutic effects. The positively charged chitosan automatically binds to negatively charged LDL, and the nanoparticles are naturally taken up by macrophages via scavenger receptors, inducing cholesterol efflux without requiring external intervention or additional therapeutic agents.

Inventive Principle:

Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The nanoparticles effectively reduce LDL cholesterol levels, inhibit oxLDL uptake by macrophages, and induce cholesterol efflux, and induce cholesterol efflux, and induce cholesterol efflux.

Implementation Method 1

CH is a natural biocompatible polysaccharide with abundant amine groups that can form strong electrostatic interactions with the sulfate groups on DS. The strong electrostatic interactions between the two polymers enables the formation stable insoluble PEC of various sizes.

Methodology Applied

Scientific EffectElectrostatic interaction: Electrostatics

Implementation Method 2

Dextran sulfate (DS) is a biocompatible and biodegradable polysaccharide that is highly negatively charged due to its numerous sulfate groups, which can selectively bind to the positively charged apolipoprotein B molecule in LDL.

Methodology Applied

Scientific EffectElectrostatic attraction: Electrostatics

Implementation Method 3

The modified LDL (oxLDL) particles are endocytosed by macrophages via scavenger receptors. In addition, it can bind to scavenger receptor A (SR-A). This property can potentially be used to inhibit oxLDL uptake by macrophages.

Methodology Applied

Scientific EffectReceptor-mediated endocytosis: