PLGA Scaffold Porosity Control via Supercritical CO2 Foaming
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Solution Overview
Problem
Current methods for producing porous PLGA scaffolds with low inherent viscosity face challenges such as excessive expansion leading to loss of physical integrity and inadequate control over biologically active substance release, as well as inefficiencies in creating dual porosity structures using compressed gases or supercritical fluids.
Innovation Solution
A system comprising a biodegradable, porous, and homogeneous matrix with poly(D,L-lactic-co-glycolic acid) of inherent viscosity less than 0.5 dL/g, where a physical mixture of PLGA and a biologically active substance is processed with a compressed gas or supercritical fluid under controlled temperature and pressure conditions, followed by depressurization with cooling, to create a scaffold with controlled porosity and release properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If foaming with CO2 is used to prepare porous PLGA matrix with low inherent viscosity, then porosity is improved, but the scaffold loses physical and mechanical integrity due to excessive expansion
Solution Approach 1:
The patent applies parameter changes by precisely controlling foaming conditions including CO2 pressure (30-100 atm), temperature (20-40°C), and contact time (5 min - 24 h) to achieve controlled porosity (50-90%) while preventing excessive expansion that would compromise mechanical integrity of the low viscosity PLGA matrix
Solution Approach 2:
The patent implements dynamics by using a controlled depressurization process after supercritical CO2 foaming, where pressure is gradually reduced to allow controlled pore formation and expansion, enabling the matrix to achieve desired porosity without uncontrolled expansion that would destroy structural integrity
2Duration of action of stationary object
If PLGA with low inherent viscosity is used, then degradation time is improved to match bone regeneration rate, but the ability to control release of biologically active substances deteriorates
Solution Approach 1:
The patent applies local quality by creating a heterogeneous porous structure with different pore sizes (micro pores from foaming and macro pores from leaching) within the PLGA matrix, where different regions provide different release kinetics, enabling controlled release of biologically active substances while maintaining overall degradation time of 8-10 weeks
Solution Approach 2:
The patent uses composite materials by combining PLGA with hydroxyapatite (HA) to create a PLGA/HA composite scaffold, where HA provides structural support and controlled release properties while PLGA provides biodegradability, achieving both rapid degradation for bone regeneration and controlled release of active substances
3Volume of stationary object
If water-soluble particles are incorporated to create dual porosity scaffolds, then macropores are improved, but processing time increases due to additional drying stage and active substances are lost during washing
Solution Approach 1:
The patent merges multiple porosity creation mechanisms by combining supercritical CO2 foaming (creating micro pores) with thermal decomposition of porogenic agents like ammonium bicarbonate (creating macro pores), achieving dual porosity in a single integrated process without separate drying or washing stages, thereby reducing processing time and preventing loss of active substances
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 method produces scaffolds with a porosity greater than 50% and controlled release of biologically active substances, suitable for regenerative medicine, maintaining mechanical integrity and facilitating tissue regeneration without the need for additional drying stages or organic solvents.
Implementation Method 1
preparing a physical mixture comprising poly(D,L-lactic-co-glycolic acid) and a biologically active substance and, optionally a porogenic agent; placing the said mixture in contact with a compressed gas or supercritical fluid
Implementation Method 2
placing the said mixture in contact with a compressed gas or supercritical fluid at a pressure between 40 and 120 bar and a temperature between 20 and 40° C.
Implementation Method 3
depressurization at a rate between 2 and 8 bar/min with cooling through the addition of a compressed liquid at a temperature between −196 and 19° C.
Implementation Method 4
Alternatively, a porogenic agent is incorporated to form macropores by thermal decomposition
Implementation Method 5
depressurization at a rate between 2 and 8 bar/min with cooling through the addition of a compressed liquid at a temperature between −196 and 19° C.
Data Source
AI summary
A system for administering biologically active substances produced by foaming techniques using compressed gases or supercritical fluids relates to a porous system containing biologically active substances. The system includes a polymer matrix of poly(D,L-lactic-co-glycolic acid) or a polymer mixture containing poly(D,L-lactic-co-glycolic acid) of an intrinsic viscosity of less than 0.5 dL/g with other biodegradable synthetic or semisynthetic polyesters, a release-regulating component (starch and derivatives), and at least one biologically active substance. The matrix is biodegradable with a solid or semisolid consistency and a homogeneous appearance. A method for producing these systems using foaming with compressed fluids, and the use for the production of implants and scaffolds having this system are also disclosed. Optionally, a porogenic agent can be used for the formation of macropores by thermal decomposition.