Insulin Crystallization with pH and Salt Control for Uniform Crystal Size
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Solution Overview
Problem
The existing methods for preparing recombinant human insulin crystals face challenges in controlling impurities and achieving consistent crystal geometry and size at a preparative scale, leading to suboptimal performance in crystallization and freeze-drying stages.
Innovation Solution
A method involving the crystallization of recombinant human insulin in a solution containing zinc compounds and salts, adjusted to a pH of 4.8 to 5.2, with controlled addition rates and temperatures, followed by specific settling and freeze-drying procedures to achieve consistent crystal size and improved settling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional crystallization methods are used at preparative scale, then insulin crystals can be formed, but the crystal size and geometry are inconsistent and impurities are not effectively controlled
Solution Approach 1:
The patent applies parameter changes by precisely controlling pH (adjusted to 4.8-5.2 using acetic acid), temperature (maintained at 25±5°C during crystallization), and addition rates of zinc chloride and sodium chloride solutions. These controlled parameter changes enable consistent crystal nucleation and growth, resolving the contradiction between crystal size consistency and process reliability.
Solution Approach 2:
The patent employs preliminary action by pre-mixing zinc chloride and sodium chloride solutions in specific ratios before addition to the insulin solution. This pre-preparation ensures uniform distribution of crystallization agents and promotes consistent crystal formation, thereby improving both crystal geometry consistency and overall process reliability.
2Productivity
If crystallization is performed without optimized conditions, then the process can be completed, but sedimentation time is excessive and freeze-drying efficiency is reduced
Solution Approach 1:
The patent optimizes sedimentation time by controlling temperature (25±5°C during crystallization, followed by controlled cooling) and pH (4.8-5.2) parameters. These optimized parameters promote rapid and complete crystal settlement, reducing sedimentation time from traditional extended periods to just 12 hours while simultaneously improving freeze-drying efficiency through better crystal packing and reduced supernatant volume.
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 results in recombinant human insulin crystals with a consistent size of 15 μm-30 μm, reducing sedimentation time to 12 hours and improving the efficiency of freeze-drying by controlling impurities and ensuring robust process performance.
Implementation Method 1
In the presence of zinc, human insulin self-assembles into stable hexameric structures
Implementation Method 2
Recombinant Human Insulin crystallization occurs in two phases. The first phase is nucleation, the appearance of a crystalline phase from either a super cooled liquid or a supersaturated solvent. The second phase is crystal growth, which is the increase in the size of particles and leads to a crystalline state
Implementation Method 3
adjustment of the solution pH to near the isoelectric point of insulin (pH 5.5-6.0), which initiated crystal formation
Implementation Method 4
the time for centrifugation and freeze-drying is short
Data Source
AI summary
The present invention discloses a method for crystallizing recombinant Human Insulin at lab and manufacturing scale in the presence of zinc chloride and sodium chloride mixture, higher concentration of organic solvent (IPA-19 to 25 million) and adjusting the pH to 5.0 at a faster rate (≤5 minutes). The method further comprises adopting procedures wherein the settling time is reduced and the holding temperature is altered in order to facilitate consistent protein crystal formation between 15 μm-30 μm and to increase the robustness of the process.