Controlled release kinetics
Getting the right signal to the right place at the right time — for the right duration.
Growth factors are unstable and short-lived, so a bolus delivers a spike that is gone within hours while tissue formation takes weeks. Controlled release is the attempt to close that mismatch — and it is frequently the difference between a construct that works and one that does not.
The mechanisms are straightforward in principle: physical entrapment in a degrading matrix such as PLGA or a hydrogel, affinity binding that mimics how the ECM sequesters factors and releases them on demand, or covalent tethering. Each trades burst release against sustained delivery. Loading factors onto scaffolds by different strategies alters release kinetics and effective concentrations directly.
Two goals now dominate. Lower the total dose — the BMP-2 experience showed that supraphysiologic loading to compensate for short half-life carries real costs. And control sequence: VEGF before PDGF, recruitment before differentiation, reproducing the order native repair uses. See Growth factor delivery.
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