The invention relates to a suspension of delivery particles (PV) of active principles (AP), in particular proteins. These PV are based on a diblock copolymer consisting of a block polymer of hydroxycarboxylic acid Alpha (CHAP) hydrophobic neutral and a polyamino acid block (s) Linear (s) hydrophilic (s) to peptide alpha sequence polyAAI ionized at least in part. These CHAP / polyAAI PV can be obtained spontaneously in the absence of surfactant and be stable. These PV are capable of combining in colloidal suspension in the undissolved state with at least one AP and to release the latter delayed or sustained manner. The invention also provides a powdery solid from which are derived the PV, and the preparation of this solid and the PV suspension.