Thermal resilience of ensilicated lysozyme via calorimetric and in vivo analysis

Thermal Stabilisation of Lysozyme through Ensilication

Protein therapeutics, vaccines, and other commercial products are often sensitive to environmental factors, such as temperature and long-term storage. In many cases, long-term protein stability is achieved by refrigeration or freezing. One alternative is the encapsulation of the protein cargo within an inert silica matrix (ensilication) and storage or transport at room temperature as a dry powder. In this paper, we test the effect of three commonly used biological buffers on the ensilication, storage, and desilication of the enzyme lysozyme. We show that ensilication protects lysozyme from heat (100 °C for 1 h) and during storage (18 months at room temperature). The choice of ensilication buffer has little effect on the activity of lysozyme after desilication. Our results provide confidence in the continued pursuit of ensilication as a methodology for protein stabilisation and in its compatibility with biological buffers.

Protecting Proteins from Desiccation Stress Using Molecular Glasses and Gels

Faced with desiccation stress, many organisms deploy strategies to maintain the integrity of their cellular components. Amorphous glassy media composed of small molecular solutes or protein gels present general strategies for protecting against drying. We review these strategies and the proposed molecular mechanisms to explain protein protection in a vitreous matrix under conditions of low hydration. We also describe efforts to exploit similar strategies in technological applications for protecting proteins in dry or highly desiccated states. Finally, we outline open questions and possibilities for future explorations.

BMP2-Mediated Silica Deposition: An Effective Strategy for Bone Mineralization

The combined use of an osteogenic factor, such as bone morphogenetic protein 2 (BMP2), with a bone scaffold was quite functional for the reconstruction of bone defects. Although many studies using BMP2 have been done, there is still a need to develop an efficient way to apply BMP2 in the bone scaffold. Here, we reported an interesting fact that BMP2 has a silica deposition ability in the presence of silicic acid and proposed that such an ability of BMP2 can effectively immobilize and transport itself by a kind of coprecipitation of BMP2 with a silica matrix. The presence of BMP2 in the resulting silica was proved by SEM and EDS and was visualized by FITC-labeled BMP2. The delivery efficacy of BMP2 of silica-entrapped BMP2 on osteoblast differentiation and mineralization using MC3T3 E1 preosteoblast cells was evaluated in vitro. The coprecipitated BMP2 with silica exhibited osteogenesis at a low concentration that was insufficient to give an osteoinductive signal as the free form. Expectedly, the silica-entrapped BMP2 exhibited thermal stability over free BMP2. When applied to bone graft substitution, e.g., hydroxyapatite granules (HA), silica-entrapped BMP 2 laden HA (BMP2@Si/HA) showed sustained BMP2 release, whereas free BMP2 adsorbed HA by a simple dipping method (BMP2/HA) displayed a burst release of BMP2 at an initial time. In the rat critical-size calvarial defect model, BMP2@Si/HA showed better bone regeneration than BMP2/HA by about 10%. The BMP2/silica hybrid deposited on a carrier surface via BMP2-mediated silica precipitation demonstrated an increase in the loading efficiency, a decrease in the burst release of BMP2, and an increase in bone regeneration. Taken together, the coprecipitated BMP2 with a silica matrix has the advantages of not only being able to immobilize BMP2 efficiently without compromising its function but also serving as a stable carrier for BMP2 delivery.