Genetic Engineering of Silaffin-Like Peptides for Binding and Precipitating Siliceous Materials

Biomimetic and bioinspired silicifications: Recent advances for biomaterial design and applications

The rational design and controllable synthesis of functional silica-based materials have gained increased interest in a variety of biomedical and biotechnological applications due to their unique properties. The current review shows that marine organisms, such as siliceous sponges and diatoms, could be the inspiration for the fabrication of advanced biohybrid materials. Several biomolecules were involved in the molecular mechanism of biosilicification in vivo. Mimicking their behavior, functional silica-based biomaterials have been generated via biomimetic and bioinspired silicification in vitro. Additionally, several advanced technologies were developed for in vitro and in vivo immobilization of biomolecules with potential applications in biocatalysis, biosensors, bioimaging, and immunoassays. A thin silica layer could coat a single living cell or virus as a protective shell offering new opportunities in biotechnology and nanomedicine fields. Promising nanotechnologies have been developed for drug encapsulation and delivery in a targeted and controlled manner, in particular for poorly soluble hydrophobic drugs. Moreover, biomimetic silica, as a morphogenetically active biocompatible material, has been utilized in the field of bone regeneration and in the development of biomedical implantable devices. STATEMENT OF SIGNIFICANCE: In nature, silica-based biomaterials, such as diatom frustules and sponge spicules, with high mechanical and physical properties were created under biocompatible conditions. The fundamental knowledge underlying the molecular mechanisms of biosilica formation could inspire engineers and chemists to design novel hybrid biomaterials using molecular biomimetic strategies. The production of such biohybrid materials brings the biosilicification field closer to practical applications. This review starts with the biosilicification process of sponges and diatoms with recently updated researches. Then, this article covers recent advances in the design of silica-based biomaterials and their potential applications in the fields of biotechnology and nanomedicine, highlighting several promising technologies for encapsulation of functional proteins and living cells, drug delivery and the preparation of scaffolds for bone regeneration.

Self-encapsulation and controlled release of recombinant proteins using novel silica-forming peptides as fusion linkers

Recently, the potential use of biomimetic silica as smart matrices for the auto-encapsulation and controlled release of functional proteins has gained increased interest because of the mild synthesis conditions. Inspired by biological silicification, in this study, we studied novel silica-forming peptides (SFPs), Volp1 and Salp1, to mediate the generation of silica hybrids in vitro. The fusion of SFPs to model fluorescent proteins directed their auto-encapsulation in wet sol-gel silica materials. Furthermore, the SFPs served as affinity linkers for the immobilization of recombinant proteins in silica. Interestingly, the SFP fusion proteins modulated silicic acid polycondensation and allowed for the self-immobilization of SFP fusion proteins in two distinct silica formulations depending on the ionic strength-precipitated silica particles or wet silica gel. The controlled release of Salp1/Volp1 fusion proteins from silica matrices was significantly greater than that of the silaffin R5 fusion proteins. Subsequently, we showed that multiple SFP-tagged proteins homogenously entrapped within a silica matrix could be separately released following pre-incubation with different concentrations of l-arginine solution. These new findings provide a simple and reproducible route for silica hybrid formation for in situ stable auto-encapsulation and the sustained release of recombinant proteins with potential applications in biotechnology.

Spatial-temporal profiling of prodiginines and serratamolides produced by endophytic Serratia marcescens harbored in Maytenus serrata

An endophytic bacterium, Serratia marcescens MSRBB2, isolated from inner bark of a Cameroonian Maytenus serrata plant, was subjected to the OSMAC (One Strain Many Compounds) approach and metabolic profiling using HPLC-HRMSⁿ. We identified 7 prodiginines along with 26 serratamolides. Their biosynthetic pathways were elucidated by feeding with labeled precursors in combination with HRMSⁿ. Dual-culture confrontation/restriction assays of the bacterial endophyte were devised with coexisting fungal endophytes (Pestalotiopsis virgatula, Aspergillus caesiellus and Pichia spp.) as well as with unrelated, non-endophytic fungi belonging to the same genera. The assays were combined with scanning electron microscopy (SEM) as well as matrix-assisted laser desorption ionization imaging high-resolution mass spectrometry (MALDI-imaging-HRMS) for visualizing, both in high spatial and temporal resolution, the distribution and interplay of the compounds during microbial interactions. We demonstrated the effect of prodigiosin produced by endophytic S. marcescens MSRBB2 as an allelochemical that specifically inhibits coexisting endophytic fungi. Our results provide new insights into the physiological and ecological relevance of prodiginines and serratamolides within the context of allelopathy and chemical defense interaction occurring between coexisting endophytes harbored in M. serrata.