Search results for "Note"

Poly(sarcosine) surface modification imparts stealth-like properties to liposomes

2019

Circulation lifetime is a crucial parameter for a successful therapy with nanoparticles. Reduction and alteration of opsonization profiles by surface modification of nanoparticles is the main strategy to achieve this objective. In clinical settings, PEGylation is the most relevant strategy to enhance blood circulation, yet it has drawbacks, including hypersensitivity reactions in some patients treated with PEGylated nanoparticles, which fuel the search for alternative strategies. In this work, lipopolysarcosine derivatives (BA-pSar, bisalkyl polysarcosine) with precise chain lengths and low polydispersity indices are synthesized, characterized, and incorporated into the bilayer of preformed…

Porous biomaterials and scaffolds for tissue engineering

2019

In the present article, an overview of the definition of tissue engineering and scaffold requirements is reported. In particular, scaffold porosity and its relevance for several tissue target regeneration is highlighted. Different scaffold fabrication techniques are reported and explained in details, highlighting advantages and disadvantages for all of these techniques, regarding the specific final applications.

Isolation of the silicatein-α interactor silintaphin-2 by a novel solid-phase pull-down assay.

2011

The skeleton of siliceous sponges consists of amorphous biogenous silica (biosilica). Biosilica formation is driven enzymatically by means of silicatein(s). During this unique process of enzymatic polycondensation, skeletal elements (spicules) that enfold a central proteinaceous structure (axial filament), mainly comprising silicatein, are formed. However, only the concerted action of silicatein and other proteins can explain the genetically controlled diversity of spicular morphotypes, from simple rods with pointed ends to intricate structures with up to six rays. With the scaffold protein silintaphin-1, a first silicatein interactor that facilitates the formation of the axial filament and…

Morphology of Sponge Spicules: Silicatein a Structural Protein for Bio-Silica Formation

2010

Most forms of multicellular life have developed a calcium-based skeleton, while only a few specialized organisms complement their body plan with silica, such as sponges (phylum Porifera). However, the way in which sponges synthesize their silica is exceptional. They use an enzyme, silicatein, for the polymerization/polycondensation of silica, and thereby form their highly resistant and stabile massive siliceous skeletal elements (spicules). During this biomineralization process (i.e., biosilicification), hydrated amorphous silica is deposited within highly specialized sponge cells, ultimately resulting in structures that range in size from micrometers to meters. This peculiar phenomenon has…

Evidence for synergistic and complementary roles of Bassoon and darkness in organizing the ribbon synapse

2012

Abstract Ribbon synapses are tonically active high-throughput synapses. The performance of the ribbon synapse is accomplished by a specialization of the cytomatrix at the active zone (CAZ) referred to as the synaptic ribbon (SR). Progress in our understanding of the structure–function relationship at the ribbon synapse has come from observations that, in photoreceptors lacking a full-size scaffolding protein Bassoon ( Bsn Δ Ex 4 / 5 ), dissociation of SRs coincides with perturbed signal transfer. The aim of the present study has been to elaborate the role of Bassoon as a structural organizer of the ribbon synapse and to differentiate it with regard to the ambient lighting conditions. The ul…

2020

In Bone Tissue Engineering (BTE), autologous bone-regenerative cells are combined with a scaffold for large bone defect treatment (LBDT). Microporous, polylactic acid (PLA) scaffolds showed good healing results in small animals. However, transfer to large animal models is not easily achieved simply by upscaling the design. Increasing diffusion distances have a negative impact on cell survival and nutrition supply, leading to cell death and ultimately implant failure. Here, a novel scaffold architecture was designed to meet all requirements for an advanced bone substitute. Biofunctional, porous subunits in a load-bearing, compression-resistant frame structure characterize this approach. An o…

Biosilica-loaded poly(ϵ-caprolactone) nanofibers mats provide a morphogenetically active surface scaffold for the growth and mineralization of the os…

2014

Bioprinting/3D cell printing procedures for the preparation of scaffolds/implants have the potential to revolutionize regenerative medicine. Besides biocompatibility and biodegradability, the hardness of the scaffold material is of critical importance to allow sufficient mechanical protection and, to the same extent, allow migration, cell–cell, and cell–substrate contact formation of the matrix-embedded cells. In the present study, we present a strategy to encase a bioprinted, cell-containing, and soft scaffold with an electrospun mat. The electrospun poly(e-caprolactone) (PCL) nanofibers mats, containing tetraethyl orthosilicate (TEOS), were subsequently incubated with silicatein. Silicate…

The use of hydrogels in bone-tissue engineering

2010

Many different types of scaffold materials have been used for tissue engineering applications, and hydrogels form one group of materials that have been used in a wide variety of applications. Hydrogels are hydrophilic polymer networks and they represent an important class of biomaterials in biotechnology and medicine because many hydrogels exhibit excellent biocompatibility with minimal inflammatory responses and tissue damage. Many studies have demonstrated the use of hydrogels in bone-tissue engineering applications. In this report, the summary was conducted on various kinds of polymers and different modification methods of hydrogels to enhance bone formation. The results revealed that hy…

Cell culture models of higher complexity in tissue engineering and regenerative medicine.

2007

Cell culture techniques have tended to be used in biomaterial research as a screening method prior to embarking on specific in vivo experimentation. This presentation aims at showing that it is possible to develop more sophisticated in vitro systems using primary human cells in co-culture with other cell types and biomaterials in a three-dimensional setting. While the predictive value of such systems is still not proven these models can be employed to unravel the complexity of biological systems in order to understand molecular mechanisms of cell-cell and cell-material interactions. The brief overview is under the headings of basic principles of relevant culture systems, the study of inflam…

The Deep-Sea Natural Products, Biogenic Polyphosphate (Bio-PolyP) and Biogenic Silica (Bio-Silica), as Biomimetic Scaffolds for Bone Tissue Engineeri…

2013

Bone defects in human, caused by fractures/nonunions or trauma, gain increasing impact and have become a medical challenge in the present-day aging population. Frequently, those fractures require surgical intervention which ideally relies on autografts or suboptimally on allografts. Therefore, it is pressing and likewise challenging to develop bone substitution materials to heal bone defects. During the differentiation of osteoblasts from their mesenchymal progenitor/stem cells and of osteoclasts from their hemopoietic precursor cells, a lineage-specific release of growth factors and a trans-lineage homeostatic cross-talk via signaling molecules take place. Hence, the major hurdle is to fab…