Silicate, borosilicate, and borate bioactive glass scaffolds with controllable degradation rate for bone tissue engineering applications. I. Preparation and in vitro degradation

Abstract

Bioactive glass scaffolds with a microstructure similar to that of dry human trabecular bone but with three different compositions were evaluated for potential applications in bone repair. The preparation of the scaffolds and the effect of the glass composition on the degradation and conversion of the scaffolds to a hydroxyapatite (HA)-type material in a simulated body fluid (SBF) are reported here (Part I). The in vitro response of osteogenic cells to the scaffolds and the in vivo evaluation of the scaffolds in a rat subcutaneous implantation model are described in Part II. Scaffolds (porosity = 78-82%; pore size = 100-500 microm) were prepared using a polymer foam replication technique. The glasses consisted of a silicate (13-93) composition, a borosilicate composition (designated 13-93B1), and a borate composition (13-93B3), in which one-third or all of the SiO2 content of 13-93 was replaced by B2O3, respectively. The conversion rate of the scaffolds to HA in the SBF increased markedly with the B2O3 content of the glass. Concurrently, the pH of the SBF also increased with the B2O3 content of the scaffolds. The compressive strengths of the as-prepared scaffolds (5-11 MPa) were in the upper range of values reported for trabecular bone, but they decreased markedly with immersion time in the SBF and with increasing B2O3 content of the glass. The results show that scaffolds with a wide range of bioactivity and degradation rate can be achieved by replacing varying amounts of SiO(2) in silicate bioactive glass with B2O3.

Comparison of Borate Bioactive Glass and Calcium Sulfate as Implants for the Local Delivery of Teicoplanin in the Treatment of Methicillin-Resistant Staphylococcus aureus-Induced Osteomyelitis in a Rabbit Model

“…CaSO 4 is known to be osteoconductive but not osteoinductive, and it supports the direct apposition of bone on its surface by mature osteoblasts (28). Borate bioactive glass has been shown to have a better capacity to stimulate bone regeneration than silicate bioactive glasses and calcium phosphate bioceramics (11)(12)(13)(14)(15)(16). In vivo, bioactive glasses are degraded and converted to a carbonate-substituted HA that can remodel into bone.…”

“…Bioactive glasses are unique in their ability to be converted to HA in vivo, in addition to their proven osteoconductivity and their ability to form a strong bond with bone and soft tissues (12,13). Borate bioactive glasses have been attracting greater interest than the more widely known silicate bioactive glasses, such as 45S5 and S53P4, because of their ability to be converted more rapidly and completely to HA (14,15). However, the potential of borate bioactive glass as an antibiotic carrier in the treatment of bone infection is currently unclear due to limited data.…”

Scaffolds in Regenerative Endodontics: A Review.

“…[77] However, for tissue engineering purposes, new BGs based on borate and borosilicate compositions have been suggested, [78][79] the biocompatibility and controllable degradation rate of these new glass scaffolds have been reported. [80,81] When degrades, BG will be converted into an HA-like substance that is able to bond to soft and hard tissues. The degradation also releases ions that contribute in osteogenesis and angiogenesis.…”

High Borate Networks as a Platform to Modulate Temporal Release of Therapeutic Metal Ions Gallium and Strontium

“…Using 15 mL polypropylene Falcon tubes, 0.1 g of each glass composition (45 -150 µm) (n=3) was suspended in 10 mL of tissue culture water (Sigma-Aldrich, Canada) [40][41][42][43]. This was done for each glass composition at each incubation time point: 24, 72, 168, 336 and 720 hours.…”