Phosphate-Based Glasses for Biomedical Applications

Phosphate-based glasses (PBGs) are fully degradable inorganic materials composed primarily of phosphorus pentoxide networks modified by metal oxides such as calcium, sodium and magnesium. Their inherent solubility and easily tunable degradation rates distinguish them from silicate and borate counterparts, enabling controlled release of therapeutic ions and minimising long-term foreign-body presence. PBGs can be produced via melt-quenching or sol–gel routes and shaped into bulk monoliths, fibres, microspheres or scaffolds to address diverse clinical needs in bone repair, soft-tissue regeneration and drug delivery. The degree of network connectivity—reflecting the balance of bridging and non-bridging oxygens—governs both dissolution kinetics and mechanical performance. Incorporation of dopants such as silver, zinc, strontium or titanium imparts antimicrobial, osteoinductive or stability-enhancing properties. In vitro studies in simulated body fluid demonstrate rapid formation of apatite-like layers, while in vivo evaluations reveal biocompatibility, osteoconductivity and effective tissue infiltration. Current research priorities include optimisation of glass composition, fibre architectures for composite reinforcement and mesoporous designs for dual structural support and controlled release, emphasising the global potential of PBGs in orthopaedics, wound management and regenerative medicine.

Research from Nature Portfolio

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Research from all publishers

Recent studies have demonstrated that electrospun phosphate glass fibres doped with silver, zinc or iron accelerate wound healing by releasing therapeutic ions. In ex vivo human skin models, glass fibres with ≥4 mol % silver achieved up to 84 % wound closure in 48 hours and exhibited broad-spectrum antibacterial activity, illustrating a promising platform for chronic wound interventions.

Novel phosphate bioactive glasses and glass-ceramics produced by melt-quenching with calcium hydroxide, potassium fluoride and additives such as titanium or zinc have been shown to develop an apatite-like surface layer in simulated body fluid. Structural characterization links the presence of β-pyrophosphate phases to enhanced in vitro bioactivity, guiding future bone regeneration material design.

In an ovine bone defect model, implantation of porous phosphate-glass microspheres revealed that variation in degradation rate markedly influenced tissue architecture and matrix mineralisation over 13 weeks. Faster-degrading formulations promoted mineral deposition, while slower-degrading compositions fostered denser interconnected tissue, underlining the importance of dissolution kinetics in orthobiologic strategies.

Phosphate-Based Glasses for Biomedical Applications publication trend

The graph below shows the total number of articles in phosphate-based glasses for biomedical applications across all publications each year (not limited to Nature Index journals).

Technical terms

Network connectivity: A measure of glass structure quantifying bridging versus non-bridging oxygens, controlling dissolution rate and mechanical behaviour.

Melt-quenching: A fabrication technique involving rapid cooling of molten glass to produce an amorphous material with specified composition.

Sol–gel method: A low-temperature chemical synthesis route that forms glasses through hydrolysis and condensation, allowing mesoporous and nano-scale architectures.

Simulated Body Fluid (SBF): An aqueous solution mirroring human plasma ion concentrations, used to assess glass bioactivity via apatite layer formation.

Therapeutic ion release: Controlled delivery of biologically active ions (e.g., Ag⁺, Zn²⁺, Sr²⁺) from degrading glasses to elicit antimicrobial, osteogenic or anti-inflammatory responses.

References

1. Wound Healing Promotion via Release of Therapeutic Metallic Ions from Phosphate Glass Fibers: An In Vitro and Ex Vivo Study. ACS Applied Materials & Interfaces (2024).
2. Novel phosphate bioglasses and bioglass-ceramics for bone regeneration. Ceramics International (2024).
3. Porous Phosphate-Based Glass Microspheres Show Biocompatibility, Tissue Infiltration, and Osteogenic Onset in an Ovine Bone Defect Model. ACS Applied Materials & Interfaces (2019).