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Materiais bioativos

1969
  • Larry L. Hench
Amostras de bioglass em um laboratório de pesquisa em biomateriais.

(Imagem gerada apenas para fins ilustrativos)

Bioactive materials are a class of biomaterials designed to elicit a specific, positive biological response at the material-tissue interface, resulting in the formation of a bond between them. Unlike bioinert materials that aim for minimal interaction, bioactive materials actively participate in healing processes. A classic example is Bioglass, which forms a hydroxyapatite layer on its surface, bonding directly to bone.

The concept of bioactivity was pioneered by Larry Hench with his 1969 invention of Bioglass® 45S5, a specific composition of 45 wt% SiO2, 24.5% CaO, 24.5% Na2O, and 6% P2O5. The mechanism of bone bonding involves a sequence of five surface chemical reactions. When exposed to bodily fluids, (1) rapid ion exchange of Na+ from the glass with H+ from solution occurs, creating a silica-rich layer. (2) This increases local pH, which causes (3) the glass network to break down, releasing silicic acid (Si(OH)4) and forming silanols (Si-OH) at the surface. (4) A high local concentration of calcium and phosphate ions, both from the glass and surrounding fluid, leads to the formation of an amorphous calcium-phosphate layer. (5) This layer crystallizes into hydroxycarbonate apatite (HCA), which is chemically and structurally similar to the mineral phase of bone. This HCA layer provides a bioactive scaffold for osteoblasts to colonize, differentiate, and deposit new bone matrix, creating a strong, direct, and seamless bond with the host bone. This process, known as osteointegração, is crucial for the long-term stability of implants. Furthermore, the dissolution products, particularly silicic acid, have been shown to stimulate genes within osteoprogenitor cells, upregulating the production of growth factors. This makes the material not only osteoconductive (a scaffold for bone growth) but also osteoinductive (actively stimulating new bone formation).

UNESCO Nomenclature: 3201
Ciências médicas

Tipo

Processo Químico

Interrupção

Revolucionário

Uso

Uso generalizado

Precursores

  • desenvolvimento da ciência e fabricação do vidro
  • understanding of bone composition and the role of hydroxyapatite
  • Uso inicial de cerâmicas inertes como a alumina em ortopedia
  • Avanços nas técnicas de análise de superfície para estudar a interface material-tecido

Aplicações

  • Enxertos ósseos e preenchimento de cavidades em cirurgia ortopédica e odontológica
  • Revestimentos em implantes metálicos (ex.: hastes de quadril) para promover a osseointegração.
  • scaffolds for bone tissue engineering
  • componentes em pastas de dente bioativas para remineralizar o esmalte
  • Curativos cicatrizantes que estimulam a reparação tecidual

Patentes:

  • US3929971A

Ideias de Inovação Potencial

  • bioactive inks for 3d printing patient-specific bone scaffolds
  • ion-releasing dental fillings that inhibit secondary caries and promote dentin regeneration
  • injectable bioactive glass putties for minimally invasive bone repair
  • bioactive coatings for cardiovascular stents that promote endothelialization and prevent restenosis
  • nerve guidance conduits doped with bioactive ions to enhance nerve regeneration
  • bioactive glass nanoparticles for targeted cancer therapy (hyperthermia)
  • antimicrobial bioactive glasses containing silver or copper ions for wound dressings
  • bioactive cements for vertebroplasty that integrate with spinal bone
  • scaffolds that release different ions at different times to orchestrate complex tissue formation
  • bioactive soft materials (hydrogels) for cartilage and soft tissue regeneration
Relacionado a: bioativo, biovidro, Larry Hench, hidroxiapatita, osseointegração, ligação óssea, troca iônica, osteoindução, osteocondução, biomaterial cerâmico.

Contexto histórico

Materiais bioativos

1960
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1969
1976-05-28
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(Caso a data seja desconhecida ou irrelevante, por exemplo, "mecânica dos fluidos", é fornecida uma estimativa aproximada de seu surgimento notável)

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