Fast Setting Calcium Phosphate Cement-Chitosan Composite: Mechanical Properties and Dissolution Rates

Abstract

Calcium phosphate cement (CPC) can self-harden in vivo to form hydroxyapatite (HA) with excellent osteoconductivity. In recent studies, CPCchitosan composites are developed with high mechanical strength and washout resistance. The objectives of the present study are to optimize the setting time and mechanical properties of a CPC-chitosan composite by tailoring the chitosan content, and to evaluate the bioresorbability by using an in vitro dissolution model. Six chitosan mass fractions are tested: 0, 10, 15, 20, 25, and 30%. Specimens are immersed in solutions with pH ranging from 3.5 to 5 to simulate the acidic environments produced by osteoclasts in vivo. Dissolution is measured as the fraction of mass loss versus immersion time from 7 d to 28 d. The CPC-chitosan composite with 20% by mass chitosan has a setting time (mean AE SD; n ¼ 4) of 13 AE 1 min, significantly less than 87 AE 7 min for CPC control without chitosan ( p<0.05). The composite flexural strength (mean AE SD; n ¼ 6) was 14 AE 2 MPa, significantly higher than 4 AE 1 MPa of CPC control ( p<0.05). At an intermediate pH of 4.5, the fraction of mass loss for CPC with 20% chitosan and CPC control without chitosan are not significantly different ( p > 0.1). The dissolution rates (fraction of mass loss per day, %/d) were 1.05 for CPC control and 1.08 for CPC-chitosan. In summary, a CPC-chitosan composite is developed with fast-setting and a flexural strength three-fold of that of CPC *Author to whom correspondence should be addressed. E-mail: limin.sun@nist. The strong and resorbable CPC-chitosan composite may be useful in moderate stress-bearing craniofacial and orthopedic repairs.

Self-Setting Calcium Orthophosphate Formulations: Cements, Concretes, Pastes and Putties

“…A knitted two-dimensionally oriented polyglactin fiber-mesh was found to be effective in improving load-bearing behavior of a calcium orthophosphate cement for potential structural repair of bone defects [199]. To make the material stronger, fast setting and anti-washout, chitosan might be added [178,344,403,[424][425][426][427][428][429][430][431][432][433][434]. Furthermore, anti-washout properties might appear by adding sodium alginate [435].…”

Effects of adding resorbable chitosan microspheres to calcium phosphate cements for bone regeneration

“…Because of these properties chitosan has been recently used to improve currently used CPCs [17][18][19]. However, previous studies have mainly focused on adding chitosan to liquid components of CPCs or preparing chitosan fibers for CPC scaffolds [20,21]. A role for chitosan in improving the osteoconductive and degradable properties and pore size distribution of bone cement was not desired.…”

Development and characterization of fast-hardening composite cements composed of natural ceramics originated from horse bones and chitosan solution

“…19 When CPC were mixed with an acidic CS, an increase in the pH resulting from the hardening reaction of CPC causes the soft CPC and CS paste to transform to a hard mass. 20,21 A composite cement consisting of natural ceramics and chitosan therefore is expected to be a good biomaterial for bone tissue engineering. In addition, bioceramics fabricated from natural bones in our study have a nano-size of the inorganic component, and are considered to be important for the mechanical properties and self hardening time.…”