³¹P and ¹³C solid‐state NMR spectroscopy to study collagen synthesis and biomineralization in polymer‐based bone implants

Abstract

A combination of solid-state NMR spectroscopy and MRI was used to evaluate the formation of extracellular matrix in poly(D,L-lactide-co-glycolide) (PLGA) bone implants. Porous PLGA scaffolds were implanted into rat tibiae and analysed after 2, 4 or 8 weeks. MRI clearly delineated the implants within the cancellous bone. Differences in the trabecular structure of the implanted material and native bone were demonstrated. In addition, implants were analyzed by solid-state NMR spectroscopy under magic angle spinning. (13)C NMR spectra showed the unambiguous signature of collagen formed in the scaffolds, but also the characteristic signals of the PLGA matrix, indicating that resorption was not complete after 8 weeks. Furthermore, (31)P NMR spectroscopy detected the inorganic component of the matrix, which is composed of bioapatite. (31)P NMR spectra were quantified and this analysis revealed that the amount of inorganic extracellular matrix formed de novo was significantly lower than in native bone. This demonstrates that solid-state NMR spectroscopy, in particular in combination with MRI, can provide useful information on the composition and structure of the extracellular matrix, and serve as a tool to evaluate the quality of tissue engineering strategies.

NMR Techniques in Metabolomic Studies: A Quick Overview on Examples of Utilization

“…It is necessary to use high spinning rates because they have to be higher than or similar to the interaction strength: and especially the dipolar couplings between two hydrogen atoms are quite strong. When lower spinning rates are used, a series of narrow peaks is obtained, separated by equal intervals (equal to multiples of the applied frequency of rotations) [33].

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“…HRMAS techniques allow to achieve better resolution; however, the factors influencing line broadening are highly dependent on the material structure and enable, for example, investigation of bone mineralization [33]. This is why there are few methods that make it possible to conduct recoupling of the anisotropic Hamiltonians and to separate the anisotropic and isotropic interactions, thanks to which more comprehensive data can be obtained that inform us about the material structure [33].…”

“…This is why there are few methods that make it possible to conduct recoupling of the anisotropic Hamiltonians and to separate the anisotropic and isotropic interactions, thanks to which more comprehensive data can be obtained that inform us about the material structure [33]. …”

“…This is why in such experiments signal intensity must be compared over a variety of contact times, and not only for its fixed value. Such investigations were carried out considering the phosphorus components and their structure in bone (the graph of intensity vs. contact time is strongly dependent on the material structure) [36–39] and bone implants [33] (Fig. 9).…”

Ultra fast magic angle spinning solid – state NMR spectroscopy of intact bone

“…[14,15] Hitherto, ssNMR has become a robust and imminent tool to study biomaterials such as bone. [16][17][18][19][20][21][22][23][24] ssNMR can be exclusively implemented to study all the three major components of bone, organic part, [25][26][27] inorganic part [28][29][30][31] and water. [32][33][34] ssNMR has been employed to observe different types of water molecules and their pivotal role in determining the mechanical properties of bone.…”