Amorphous calcium phosphate nanoparticles allow fingerprint detection via self-activated luminescence

Tailoring the structure and self-activated photoluminescence of carbonated amorphous calcium phosphate nanoparticles for bioimaging applications

“…49 In this case, the broadening of ν 3 PO 4 and ν 4 PO 4 bands can be used to monitor changes in SRO, which can be represented by the variations in the FWHM values of these bands. 22,57 No clear trends in the calculated FWHM values within the 128–140 cm −1 ( ν 3 PO 4 ) and 77–83 cm −1 ( ν 4 PO 4 ) ranges (Fig. S5, ESI†) were observed among the as-synthesized samples.…”

“…The highest FWHM values were observed in ACP2-HT (180 and 87 cm −1 for ν 3 and ν 4 ) and ACP3-HT (175 and 88 cm −1 for ν 3 and ν 4 ), indicating that these samples exhibited the highest degree of disorder at short-range, characterized by increased absorption of various frequencies resulting from fluctuations in P–O bond lengths and in the O–P–O bond angles within distorted PO 4 tetrahedra. 22…”

“…This enabled the determination of the full width at half maximum (FWHM) parameter for these bands, providing insight into the degree of SRO in the ACP structure. 22 The second derivative analysis was conducted using Origin 2022b software, following the procedure outlined by Uskoković. 47…”

“…21 Furthermore, our preliminary study demonstrated that the lattice disorder and defects in chemically-precipitated ACP NPs heat-treated at 400 °C gives rise to intense self-activated broadband PL emission in the visible region. 22…”

“…However, it should be noted that ACP NPs are metastable in solution and tend to convert into calcium deficient carbonated HA over a short period of time. 16,22 To overcome this issue, we employed a functionalization strategy using citrate ions. These biocompatible species, constituting approximately 5.5 wt% of the total organic components in bones, exhibit a strong affinity for both synthetic and biogenic HA NP surfaces, influencing their crystallization pathways from ACP precursors and assembly mechanisms.…”