Correction: Yu et al. Rare-Earth-Metal (Nd3+, Ce3+ and Gd3+)-Doped CaF2: Nanoparticles for Multimodal Imaging in Biomedical Applications. Pharmaceutics 2022, 14, 2796

In the original publication [...].


Figure Legend
In the original publication [1], there was a mistake in the legend for Figure 8.The legends of Figure 8b-d are inaccurate and need to be corrected.The correct legend appears below.The authors state that the scientific conclusions are unaffected.This correction was approved by the Academic Editor.The original publication has also been updated.

Error in Figure
In the original publication, there was a mistake in Figure 8, as published.The original MRI data of Figure 8b-d were incomplete and not analyzed correctly.The corrected Figure 8 appears below.The authors state that the scientific conclusions are unaffected.This correction was approved by the Academic Editor.The original publication has also been updated.

Text Correction
There was an error in the original publication.In the introduction, one word is missing in the full name of SPECT.
A correction has been made to 1. Introduction, Paragraph 1: Imaging holds a crucial role in the diagnosis of a variety of diseases, such as cancer.Early-stage disease diagnosis is important to maximize treatment effects and to personalize treatments based on the patient's individual variability and medical profile.Molecular imaging techniques provide comprehensive anatomical, physiological, and functional information on disease detection and the monitoring of treatment responses.The most commonly used diagnostic imaging methods during the past few decades in the medical field include MRI, X-ray computed tomography (CT) [1], positron emission tomography (PET) [2,3], single-photon emission computed tomography (SPECT) [4], optical fluorescent light imaging (FLI) and photoacoustic imaging (PAI) [5].Due to differences in their detection methods, spatiotemporal resolution, sensitivity and probe types, the diagnostic information obtained is divergent.Both PET and SPECT use γ rays to detect the in vivo distribution of radioactive tracers to obtain information on biological functions.They have the disadvantages of low spatial resolution, radiation risks and high costs [6][7][8][9][10].Optical imaging uses visible light and near-infrared probes with different spectral characteristics for molecular and cellular detection but faces several limitations, such as photobleaching, low tissue penetration power, low spatial resolution and autofluorescence [11][12][13][14][15].While CT, MRI and PAI can provide structural information, CT detection relies on contrast agents (such as iodine or barium) to obtain images via the different absorption of X-rays by bio-

Text Correction
There was an error in the original publication.In the introduction, one word is missing in the full name of SPECT.[16,17].MRI, a non-invasive imaging technology uses radio waves (magnetic field), but it has low sensitivity, high cost and scanning and image processing are timeconsuming [18][19][20].PAI uses high-frequency sound waves (>20 kHz) to generate acoustic energy to detect the difference in echo between chromophores or microbubbles and surrounding tissues in real time.However, due to the limited resolution and sensitivity, the data reproducibility is low, and it cannot provide accurate results [8,[21][22][23].In summary, to predict and treat diseases more comprehensively and accurately, it is imperative to develop a simple and efficient multifunctional nanomaterial that can integrate multiple imaging modes for detection.
There was an error in the original publication.There is a mistake in the description.
A correction has been made to 1. Introduction, Paragraph 4: Since the radius of Nd 3+ is not much different from that of Ca 2+ , trivalent Nd ions replace the crystal sites of divalent Ca ions when they are doped into the CaF 2 lattice, requiring more F − for charge compensation, but they do not cause obvious crystal changes.However, when the Nd 3+ doping concentration reaches a certain limit, Nd 3+ aggregates and some energy cross-relaxation occurs, which triggers the cluster effect and reduces the luminous efficiency of the nanomaterials [40,41].In order to overcome this phenomenon, the introduction of optically inactive ions (such as Lu 3+ , Gd 3+ , Y 3+ , Yb 3+ ) can effectively destroy the formation of Nd-Nd clusters, thereby improving the quantum efficiency of the material [42][43][44][45].Notably, the special properties of certain optically inactive ions also offer the possibility of constructing multimodal probes; however, most current multimodal imaging probes are dual-mode probes, and NIR-II-based imaging systems combining more than two modes are still rarely reported, but our previous study demonstrates that triple-mode imaging probes hold great promise for obtaining complementary information.Therefore, we focus on the field of rare-earth triple-mode imaging probes for more exploration [46].Wang et al. showed that the luminous efficiency of CaF 2 : Nd co-doped Ce 3+ was 10.4 times higher than that of CaF 2 : Nd [47].On the other hand, the seven unpaired electrons of Gd(III) can increase the proton relaxation rate, making Gd 3+ a common contrast agent in MR bioimaging [48,49].Therefore, we choose Ce 3+ , Gd 3+ and Nd 3+ co-doping CaF 2 as the material in our strategy to construct an imaging mode combining NIR-II imaging with complementary MRI and PAI.
There was an error in the original publication.There is a need to correct some details.
There was an error in the original publication.We discovered errors in the reporting and interpretation of the MRI properties of the nanoparticles.
A correction has been made to 3. Results and Discussion, Paragraph 10:

Figure 8 .
In vitro MRI performance of CaF 2 : Ce, Gd, Nd NPs.(a) Magnetic properties of CaF 2 : Ce, Gd, Nd NPs; (b) in vitro T 1 -weighted and T 2 -weighted MR images of CaF 2 : Ce, Gd, Nd NPs at different concentrations in water containing 1% agarose gel; (c) MRI signal intensity of CaF 2 : Ce, Gd, Nd NPs with increasing repetition time and echo time at different concentrations; (d) in vitro T 1 relaxation rates and T 2 relaxation rates of various Gd concentrations for CaF 2 : Ce, Gd, Nd NPs; (e) ex vivo MRI images of a mouse cadaver before and after subcutaneous injection of CaF 2 : Ce, Gd, Nd NPs (10 mg/mL).
A correction has been made to 1. Introduction, Paragraph 1: Imaging holds a crucial role in the diagnosis of a variety of diseases such as cancer.Early-stage disease diagnosis is important to maximize treatment effects, and to personalize treatments based on the patient's individual variability and medical profile.Molecular imaging techniques provide comprehensive anatomical, physiological and functional information on disease detection and the monitoring of treatment responses.The most commonly used diagnostic imaging methods during the past few decades in the medical field include MRI, X-ray computed tomography (CT) [1], positron emission tomography (PET) [2,3], single-photon emission computed tomography (SPECT) [4], optical fluorescent light imaging (FLI) and photoacoustic imaging (PAI) [5].Due to differences in their detection methods, spatiotemporal resolution, sensitivity and probe types, the diagnostic information obtained is divergent.Both PET and SPECT use γ rays to detect the in vivo distribution of radioactive tracers to obtain information on biological functions.They have the disadvantages of low spatial resolution, radiation risks and high costs [6-10].Optical imaging uses visible light and near-infrared probes with different spectral characteristics for molecular and cellular detection but faces several limitations, such as photobleaching, low tissue penetration power, low spatial resolution and autofluorescence [11-15].While CT, MRI and PAI can provide structural information, CT detection relies on contrast agents (such as iodine or barium) to obtain images through the different absorption of X-rays by biological tissues, which has the disadvantage of radiation risk and limited soft-tissue resolution