Characterization of organic matrix extracted from fresh water pearls

Utilizing X-ray diffraction in conjunction with competitive adaptive reweighted sampling (CARS) and principal component analysis for the discrimination of medicinal pearl powder and nacre powder

Nacre powder, often utilized to counterfeit medicinal pearl powder due to their similar chemical composition and appearance, poses a challenge in product authentication. This study introduces a rapid and efficient method for distinguishing between medicinal pearl powder and nacre powder using X-ray diffraction in conjunction with principal component analysis (PCA). The X-ray diffraction pattern underwent preprocessing techniques including smoothing denoising (Savitzky-Golay filter, 5-point) and second-order derivative analysis. Subsequently, PCA was employed for dimensionality reduction modeling. The CARS method was applied to select optimal variables for model refinement, determining the data preprocessing approach and key modeling variables. This method demonstrates the capability to accurately differentiate between pearl powder, nacre powder, and even counterfeit samples containing up to 90% pearl powder. With a high accuracy rate, swift operational speed, and potential for automation, this approach shows promise for practical implementation in the realm of pearl powder quality control.

The Application of Pearls in Traditional Medicine of China and Their Chemical Constituents, Pharmacology, Toxicology, and Clinical Research

Although pearls are well known by most people, their medicinal value has not been popularized. This article collates the medicinal history of pearls over 2,000 years in China, including the application of pearls in the traditional medicine of China and their various preparations, as well as the progress of their chemical constituents, pharmacology, toxicology, and clinical research. Pearls from three different sources are used as medical materiel by 9 nationalities and 251 prescription preparations in China. In addition, pearls contain various inorganic constituents, such as calcium carbonate, trace elements, and water, and organic constituents, such as amino acids. In terms of pharmacology, pearls have many effects such as calming, improving cognitive ability, being anti-epileptic, promoting bone growth and regeneration, promoting the proliferation and migration of human microvascular endothelial cells, protecting the heart, anti-hemolysis, and anti-oxidation. In terms of toxicology, pearls are safe to take for a long time without exerting obvious adverse reactions. In terms of clinical application, pearls have been used to treat many diseases and conditions, such as convulsions, epilepsy, palpitations, eye diseases, ulcer diseases, skin diseases, or skin lesions. This article provides a reference for the application and research of pearls in the future.

The proteomics of the freshwater pearl powder: Insights from biomineralization to biomedical application

The freshwater pearl is one kind of valuable organic jewelry and traditional Chinese medicine (TCM). However, the molecular basis of matrix protein in pearl biomineralization and biomedical applications are largely unknown to date. In this study, the matrix proteins of water-soluble matrix, acid-soluble matrix and acid-insoluble matrix from the freshwater seedless pearl powder were detected using liquid chromatography-tandem mass spectrometry (LC-MS/MS) respectively, and identified against the transcriptomic database of the pearl sac. The results showed that a total of 190 proteins were identified in pearl proteomics, which was divided into eight categories by their potential biomineralization functions. The composition of pearl matrix proteins and the high frequency conserved domains like carbonic anhydrase, von Willebrand factor type A, tyrosinase and chitin binding 2 in protein sequences, implying that the "chitin-silk fibroin gel proteins-acidic macromolecules" model was suitable for description the pearl biomineralization process. Meanwhile, ninety-one of pearl matrix proteins could be classified into seven categories by their potential medical functions including wound healing, osteogenic property, antioxidant activity, neuro-regulation effects, skin lightening effect, anti-inflammatory and anti-apoptotic effects and other immunomodulatory property. In general, these results provided valuable new insights into not only the diversity of pearl matrix protein for mollusc biomineralization, but the molecular basis of pearl matrix proteins responsible for their diverse biological properties in TCM application. SIGNIFICANCE: The significance of this study included the following points.

3D printed hydroxyapatite-nacre-starch based bone grafts: Evaluation of biological and mechanical properties

The possibilities of utilizing nacre as a reinforcing material to manufacture 3D printed bone grafts are yet to be explored. This work reports the feasibility of fabricating 3D printed nacre-hydroxyapatitestarch composite bone graft substitutes, emphasizing the effects of nacre addition on biological and mechanical properties. Pressure-less extrusion-based 3D printing of ceramic-polymer viscous slurry is challenging due to the composition and process-parameter variations. To overcome these challenges, a dual extrusion solid freeform fabricator (SFF) has been designed. An increase in nacre loading improves the compressive strength from 9.5 ± 0.1 MPa to 11.7 ± 0.2 MPa, without any post-processing or sintering. Nacre's in vitro osteogenic properties lead to a slight increase in hFOB cellular attachment on the graft surface by day 11. The fabricated structures show good mechanical integrity during the dissolution study in simulated body fluid (SBF). These bone graft substitutes may be utilized to repair low load bearing skeletal defects.

Green efficient ultrasonic-assisted extraction of abalone nacre water-soluble organic matrix for bioinspired enamel remineralization

Reconstructing enamel-like hydroxyapatite structures on damaged teeth remains a great challenge in the materials science and dentistry due to its highly ordered hierarchical microstructure. Inspired by the mineralization of mollusk nacre in nature, abalone nacre water-soluble organic matrix (WSM) was isolated successfully though an ultrasonic-assisted water extraction (UWE) strategy with nondestructive activity and high-quality extraction for simulating the process of tooth hard tissue mineralization. Results showed that the UWE strategy significantly increased the protein yield from 7.60% to 9.60% and improved the polysaccharide yield from 2.59% to 3.34%, respectively, indicating its excellent extraction efficiency of WSM. Noteworthily, the smallest averaged particle size (~155 nm) of WSM were obtained at an ultrasound time of 6 h, whereas the highest absolute values (~ -32 mV) of zeta potential was produced. Moreover, it was proved that WSM could induce the growth of enamel-like hydroxyapatite crystals to further facilitate biomimetic remineralization of the demineralized enamel and restore its continuous and smooth surface structure in vitro. Besides, the hardness (4.37 ± 0.07 GPa) and modulus of elasticity (84.80 ± 1.49 GPa) of the WSM-repaired enamel was similar to that of native enamel, indicating superior mechanical properties after repair. Herein, it provides a promising green, efficient strategy for the remineralization of damaged enamel and high value utilization of waste abalone shells.

Efficacy of Water-Soluble Pearl Powder Components Extracted by a CO2 Supercritical Extraction System in Promoting Wound Healing

Pearl powder is a biologically active substance that is widely used in traditional medicine, skin repair and maintenance. The traditional industrial extraction processes of pearl powder are mainly based on water, acid or enzyme extraction methods, all of which have their own drawbacks. In this study, we propose a new extraction process for these active ingredients, specifically, water-soluble components of pearl powder extracted by a CO2 supercritical extraction system (SFE), followed by the extraction efficiency evaluation. A wound-healing activity was evaluated in vitro and in vivo. This demonstrated that the supercritical extraction technique showed high efficiency as measured by the total protein percentage. The extracts exhibited cell proliferation and migration-promoting activity, in addition to improving collagen formation and healing efficiency in vivo. In brief, this study proposes a novel extraction process for pearl powder, and the extracts were also explored for wound-healing bioactivity, demonstrating the potential in wound healing.

Pearl Powder-An Emerging Material for Biomedical Applications: A Review

Pearl powder is a well-known traditional Chinese medicine for a variety of indications from beauty care to healthcare. While used for over a thousand years, there has yet to be an in-depth understanding and review in this area. The use of pearl powder is particularly growing in the biomedical area with various benefits reported due to the active ingredients within the pearl matrix itself. In this review, we focus on the emerging biomedical applications of pearl powder, touching on applications of pearl powder in wound healing, bone repairing, treatment of skin conditions, and other health indications.

Extraction, Purification, Bioactivities and Application of Matrix Proteins From Pearl Powder and Nacre Powder: A Review

Natural pearls are formed when sand or parasites (irritants) accidentally enter into the oyster body and form pearls under the cover of the nacre layer. Pearl powder is a powdery substance by grinding pearls into small grains, however, the nacre powder is the inner layer of outer corner layer and middle prism layer. Pearl medicine in China has a history of more than 2,000 years, pearl has the effects of calming the mind, clearing the eyes, detoxifying the muscle and so on. In this paper, the researches on the extraction of pearl powder and nacre powder, the isolation and purification of matrix protein and the various biological activities (osteogenic activity, antioxidant, anti-inflammatory, anti-apoptotic, promoting the migration of fibroblasts, and so on) are reviewed in detail. To provide readers with a faster understanding, the method of extraction and purification and the application of nacre powder and pearl powder are clearly presented in the form of figures and tables. In line with the concept of waste or by-product, there are more reports of nacre extract than pearl extract, due to the expensive and limited in origin of pearls. Mainly on the direct use of nacre powder and pearl powder or on the use of extracts (mainly water soluble proteins) through experiments in vivo or in vitro, and shows whether it is effective through the results of various indexes. There is no further study on substances other than extracts, and the structural analysis of extracts needs further exploration.

Preparation, Characterization and In Vitro Biological Evaluation of a Novel Pearl Powder/Poly-Amino Acid Composite as a Potential Substitute for Bone Repair and Reconstruction

Many studies about fabricating organic-inorganic composite materials have been carried out in order to mimic the natural structure of bone. Pearl, which has a special block-and-mortar hierarchical structure, is a superior bone repair material with high osteogenic activity, but it shows few applications in the clinical bone repair and reconstruction because of its brittle and uneasily shaped properties. In this work, pearl powder (P)/poly (amino acid) (PAA) composites were successfully prepared by a method of in situ melting polycondensation to combine the high osteogenic activity of the pearl and the pliability of the PAA. The mechanical properties, in vitro bioactivity and biocompatibility as well as osteogenic activity of the composites were investigated. The results showed that P/PAA composites have both good mechanical properties and bioactivity. The compressive strength, bending strength and tensile strength of the composites reached a maximum of 161 MPa, 50 MPa and 42 MPa, respectively; in addition, apatite particles successfully deposited on the composites surface after immersion in simulated body fluid (SBF) for 7 days indicated that P/PAA composites showed an enhanced mineralization capacity and bioactivity due to incorporation of pearl powder and PAA. The cell culture results revealed that higher cell proliferation and better adhesion morphology of mouse bone marrow mesenchymal stem cells (MSCs) appeared on the composite surface. Moreover, cells growing on the surface of the composites exhibited higher alkaline phosphatase (ALP) activity, more calcium nodule-formation, and higher expression levels of osteogenic differentiation-related genes (COL 1, RunX2, OCN, and OPN) than cells grown on PAA surface. The P/PAA composites exhibited both superior mechanical properties to the pearl powder, higher bioactivity and osteogenic capability compared with those of PAA.

Rapid identification of pearl powder from Hyriopsis cumingii by Tri-step infrared spectroscopy combined with computer vision technology

Pearl powder, an important raw material in cosmetics and Chinese patent medicines, is commonly uneven in quality and frequently adulterated with low-cost shell powder in the market. The aim of this study is to establish an adequate approach based on Tri-step infrared spectroscopy with enhancing resolution combined with chemometrics for qualitative identification of pearl powder originated from three different quality grades of pearls and quantitative prediction of the proportions of shell powder adulterated in pearl powder. Additionally, computer vision technology (E-eyes) can investigate the color difference among different pearl powders and make it traceable to the pearl quality trait-visual color categories. Though the different grades of pearl powder or adulterated pearl powder have almost identical IR spectra, SD-IR peak intensity at about 861cm^-1 (v₂ band) exhibited regular enhancement with the increasing quality grade of pearls, while the 1082cm^-1 (v₁ band), 712cm^-1 and 699cm^-1 (v₄ band) were just the reverse. Contrastly, only the peak intensity at 862cm^-1 was enhanced regularly with the increasing concentration of shell powder. Thus, the bands in the ranges of (1550-1350cm^-1, 730-680cm^-1) and (830-880cm^-1, 690-725cm^-1) could be exclusive ranges to discriminate three distinct pearl powders and identify adulteration, respectively. For massive sample analysis, a qualitative classification model and a quantitative prediction model based on IR spectra was established successfully by principal component analysis (PCA) and partial least squares (PLS), respectively. The developed method demonstrated great potential for pearl powder quality control and authenticity identification in a direct, holistic manner.

3D printing of pearl/CaSO4 composite scaffolds for bone regeneration

The development of biomaterials with high osteogenic ability for fast osteointegration with a host bone is of great interest. In this study, pearl/CaSO₄ composite scaffolds were fabricated using three-dimensional (3D) printing, followed by a hydration process. The pearl/CaSO₄ scaffolds showed uniform interconnected macropores (∼400 μm), high porosity (∼60%), and enhanced compressive strength. With CaSO₄ scaffolds as a control, the biological properties of the pearl/CaSO₄ scaffolds were evaluated in vitro and in vivo. The results showed that the pearl/CaSO₄ scaffolds possessed a good apatite-forming ability and stimulated the proliferation and differentiation of rat bone mesenchymal stem cells (rBMSCs), as well as giving a better expression of related osteogenic genes. Importantly, micro-computed tomography and histology of the critical-sized rabbit femoral condyle defects implanted with the scaffolds illustrated the osteogenic capacity of the pearl/CaSO₄ scaffolds. New bone was observed within 8 weeks. The bone-implant contact index was significantly higher for the pearl/CaSO₄ scaffolds implant than for the CaSO₄ scaffolds implant, indicating that the pearl/CaSO₄ scaffolds would be promising implants for bone regeneration.

Hyriopsis cumingii Hic52-A novel nacreous layer matrix protein with a collagen-like structure

Nacre is a product of a precisely regulated biomineralization process and a major contributor to the luster of pearls. Nacre is composed of calcium carbonate and an organic matrix of proteins that is secreted from mollusc mantle tissue and is exclusively associated with shell formation. In this study, hic52, a novel matrix protein gene from mantle of Hyriopsis cumingii, was cloned and functionally analyzed. The full-length cDNA of hic52 encoded 542 amino acids and contained a signal peptide of 18 amino acids. Excluding the signal peptide, the theoretical molecular mass of the polypeptide was 52.2kDa. The predicted isoelectric point was 10.37, indicating a basic shell protein. The amino acid sequence of hic52 featured high proportion of Gly (28.8%) and Gln (12.4%) residues. The predicted tertiary structure was characterized as having similarities to collagen I, alpha 1 and alpha 2 in the structure. The polypeptide sequence shared no homology with collagen. The hic52 expression pattern by quantitative real-time PCR and in situ hybridization exhibits at the dorsal epithelial cells of the mantle. Expression increased during the stages of pearl sac development. The data showed that hic52 is probably a framework shell protein that mediates and controls the nacreous biomineralization process.

A Novel Matrix Protein Hic31 from the Prismatic Layer of Hyriopsis Cumingii Displays a Collagen-Like Structure

In this study, we clone and characterize a novel matrix protein, hic31, from the mantle of Hyriopsis cumingii. The amino acid composition of hic31 consists of a high proportion of Glycine residues (26.67%). Tissue expression detection by RT-PCR indicates that hic31 is expressed specifically at the mantle edge. In situ hybridization results reveals strong signals from the dorsal epithelial cells of the outer fold at the mantle edge, and weak signals from inner epithelial cells of the same fold, indicating that hic31 is a prismatic-layer matrix protein. Although BLASTP results identify no shared homology with other shell-matrix proteins or any other known proteins, the hic31 tertiary structure is similar to that of collagen I, alpha 1 and alpha 2. It has been well proved that collagen forms the basic organic frameworks in way of collagen fibrils and minerals present within or outside of these fibrils. Therefore, hic31 might be a framework-matrix protein involved in the prismatic-layer biomineralization. Besides, the gene expression of hic31 increase in the early stages of pearl sac development, indicating that hic31 may play important roles in biomineralization of the pearl prismatic layer.

A crucial process: organic matrix and magnesium ion control of amorphous calcium carbonate crystallization on β-chitin film

ACC transformation processes occurring on chitin film mediated by a water soluble matrix or magnesium ions in aqueous solution were investigated.

STRUCTURAL FEATURES AND MECHANICAL PROPERTIES OF PLLA/PEARL POWDER SCAFFOLDS

In order to improve the mechanical properties of scaffolds for bone tissue engineering, the present study aims to bring calcium carbonate (CaCO3) with signaling molecules, namely pearl powder, into poly(L-lactic acid) (PLLA). PLLA/aragonite and PLLA/vaterite scaffolds were successfully fabricated by the freeze-drying method. Both composite scaffolds had a similar porous structure but a different saturated content of pearl powders. For both scaffolds, the porosity decreases and yield strength increases as pearl powder content increases. Introducing pearl powders into PLLA can improve the mechanical properties of the scaffolds. The porous structure plays a crucial role in the yield strength of pure PLLA scaffolds, whereas the yield strength of PLLA/pearl powder scaffolds mostly relies on pearl powder content.

What is the difference in organic matrix of aragonite vs. vaterite polymorph in natural shell and pearl? Study of the pearl-forming freshwater bivalve mollusc Hyriopsis cumingii

Aragonite pearl, vaterite pearl and shell nacre of the freshwater mollusc Hyriopsis cumingii (Zhejiang province, China) were chosen to analyze microstructure and organic composition in the different habits of calcium carbonate. SEM and TEM were used to reveal the microstructure and mineralogical phase. We found that tablets in vaterite exhibited more irregular texture and were packaged with more organic matrices than in aragonite forms. Then a peculiar method was introduced to extract water soluble matrix (WSM), acid soluble matrix (ASM) and acid insoluble matrix (AIM) from the three samples, and biochemical analysis of these organic matrixes involved in crystal formation and polymorph selection was carried out. High performance liquid chromatography (HPLC) confirms the hydrophobic pattern of the organic matrix intermingled with mineral, the opposite of the early mobilizable water soluble fraction. Amino acid composition confirms hydrophobic residues as major components of all the extracts, but it reveals an imbalance in acidic residues rates in WSM vs. ASM and in aragonite vs. vaterite. Electrophoresis gives evidence for signatures in proteins with a 140 kDa material specific for aragonite in WSM. Conversely all ASM extracts reveal the presence of about 55 kDa components, including a discrete band in vaterite extract.