Low expression of interleukin-1 receptor antagonist correlates with poor prognosis via promoting proliferation and migration and inhibiting apoptosis in oral squamous cell carcinoma.

BACKGROUND: Biomarkers are biochemical indicators that can identify changes in the structure or function of systems, organs, or cells and can be used to monitor a wide range of biological processes, including cancer. Interleukin-1 receptor antagonist (IL1RA) is an important inflammatory suppressor gene and tumor biomarker. The goal of this study was to investigate the expression of IL1RA, its probable carcinogenic activity, and its diagnostic targets in oral squamous cell carcinoma (OSCC). RESULTS: We discovered that IL1RA was expressed at a low level in OSCC tumor tissues compared to normal epithelial tissues and that the expression declined gradually from epithelial hyperplasia through dysplasia to carcinoma in situ and invasive OSCC. Low IL1RA expression was associated not only with poor survival but also with various clinicopathological markers such as increased infiltration, recurrence, and fatalities. Following cellular phenotyping investigations in OSCC cells overexpressing IL1RA, we discovered that recovering IL1RA expression decreased OSCC cell proliferation, migration, and increased apoptosis. CONCLUSIONS: In summary, our investigation highlighted the possible involvement of low-expression IL1RA in OSCC cells in promoting invasive as well as metastatic and inhibiting apoptosis, as well as the efficacy of IL1RA-focused monitoring in the early detection and treatment of OSCC.

Inhibition mechanism of crude lipopeptide from Bacillus subtilis against Aeromonas veronii growth, biofilm formation, and spoilage of channel catfish flesh.

Aeromonas veronii is associated with food spoilage and some human diseases, such as diarrhea, gastroenteritis, hemorrhagic septicemia or asymptomatic and even death. This research investigated the mechanism of the growth, biofilm formation, virulence, stress resistance, and spoilage potential of Bacillus subtilis lipopeptide against Aeromonas veronii. Lipopeptides suppressed the transmembrane transport of Aeromonas veronii by changing the cell membrane's permeability, the structure of membrane proteins, and Na+/K+-ATPase. Lipopeptide significantly reduced the activities of succinate dehydrogenase (SDH) and malate dehydrogenase (MDH) by 86.03% and 56.12%, respectively, ultimately slowing Aeromonas veronii growth. Lipopeptides also restrained biofilm formation by inhibiting Aeromonas veronii motivation and extracellular polysaccharide secretion. Lipopeptides downregulated gene transcriptional levels related to the virulence and stress tolerance of Aeromonas veronii. Furthermore, lipopeptides treatment resulted in a considerable decrease in the extracellular protease activity of Aeromonas veronii, which restrained the decomposing of channel catfish flesh. This research provides new insights into lipopeptides for controlling Aeromonas veronii and improving food safety.

Effect of Novel Processing Techniques on the Carotenoid Release during the Production of Red Guava Juice.

Red guava, distinguished by its elevated lycopene content, emerges as a promising natural source of carotenoids. This study systematically evaluates the impact of diverse processing techniques on the efficient release of carotenoids. The primary objective is to facilitate the transfer of carotenoids into the juice fraction, yielding carotenoid-enriched juice seamlessly integrable into aqueous-based food matrices. The untreated guava puree exhibited a modest release of carotenoids, with only 66.26% of ß-carotene and 57.08% of lycopene reaching the juice. Contrastly, both high-pressure homogenization (HPH) at 25 MPa and enzyme (EM) treatment significantly enhanced carotenoid release efficiency (p < 0.05), while high hydrostatic pressure (HHP) at 400 MPa and pulsed electric field (PEF) of 4 kV/cm did not (p > 0.05). Notably, HPH demonstrated the most substantial release effect, with ß-carotene and lycopene reaching 90.78% and 73.85%, respectively. However, the stability of EM-treated samples was relatively poor, evident in a zeta-potential value of -6.51 mV observed in the juice. Correlation analysis highlighted the interactions between pectin and carotenoids likely a key factor influencing the stable dissolution or dispersion of carotenoids in the aqueous phase. The findings underscore HPH as a potent tool for obtaining carotenoid-enriched guava juice, positioning it as a desirable ingredient for clean-label foods.

Enhancing activity of food protein-derived peptides: An overview of pretreatment, preparation, and modification methods.

Food protein-derived peptides have garnered considerable attention due to their potential bioactivities and functional properties. However, the limited activity poses a challenge in effective utilization aspects. To overcome this hurdle, various methods have been explored to enhance the activity of these peptides. This comprehensive review offers an extensive overview of pretreatment, preparation methods, and modification strategies employed to augment the activity of food protein-derived peptides. Additionally, it encompasses a discussion on the current status and future prospects of bioactive peptide applications. The review also addresses the standardization of mass production processes and safety considerations for bioactive peptides while examining the future challenges and opportunities associated with these compounds. This comprehensive review serves as a valuable guide for researchers in the food industry, offering insights and recommendations to optimize the production process of bioactive peptides.

Composition, processing, and quality control of whole flaxseed products used to fortify foods.

Whole flaxseed (flour) as a good source of omega-3 fatty acid and phytochemicals with excellent nutritional and functional attributes has been used to enrich foods for health promotion and disease prevention. However, several limitations and contemporary challenges still impact the development of whole flaxseed (flour)-enriched products on the global market, such as naturally occurring antinutritional factors and entrapment of nutrients within food matrix. Whole flaxseed (flour) with different existing forms could variably alter the techno-functional performance of food matrix, and ultimately affect the edible qualities of fortified food products. The potential interaction mechanism between the subject and object components in fortified products has not been elucidated yet. Hence, in this paper, the physical structure and component changes of flaxseed (flour) by pretreatments coupled with their potential influences on the edible qualities of multiple fortified food products were summarized and analyzed. In addition, several typical food products, including baked, noodle, and dairy products were preferentially selected to investigate the potential influencing mechanisms of flaxseed (flour) on different substrate components. In particular, the altered balance between water absorption of flaxseed protein/gum polysaccharides and the interruption of gluten network, lipid lubrication, lipid-amylose complexes, syneresis, and so forth, were thoroughly elucidated. The overall impact of incorporating whole flaxseed (flour) on the quality and nutritional attributes of fortified food products, coupled with the possible solutions against negative influences are aimed. This paper could provide useful information for expanding the application of whole flaxseed (flour) based on the optimal edible and nutritional properties of fortified food products.

Evaluation of intraoral optical scanning accuracy for fine structure reconstruction and occlusal records of inlay/onlay preparations.

AIM: The present study aimed to determine the impact of different degrees of salivary contamination and variations in occlusal force during intraoral scanning of inlay/onlay cavities on the accuracy of fine structure reconstruction and occlusal records. MATERIALS AND METHODS: Digital data of inlay/onlay models, collected using an intraoral scanner, were divided into 40 groups according to the restoration type (onlay or inlay), salivary contamination level (none, completely dry; mild, moist but not visually completely apparent; moderate, half-filled cavity; severe, filled-up cavity), and simulated occlusal force (0, 2, 4, 6 or 8 kg). The acquired 120 datasets were used to measure the average interocclusal space and cavity buccolingual internal angle. RESULTS: Salivary contamination and occlusal force did affect the occlusal contact (P < 0.001), but restoration type did not (P > 0.05). An interaction was found between inlay type and salivary contamination (P < 0.001), but not between occlusal force and salivary contamination (P > 0.05). Salivary contamination also affected the accuracy of fine structure reconstruction (P < 0.001), but restoration type did not (P > 0.05), and no interaction was found between the two factors (P > 0.05). The difference in the measured internal angle increased with the increase in salivary contamination. CONCLUSIONS: Intraoral optical scanning of inlay/onlay preparations was reliable for recording occlusal contact but showed uncertainty in cavity fine structure reconstruction when moderate or severe salivary contamination was present in the cavity. Nevertheless, a moist cavity surface with no visually apparent salivary contamination is acceptable. (Int J Comput Dent 2022;25(3):257-265; doi: 10.3290/j.ijcd.b2599691).

Overexpression of membranal SLC3A2 regulates the proliferation of oral squamous cancer cells and affects the prognosis of oral cancer patients.

OBJECTIVE: Oral squamous cell carcinoma (OSCC) is the most common cancer in oral and maxillofacial tissue. This study aimed to investigate the expression of SLC3A2 in human OSCC tissues and its regulatory roles in OSCC. METHODS: The expression of SLC3A2 in human OSCC tissues was assessed using immunohistochemistry. The proliferation, migration, and invasion of oral squamous cells were evaluated after knockdown of SLC3A2. RESULTS: The expression of SLC3A2 in OSCC was higher than that in normal oral epithelial cells. SLC3A2 had higher expression levels in OSCC tissues than that in adjacent normal tissues. Upregulation of SLC3A2 was associated with advanced stages and poor survival of OSCC patients. In vitro experiments showed that knocking down of SLC3A2 was associated with reduced migration, invasion, and proliferation, but increased apoptosis of OSCC cells. CONCLUSION: SLC3A2 exerted a harmful effect on OSCC patients by increasing migration, invasion and proliferation, and decreasing apoptosis.

Oligomeric Procyanidin Nanoliposomes Prevent Melanogenesis and UV Radiation-Induced Skin Epithelial Cell (HFF-1) Damage.

The potential protective effect of nanoliposomes loaded with lotus seedpod oligomeric procyanidin (LSOPC) against melanogenesis and skin damaging was investigated. Fluorescence spectroscopy showed that, after encapsulation, the LSOPC-nanoliposomes still possessed strong inhibitory effects against melanogenesis, reducing the activity of both monophenolase and diphenolase. Molecular docking indicated that LSOPC could generate intense interactive configuration with tyrosinase through arene-H, arene-arene, and hydrophobic interaction. An ultraviolet radiated cell-culture model (human foreskin fibroblast cell (HFF-1)) was used to determine the protective effects of the LSOPC-nanoliposomes against skin aging and damage. Results showed that LSOPC-nanoliposomes exerted the highest protective effects against both ultraviolet B (UVB) and ultraviolet A (UVA) irradiation groups compared with non-encapsulated LSOPC and a control (vitamin C). Superoxide dismutase (SOD) and malonaldehyde (MDA) assays demonstrated the protection mechanism may be related to the anti-photooxidation activity of the procyanidin. Furthermore, a hydroxyproline assay suggested that the LSOPC-nanoliposomes had a strong protective effect against collagen degradation and/or synthesis after UVA irradiation.

Simulation training for ceramic crown preparation in the dental setting using a virtual educational system.

OBJECTIVES: The aim was to evaluate the effectiveness of a pre-clinical training of ceramic crown preparation using the Virtual Educational System for Dentistry. MATERIAL AND METHODS: Fifty-seven dental students were recruited to prepare a ceramic crown under the guidance of the Real-time Dental Training and Evaluation System (RDTES) in order to collect pre-learning data. They participated in the online virtual learning course independently on the Virtual Learning Network Platform (VLNP). One week later, the students were invited to complete their post-learning crown preparation with the RDTES. A questionnaire survey explored students' perceived benefits or drawbacks of the virtual educational system. Students were allocated into Group A (n = 15), B (n = 24) and C (n = 18) based on their pre-learning performance. Differences of assessment results amongst different groups were evaluated by ANOVA and Kruskal-Wallis tests. The pre- and post-learning assessment results in all groups were compared using paired t tests or Wilcoxon signed rank tests. RESULTS: The error scores for four assessment items (instrument selection, preparation section, preparation reduction, preparation surface and profile) and total score of outcome assessment after the virtual learning were significantly different with those before the virtual learning (P < 0.05). There were significant interactions between time and student group in the mean scores of process and outcome assessments (P < 0.001), except for the assessment item "damage of adjacent teeth." CONCLUSION: The application of a Virtual Educational System for Dentistry with the VLNP and RDTES in pre-clinical operative training helps students improve their clinical skills.

Discovery and preclinical validation of proteomic biomarkers in saliva for early detection of oral squamous cell carcinomas.

OBJECTIVES: Our aim was to identify and prevalidate a set of salivary proteins that can distinguish oral squamous cell carcinomas (OSCC) patients from healthy individuals and patients with oral potentially malignant disorders (OPMD). SUBJECTS AND METHODS: Proteomes of 60 saliva samples from healthy individuals, OPMD patients, and OSCC patients were assayed using the isobaric tags for relative and absolute quantitation (iTRAQ) method. Enzyme-linked immunosorbent assay (ELISA) was used to prevalidate the candidate biomarkers in an independent sample set (n = 90). RESULTS: In total, 246 differentially expressed proteins were identified by comparing each two groups, and 21 proteins were differentially expressed when OSCC was compared with both OPMD and Control. Three proteins, namely, solute carrier family 3 member 2 (SLC3A2), S100 calcium-binding protein A2 (S100A2), and interleukin-1 receptor antagonist protein (IL1RN), were selected as candidate biomarkers. Comparing the OSCC group with the healthy group, the area under curve (AUC) of the three combined biomarkers was 0.89, with a sensitivity of 83.33% and a specificity of 83.33%. Comparing the OSCC group with the OPMD group, the AUC value was 0.87, with a sensitivity of 93.33% and a specificity of 70.00%. CONCLUSION: Our study indicates that salivary proteomics is promising for the discovery of OSCC biomarkers.

Potential TSPO Ligand and Photooxidation Quencher Isorenieratene from Arctic Ocean Rhodococcus sp. B7740.

Due to its special aromatic structure, isorenieratene is thought to be an active natural antioxidant and photo/UV damage inhibitor. In this work, isorenieratene that was extracted from Rhodococcus sp. B7740 isolated from the Arctic Ocean, showed excellent scavenging ability of both singlet oxygen and hydroxyl radical in the UVB-induced auto-oxidation process using the EPR method. Within an ARPE-19 cell model damaged by UVB radiation, isorenieratene showed fine protective effects (1.13 ± 0.03 fold) compared with macular xanthophylls (MXs) through upregulating of tspo. The molecular docking was firstly performed to investigate the interaction of isorenieratene with TSPO as a special ligand. Results showed isorenieratene might form a better binding conformation (S-score -8.5438) than MXs and indicate that isorenieratene not only can function as a direct antioxidant but also activate tspo in ARPE-19 cells. Thus, isorenieratene might ease the UV-related damages including age-related macular degeneration (AMD).

Assessment of the cancerization risk for oral potentially malignant disorders by clinical risk model combined with autofluorescence and brush biopsy with DNA-image cytometry.

PURPOSE: To explore the feasibility of assessing the cancerization risk of oral potentially malignant disorders (OPMD) through a clinical risk model combined with autofluorescence and brush biopsy with DNA-image cytometry. METHODS: We collected the baseline clinical data of 269 patients; then, performed autofluorescence, brush biopsy with DNA-image cytometry and histopathological examination. Then, we obtained the significant factors by univariate logistic analysis, constructed the clinical risk model by multiple logistic regression and selected the optimal cutoff value according to the maximum Youden index. Finally, we calculated the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the clinical risk score ≥ cutoff value, autofluorescence and brush biopsy with DNA-image cytometry, and plotted the receiver-operating characteristic (ROC) curves and decision curve analysis (DCA). RESULTS: The clinical risk model is represented by the formula: 1 × gender + 1.6 × age group + 1 × lesion site + 1.4 × local stimulus + 1.5 × drink. The area under the curve (AUC) was 0.83, and the optimal cutoff score was 3. The AUC indicated that the clinical risk score ≥ 3 (0.74) and autofluorescence (0.77) had a certain diagnostic values, while brush biopsy with DNA-image cytometry (0.92) displayed a good value. Besides, the DCA showed that all three tests had clinical significance. CONCLUSIONS: The cancerization risk of patients can be assessed by the clinical risk model combined with sequence application of autofluorescence and brush biopsy with DNA-image cytometry, to decide whether histopathological examination or other intervention measures should be selected.

Characterization of MK8(H2) from Rhodococcus sp. B7740 and Its Potential Antiglycation Capacity Measurements.

Menaquinone (MK) has an important role in human metabolism as an essential vitamin (VK2), which is mainly produced through the fermentation of microorganisms. MK8(H2) was identified to be the main menaquinone from Rhodococcus sp. B7740, a bacterium isolated from the arctic ocean. In this work, MK8(H2) (purity: 99.75%) was collected through a convenient and economic extraction process followed by high-speed countercurrent chromatography (HSCCC) purification. Additionally, high-resolution mass spectrometry (HRMS) was performed for further identification and the hydrogenation position of MK8(H2) (terminal unit) was determined using nuclear magnetic resonance (NMR) for the first time. MK8(H2) showed a superior antioxidant effect and antiglycation capacity compared with ubiquinone Q10 and MK4. High-performance liquid chromatography⁻mass spectrometer (HPLC-MS/MS) and molecular docking showed the fine interaction between MK8(H2) with methylglyoxal (MGO) and bull serum albumin (BSA), respectively. These properties make MK8(H2) a promising natural active ingredient with future food and medicine applications.

Antiglycation and antioxidant activities of mogroside extract from Siraitia grosvenorii (Swingle) fruits.

Siraitia grosvenorii (Swingle) is one kind of medical and edible plants with various health-promoting properties. Recently, its hypoglycemic and antidiabetic activities have been reported, but the underlying mechanism remains to be explored. The current study was aimed to investigate the antioxidant and antiglycation activities of mogroside extract (MGE) from Siraitia grosvenorii (Swingle). The results showed that compared to glycated BSA, MGE at middle (125 µg/mL) and high dose (500 µg/mL) significantly inhibited BSA glycation evidenced by decreased fluorescent AGEs formation, protein carbonyls and Nε-(carboxymethyl) lysine (CML) level at 500 µg/mL by 58.5, 26.7 and 71.2%, respectively. Additionally, the antiglycative activity of MGE (500 µg/mL) was comparable to aminoguanidine (AG) at the equal concentration. However, the inhibitory effect of MGE on glycation-induced increase of fructosamine level and decrease of thiol level was not remarkable. MGE was a potent peroxide radicals scavenger (851.8 µmol TE/g), moderate DPPH and ABTS radicals scavenger with IC50 1118.1 and 1473.2 µg/mL, respectively, corresponding to positive controls ascorbic acid of IC50 9.6 µg/mL, and trolox of IC50 47.9 µg/mL, respectively, and mild reducing power. These findings suggest that MGE may serve as a new promising antiglycative agent against diabetic complications by inhibiting protein glycation and glycoxidation.

Antisera preparation and epitope mapping of a recombinant protein comprising three peptide fragments of the cystic fibrosis transmembrane conductance regulator.

Antibodies targeting a single epitope of the cystic fibrosis transmembrane conductance regulator (CFTR) have been reported to influence the validity of immunological analyses; however, autoimmune mechanisms associated with CFTR epitopes are not well understood. In this study, antiserum raised against a multi-epitope recombinant protein composed of three peptide fragments of CFTR (r-CFTR-3P) was prepared and B cell epitope mapping of the protein was carried out using biosynthetic peptides. The r-CFTR-3P gene was cloned into the pSY621 expression plasmid and the protein was expressed in the BL21 strain of Escherichia coli. The rabbit r-CFTR-3P antiserum recognized the native CFTR antigen extracted from human sperm and the GST188 fusion peptides CFTR(25-36), CFTR(103-117), and CFTR(1387-1480) spanning different regions of CFTR. Four novel r-CFTR-3P B cell epitopes were identified: (29)RQRLEL(34), (104)RIIASY(109), (111)PDN(113), and (1447)VKLF(1450) of CFTR. Other proteins from various species shared sequence homology with the identified epitopes based on NCBI BLAST alignment. This study provides new tools for detecting CFTR protein and insight into the characteristics of minimal B cell epitopes of CFTR and associated immunological mechanisms.

AdaMotif: Graph Simplification via Adaptive Motif Design.

With the increase of graph size, it becomes difficult or even impossible to visualize graph structures clearly within the limited screen space. Consequently, it is crucial to design effective visual representations for large graphs. In this paper, we propose AdaMotif, a novel approach that can capture the essential structure patterns of large graphs and effectively reveal the overall structures via adaptive motif designs. Specifically, our approach involves partitioning a given large graph into multiple subgraphs, then clustering similar subgraphs and extracting similar structural information within each cluster. Subsequently, adaptive motifs representing each cluster are generated and utilized to replace the corresponding subgraphs, leading to a simplified visualization. Our approach aims to preserve as much information as possible from the subgraphs while simplifying the graph efficiently. Notably, our approach successfully visualizes crucial community information within a large graph. We conduct case studies and a user study using real-world graphs to validate the effectiveness of our proposed approach. The results demonstrate the capability of our approach in simplifying graphs while retaining important structural and community information.

In vitro human gut microbiota fermentation of litchi pulp polysaccharides as affected by Lactobacillus pre-treatment.

In this study, litchi polysaccharides were obtained from unfermented or fermented pulp by Lactobacillus fermentum (denoted as LP and LPF, respectively). The differences between LP and LPF in the colonic fermentation characteristics and modulatory of gut microbiota growth and metabolism were investigated with an in vitro fecal fermentation model. Results revealed that the strategies of gut bacteria metabolizing LP and LPF were different and LPF with lower molecular weight (Mw) was readily utilized by bacteria. The monosaccharide utilization sequence of each polysaccharide was Ara > Gla > GalA > GlcA ≈ Glu ≈ Man. Moreover, LPF promoted stronger proliferation of Bifidobacterium, Megamonas, Prevotella, and Bacteroides and higher SCFAs production (especially acetic and butyric acids) than LP. Correlation analysis further revealed that Mw could represent an essential structural feature of polysaccharides associated with its microbiota-regulating effect. Overall, Lactobacillus fermentation pre-treatment of litchi pulp promoted the fermentation characteristics and prebiotic activities of its polysaccharide.

Interleukin-1 receptor antagonist: a promising cytokine against human squamous cell carcinomas.

Inflammation, especially chronic inflammation, is closely linked to tumor development. As essential chronic inflammatory cytokines, the interleukin family plays a key role in inflammatory infections and malignancies. The interleukin-1 (IL-1) receptor antagonist (IL1RA), as a naturally occurring receptor antagonist, is the first discovered and can compete with IL-1 in binding to the receptor. Recent studies have revealed the association of the polymorphisms in IL1RA with an increased risk of squamous cell carcinomas (SCCs), including squamous cell carcinoma of the head and neck (SCCHN), cervical squamous cell carcinoma, cutaneous squamous cell carcinoma (cSCC), esophageal squamous cell carcinoma (ESCC), and bronchus squamous cell carcinoma. Here, we reviewed the antitumor potential of IL1RA as an IL-1-targeted inhibitor.

Modulation effect of black rice dietary fiber on the metabolism and fermentation of cyanidin-3-glucoside in an in vitro human colonic model.

Black rice (Oryza sativa L.) is a great source of anthocyanins and dietary fiber and possesses various health-promoting properties. The modulating effect of insoluble dietary fiber (IDF) from black rice on the fermentation of cyanidin-3-O-glucoside (Cy3G) in an in vitro human colonic model, together with the possible microbiota-mediated mechanisms, was investigated. The combined Cy3G and IDF fermentation can promote the biotransformation of Cy3G into phenolic compounds such as cyanidin and protocatechuic acid with stronger antioxidant activities and increase the total production of SCFAs during the fermentation of Cy3G. 16S rRNA sequencing analysis revealed that the addition of IDF modulated the microbiota structure and bloomed Bacteroidota and Prevotellaceae-related genera, which were positively correlated with metabolites of Cy3G, thus potentially regulating the microbial metabolism of Cy3G. The work is of great significance for elucidating the material basis of the health benefits of black rice.

Improved bond performances of self-etch adhesives to enamel through increased MDP-Ca salt formation via phosphoric acid pre-etching.

OBJECTIVES: The chemical affinity between 10-methacryloyloxydecyl dihydrogen phosphate (MDP) and hydroxyapatite (HAp) is an important factor in the enamel bonding provided by MDP-based self-etch (SE) adhesives, besides microinterlocking mechanisms. This study aimed to investigate how phosphoric acid pre-etching affects MDP-Ca salt formation in the application of MDP-based SE adhesives. METHODS: Single Bond Universal (SBU), All Bond Universal (ABU), Clearfil Universal Bond Quick (CBQ), and a MDP-based all-in-one adhesive (EXP) were used in both SE and etch-and-rinse (ER) modes, along with Clearfil SE Bond and untreated enamel (UE) as controls. The MDP-Ca salts produced with or without etching were examined by nuclear magnetic resonance, Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. Zeta potential, contact angle, and scanning electron microscopy measurements were employed to elucidate the mechanism behind the changes in MDP/HAp chemical affinity upon pre-etching. RESULTS: The percentage of MDP-Ca salt in EXP_ER (73.13%) was higher than that in EXP_SE (43.27%). Characteristic CH2 (1130, 1441, 2853, and 2909 cm-1), CC (1641 cm-1), and CO (1718 cm-1) bands were observed in the Raman spectra of EXP_ER. Pre-etching increased the negative zeta potential of the enamel surface compared to that of UE (P < 0.001). The contact angles of MDP-based adhesives applied to pre-etched enamel were significantly lower than those of the self-etched surface (P < 0.05). SIGNIFICANCE: The increased MDP-Ca salt formation is a significant advantage of phosphoric acid pre-etching, improving the MDP/HAp chemical affinity in addition to increasing surface wettability.