Sobrevivência em fadiga de coroas bioinspiradas bilaminadas: estudo in vitro / Fatigue survival rate of bioinspired bilaminar crowns: in vitro study

O objetivo deste estudo foi avaliar o comportamento biomecânico através da resistência à fadiga e análise por elementos finitos de coroas bioinspiradas bilaminadas com infraestruturas modificadas na superfície vestibular (Estudo A) e utilizando diferentes materiais cerâmicos com módulos elásticos distintos (Estudo B). Para isso, foram confeccionados 90 preparos para coroa total em resina epóxi G10, sobre os quais foram preparadas coroas bioinspiradas de acordo com os seguintes grupos: Estudo A - IC (infraestrutura convencional), IME (infraestrutura modificada estratificada) e IMC (infraestrutura modificada cimentada), todas confeccionadas em dissilicato de lítio (infraestrutura) + porcelana (recobrimento); Estudo B ­ DL+LEU (dissilicato de lítio + leucita), LEU+DL (leucita + dissilicato de lítio), CH+DL (cerâmica híbrida + dissilicato de lítio) e CH+LEU (cerâmica híbrida + leucita). Para o Estudo A, todas as infraestruturas foram usinadas; os recobrimentos dos grupos IC e IME foram confeccionados através da estratificação, e os recobrimentos do grupo IMC foram usinados. Já para o Estudo B, todas as peças foram usinadas, de acordo com o material cerâmico de cada grupo. Em seguida, foi realizada a cimentação adesiva dos recobrimentos sobre as infraestruturas (a depender do grupo) e das coroas sobre os preparos utilizando cimento resinoso fotopolimerizável (Variolink Esthetic LC). Após a cimentação, os espécimes foram submetidos ao teste de fadiga cíclica (10.000 ciclos, 20Hz), e como desfecho foram considerados dois eventos, em que o primeiro foi a ocorrência de trinca e/ou lascamento (evento 1) e o segundo foi a falha catastrófica do conjunto (evento 2). Os valores de carga e número de ciclos para falha em que foram observados os eventos 1 e 2 foram utilizados para realizar a análise de sobrevivência de acordo com Kaplan-Meier e Log-Rank (Mantel-Cox; 95%). As marcas de fratura e o modo de falha das coroas foram avaliados e classificados por estereomicroscópio óptico e microscópio eletrônico de varredura. Por fim, foi realizada análise por elementos finitos (FEA) para ambos os estudos, a fim de avaliar a distribuição de tensões sobre as coroas e interface adesiva. Para o Estudo A, os resultados do teste de fadiga mostraram que, considerando o evento 1 (trinca/lascamento), os grupos IC e IMC apresentaram médias de carga fadiga estatisticamente significantes entre si (733,33 N e 913,33 N, respectivamente), enquanto o grupo IME apresentou média superior (1.020 N). O mesmo foi observado para o número de ciclos em fadiga para todos os grupos. Ao considerar o evento 2 (falha catastrófica), os três grupos apresentaram médias estatisticamente semelhantes entre si (~1.028 N). Os resultados de FEA mostraram que o grupo IC concentrou maior tensão de tração do que os grupos IME e IMC. Para o Estudo B, no teste de fadiga, o grupo DL+LEU apresentou a maior média de resistência à fadiga (evento 1: 913,33 N e evento 2: 1033,33 N), enquanto todas as outras combinações de materiais cerâmicos analisadas foram estatisticamente semelhantes entre si, considerando carga e número de ciclos. Com relação ao FEA, os grupos com cerâmica híbrida (CH+DL e CH+LEU) apresentaram menores picos de concentração de tensão na infraestrutura do que os grupos com cerâmicas vítreas (DL+LEU e LEU+DL), porém, em contrapartida, concentraram maior tensão na interface adesiva. Com isso, conclui-se que a utilização da infraestrutura modificada é uma alternativa viável e promissora para tratamentos reabilitadores, apresentando sobrevivência em fadiga e distribuição de tensões satisfatórias. Além disso, a combinação entre uma infraestrutura de dissilicato de lítio e recobrimento de cerâmica a base de leucita corresponde a melhor abordagem considerando a infraestrutura modificada.(AU)

The objective of this study was to evaluate the biomechanical behavior through fatigue resistance and finite element analysis of bilaminar bioinspired crowns with modified infrastructures on the buccal surface (Study A) and using different ceramic materials with different elastic moduli (Study B). For this, 90 preparations were made for a full crown in G10 epoxy resin, on which bioinspired crowns were prepared according to the following groups: Study A - CI (conventional infrastructure), SMI (stratified modified infrastructure) and CMI (cemented modified infrastructure ), all made of lithium disilicate (infrastructure) + porcelain (veneer); Study B ­ LD+LEU (lithium disilicate + leucite), LEU+LD (leucite + lithium disilicate), HC+LD (hybrid ceramic + lithium disilicate) and HC+LEU (hybrid ceramic + leucite). For Study A, all infrastructures were machined; the coverings of the CI and SMI groups were made through stratification technique, and the veneers of the SMI group were machined. For Study B, all pieces were machined, according to the ceramic material of each group. Then, the veneers were cemented into their infrastructures (depending on the group) and crowns were cemented into preparations using light-cured resin cement (Variolink Esthetic LC). After cementing, the specimens were subjected to the cyclic fatigue test (10,000 cycles, 20Hz), and as an outcome two events were considered: the occurrence of cracking and/or chipping (event 1) and catastrophic failure (event 2). The load (N) and number of cycles to failure in which events 1 and 2 were observed were used to perform the survival analysis according to Kaplan-Meier and Log-Rank (Mantel- Cox; 95%). The fracture marks and failure mode of the crowns were evaluated and classified by optical stereomicroscope and scanning electron microscope. Finally, finite element analysis (FEA) was performed for both studies in order to evaluate the stress distribution over the crowns and adhesive interface. For Study A, the results of the fatigue test showed that, considering event 1 (cracking/chipping), the CI and CMI groups presented average to failure that were statistically significant compared to each other (733.33 N and 913.33 N, respectively), while the SMI group showed higher averages (1,020 N). Same pattern was observed for the number of cycles under fatigue for both groups. When considering event 2 (catastrophic failure), the three groups presented statistically similar means (~1,028 N). The FEA results showed that the CI group concentrated greater tensile stress than the CMI and SMI groups. For Study B, in the fatigue test, the LC+LEU group presented the highest average fatigue resistance (event 1: 913.33 N and event 2: 1033.33 N), while all other combinations of ceramic materials analyzed were statistically similar to each other, considering load and number of cycles. Regarding FEA, the groups with hybrid ceramics (HC+LC and HC+LEU) showed lower stress concentration peaks in the infrastructure than the groups with glass ceramics (LC+LEU and LEU+LC), however, on the other hand, concentrated greater tension at the adhesive interface. With this, it is concluded that the use of modified infrastructure is a viable and promising alternative for oral rehabilitation treatments, presenting satisfactory fatigue survival and adequate stress distribution. Furthermore, the combination of a lithium disilicate infrastructure and a leucite-based ceramic coating corresponds to the best approach considering the modified infrastructure.(AU)

A biomimetic nanoplatform for customized photothermal therapy of HNSCC evaluated on patient-derived xenograft models / 国际口腔科学杂志·英文版

Cancer cell membrane (CCM) derived nanotechnology functionalizes nanoparticles (NPs) to recognize homologous cells, exhibiting translational potential in accurate tumor therapy. However, these nanoplatforms are majorly generated from fixed cell lines and are typically evaluated in cell line-derived subcutaneous-xenografts (CDX), ignoring the tumor heterogeneity and differentiation from inter- and intra- individuals and microenvironments between heterotopic- and orthotopic-tumors, limiting the therapeutic efficiency of such nanoplatforms. Herein, various biomimetic nanoplatforms (CCM-modified gold@Carbon, i.e., Au@C-CCM) were fabricated by coating CCMs of head and neck squamous cell carcinoma (HNSCC) cell lines and patient-derived cells on the surface of Au@C NP. The generated Au@C-CCMs were evaluated on corresponding CDX, tongue orthotopic xenograft (TOX), immune-competent primary and distant tumor models, and patient-derived xenograft (PDX) models. The Au@C-CCM generates a photothermal conversion efficiency up to 44.2% for primary HNSCC therapy and induced immunotherapy to inhibit metastasis via photothermal therapy-induced immunogenic cell death. The homologous CCM endowed the nanoplatforms with optimal targeting properties for the highest therapeutic efficiency, far above those with mismatched CCMs, resulting in distinct tumor ablation and tumor growth inhibition in all four models. This work reinforces the feasibility of biomimetic NPs combining modular designed CMs and functional cores for customized treatment of HNSCC, can be further extended to other malignant tumors therapy.

Heterologous biomimetic synthesis of active ingredients in traditional Chinese medicine:a new mode for protection and development of traditional Chinese medicine resources / 中国中药杂志

Heterologous biomimetic synthesis of the active ingredients of traditional Chinese medicine(TCM) is a new mode of resource acquisition and has shown great potential in the protection and development of TCM resources. According to synthetic biology and by constructing biomimetic microbial cells and imitating the synthesis of active ingredients in medicinal plants and animals, the key enzymes obtained from medicinal plants and animals are scientifically designed and systematically reconstructed and optimized to realize the heterologous synthesis of the active ingredients in microorganisms. This method ensures an efficient and green acquisition of target products, and also achieves large-scale industrial production, which is conducive to the production of scarce TCM resources. Additiona-lly, the method playes a role in agricultural industrialization, and provides a new option for promoting the green and sustainable deve-lopment of TCM resources. This review systematically summarized the important progress in the heterologous biomimetic synthesis of TCM active ingredients from three research areas: biosynthesis of terpenoids, flavonoids, phenylpropanoids, alkaloids and other active ingredients, key points and difficulties in heterologous biomimetic synthesis, and biomimetic cells with complex TCM ingredients. This study facilitated the application of new generation of biotechnology and theory to the development of TCM.

Biomimetics and the restoration of the endodontically treated tooth / Biomimética e a restauração do dente tratado endodonticamente

Although much progress has been obtained in terms of the Endodontic treatment, the literature shows that true success can be only achieved with adequate coronal seal to avoid bacterial contamination, and protect the tooth structure from fracture. There are many options available to the clinician to restore the endodontically treated tooth; however, there is not much evidence available on what alternative is better than another. This review will critically present the current knowledge on restorative choices, including posts and endocrowns, showing advantages and disadvantages of different treatment forms. With this knowledge, we will also introduce the concept of biomimetics to endodontically treated teeth, and how the nature of their remaining tooth structure can benefit from this approach. This concept entails the use of mechanisms and biologically produced materials to restore a tooth in a way that would mimic its natural structure, with the purpose of achieving better long-term prognosis (AU)

Embora tenha se obtido progresso em relação ao tratamento endodôntico, a literatura mostra que o sucesso real só pode ser atingido com o selamento coronal adequado, para evitar-se a contaminação bacteriana e proteger-se a estrutura dental de fraturas. Há muitas opções disponíveis para o clínico para a restauração do dente tratado endodonticamente; entretanto, não há muita evidência disponível sobre qual alternativa é melhor que a outra. Esta revisão apresentará criticamente o conhecimento atual sobre opções restauradoras, incluindo retentores intraradiculares e endocrowns, mostrando vantagens e desvantagens das diferentes formas de tratamento. Com esse conhecimento, também introduziremos o conceito de biomimética, uma vez que dentes tratados endodonticamente, devido a natureza de sua estrutura dental remanescente, podem se beneficiar desta abordagem. Esse conceito envolve o uso de mecanismos e materiais produzidos biologicamente para restaurar um dente de forma a imitar a estrutura natural, com o objetivo de alcançar melhor prognóstico de longo-prazo.(AU)

The Influence of the Shoe over the Medial Foot Arch and the Lower Limbs Kinematics in Toddlers / A influência de calçados no arco longitudinal medial do pé e na cinemática dos membros inferiores de crianças no início da fase de aquisição de marcha

Abstract Objective To evaluate the biomechanical behavior of the medial longitudinal arch (MLA) of the foot and the kinematic parameters of the lower limbs with biomimetic footwear (BF) and non-biomimetic (NB1, NB2, NB3 and NB4) footwear in children at the beginning of the gait acquisition phase. Methods Four toddlers were evaluated at the beginning of the gait acquisition phase under the following conditions: walking barefoot, ambulation with BF and NB1, NB2, NB3 and NB4 footwear in hard floor. BF is described as biomimetic because of its property of emulating natural and irregular floors through a dynamic internal insole. The MLA and kinematics of the hip, knee, and ankle during gait were evaluated by three-dimensional motion analysis system. The similarity between the kinematic curves of barefoot and footwear conditions was analyzed by root mean square error (RMSE). Results The use of BF presented the highest magnitude of MLA and the greatest difference in relation to barefoot condition (higher RMSE). The BF showed less difference in the kinematics of the knee and ankle joints during gait when compared to barefoot condition (lower RMSE). NB2 footwear presented hip kinematics more similar to barefoot condition (lower RMSE). Conclusion Biomimetics footwear and NB2 shoes (both with wider forefoot region) generated smaller differences in lower limbs compared to barefoot. In addition, the MLA was higher in the BF, probably because different design from other shoes.

Resumo Objetivo Avaliar o comportamento do arco longitudinal medial do pé (ALM) e os parâmetros cinemáticos dos membros inferiores durante a deambulação com calçados biomiméticos (CBs) e não biomiméticos (NB1, NB2, NB3 e NB4) em crianças no início da fase de aquisição da marcha. Métodos Foram avaliadas quatro crianças no início da fase de aquisição da marcha nas seguintes condições: andar descalço, andar com CBs e calçados NB1, NB2, NB3 e NB4 em solo plano. O calçado biomimético é descrito como biomimético por emular pisos naturais e irregulares por meio de uma palmilha interna dinâmica. O ALM e a cinemática do quadril, joelho e tornozelo durante a marcha foram avaliados por meio de sistema de análise do movimento tridimensional. A similaridade entre as curvas cinemáticas das condições descalça e com calçado foi analisada por meio do cálculo de root mean square error (RMSE). Resultados O CB foi o que apresentou maior magnitude do ALM e maior diferença do ALM em relação à condição descalça (maior RMSE). O CB apresentou ainda menor diferença na cinemática das articulações do joelho e tornozelo durante a marcha quando comparado à condição descalça (menor RMSE). O calçado NB2 apresentou a cinemática do quadril mais semelhante à condição descalça (menor RMSE). Conclusão Os calçados CB e NB2 que apresentam a região do antepé mais larga geraram menores diferenças na cinemática dos membros inferiores. Além disso, o ALM foi maior no CB provavelmente devido a seu design ser diferente daquele dos demais calçados.

Role of biomimetic nanomaterials made from glioma cell- derived extracellular vesicles in targeted delivery of STAT3-siRNA / 中南大学学报(医学版)

OBJECTIVES@#Glioma is the most common primary intracranial tumor and there is still no ideal treatment at present. Gene therapy, as one of the new methods for treating glioma, has attracted attention in recent years. But its application in treating glioma is very limited due to lack of effective delivery vectors. This study aims to investigate the feasibility of biomimetic nanomaterials made from glioma cells-derived extracellular vesicles (EV) for targeted delivery of signal transducers and activators of transcription 3 (STAT3)-small interfering RNA (siRNA) in treating glioma.@*METHODS@#First, U251 glioma cells-derived extracellular vessel (EVU251) was extracted by ultra-centrifugal method. Nanoparticle tracking analysis was used to characterize the particle size distribution, the transmission electron microscope was used to analyze the morphology, and Western blotting was used to verify the expression of srface characteristic protein. The homing ability was verified by cell uptake assay after labeling EVU251 with membrane dye kit PKH67; the EVU251 contents were removed by a low permeability method and then EVMU251 was prepared through a microporous membrane. Finally, the biomimetic nanomaterials EVMU251@STAT3-siRNA were prepared by loading STAT3-SiRNA with electro-dyeing method. The real-time quantitative PCR was used to quantify the successful encapsulation of siRNA, and the encapsulation and drug loading rate was calculated; then Cy5-labeled siRNA was used to evaluate the ability of biomimetic nanomaterials (EVMU251@CY5-siRNA) to target U251 cells. Lysosomal escape ability of the biomimetic nanomaterial was evaluated by lysosomal dye lyso-tracker green. At last, the ability of EVMU251@STAT3-siRNA to knock down STAT3 gene and selective killing of U251 cells was detected by cell experiments in vitro.@*RESULTS@#The size of EVU251 ranged from 50 nm to 200 nm with a natural disc shape. The expression of extracellular vesicle marker proteins could be detected on the membrane of EVU251. The cell uptake assay demonstrated that it had homing ability to target U251 cells. After EVU251 was prepared as EVMU251@STAT3-siRNA, the particle size was (177.9±5.0) nm, the siRNA loading rate was (33.5±2.2)% and the drug loading rate was (3.24±0.21)%. The biomimetic nanomaterial EVMU251@STAT3-siRNA still had the ability to target U251 cells and successfully deliver siRNA to the cytoplasm without lysosomal degradation. The EVMU251@STAT3-siRNA can effectively knock down the expression of STAT3 gene and produce selective killing ability in U251 cells.@*CONCLUSIONS@#The biomimetic nanomaterials EVMU251@STAT3-siRNA made from glioma U251 cells-derived extracellular vesicles can knock down STAT3 gene of U251 cells and produce selective killing effect, which can provide a new idea for the treatment of glioma.

Advances in researches on enamel biomimetic mineralization / 中华口腔医学杂志

Dental enamel biomimetic mineralization is a process to form the enamel-like mineral structures, which possess unique microstructure and exceptional physic-chemical properties, by mimicking the mechanism of natural enamel formation and biomineralization. Varieties of techniques such as molecular mimetic synthesis and molecular self-assembling were used to accomplish the microenvironment and molecular conditions similar to that of natural tooth enamel within human body. Early remineralization and biomineralization is the future of restoration for enamel defect, research on such products have huge potential in clinical applications, with speedy advancement in recent two decades. This review summarizes the major advances in researches on enamel biomimetic mineralization in recent years.

Early efficacy of three dimensional printed anatomical biomimetic cervical artificial disc replacement in the treatment of cervical degenerative diseases / 中华外科杂志

Objective: To investigate the efficacy and safety of a new cervical artificial disc prosthesis in the treatment of cervical degenerative diseases. Methods: The clinical data of 18 patients with single-level cervical degenerative diseases who underwent three dimensional printed anatomical bionic cervical disc replacement at Department of Spinal Surgery,Honghui Hospital,Xi'an Jiaotong University from May 2019 to July 2020 were analyzed retrospectively. There were 7 males and 11 females,aged (45±8) years old(range:28 to 58 years).The surgical segment was located at C3－4 level in 2 cases, C4－5 level in 5 cases, C5－6 level in 9 cases, and C6－7 level in 2 cases.The clinical and radiographic outcomes were recorded and compared at preoperative,postoperative times of one month and twelve months.The clinical assessments contained Japanese orthopedic association (JOA) score,neck disability index (NDI) and visual analogue scale (VAS).Imaging assessments included range of motion (ROM) of cervical spine, prosthesis subsidence and prosthesis anteroposterior migration.Repeated measurement variance analysis was used for comparison between groups,and paired t test was used for pairwise comparison. Results: All patients underwent the operation successfully and were followed up for more than 12 months.Compared with preoperative score,the JOA score,NDI and VAS were significantly improved after surgery (all P<0.01).There was no significant difference in postoperative ROM compared with 1-and 12-month preoperative ROM (t=1.570,P=0.135;t=1.744,P=0.099). The prosthesis subsidence was (0.29±0.13) mm (range: 0.18 to 0.50 mm) at 12-month postoperatively.The migration of prosthesis at 12-months postoperatively were (0.71±0.20) mm (range: 0.44 to 1.08 mm).There was no prosthesis subsidence or migration>2 mm at 12-month postoperatively. Conclusion: Three dimensional printed anatomical biomimetic cervical artificial disc replacement has a good early clinical effect in the treatment of cervical degenerative diseases, good mobility can be obtained while maintaining stability.

Application of biomimetic restoration in oral-maxillofacial hard tissue repair / 华西口腔医学杂志

Oral-maxillofacial hard tissue is the support of maxillofacial structure and appearance, and lays the foundation for functions of oral and maxillofacial system. Once the defect occurs, it will not only affect the physiological functions such as chewing and pronunciation, but also have a significant impact on the psychological and social life of patients. However, the self-repairing capability of the oral-maxillofacial hard tissue is pretty limited, in which case, substitute materials are required for tissue repair. A huge gap exists between the physical, chemical, structural characteristics of conventional substitute materials and those of human hard tissues, resulting in poor repair effect. Based on this, scholars simulated the process of biomineralization in the development of hard tissues, to improve the structure and function of materials through biomimetic mineralization technology and enhance the repair performance of materials. The current understanding of biomineralization theory and the construction of biomimetic repair technology is still in the stage of rapid development. In recent years, a mass of innovative studies are keeping emerging. In this review, the representative advances in the repair of oral-maxillofacial hard tissues of the past five years are reviewed.

Advances in biomimetic modification of materials for oromaxillofacial bone regeneration and dental implant / 华西口腔医学杂志

Oromaxillofacial hard tissue defects is still a difficult problem in clinical treatment. Regeneration of oromaxillofacial hard tissue based on tissue engineering technology has a good clinical application prospect. The functional modification of scaffolds is one of key factors that influence the outcome of tissue regeneration. The biomimetic design of biomaterials through simulating the natural structure and composition of oromaxillofacial hard tissue has gradually become a research hotspot due to its advantages of simplicity and efficiency. In this article, the biomimetic modification of biomaterials for oromaxillofacial hard tissue regeneration is reviewed, expecting to provide a new idea for the treatment of oromaxillofacial hard tissue defect.

Lipophilicity Descriptors Correlate Uniquely with Pharmacokinetic and Blood-Brain Barrier Penetration Parameters for Selected Antipsychotic Drugs

Lipophilicity is an important physicochemical parameter of biological relevance; although its in- vivo predictive capability is dependent on accuracy and reliability of platforms used for its determination. This work examines biomimetic attribute of isocratic chromatographic hydrophobicity index (ICHI), experimental logarithm of octanol ­ water partition coefficient (LogP) and some computed lipophilicity indices for eight (8) selected antipsychotic agents and their predictive capability in drug discovery. The retention behavior of 5 first-generation and 3 second-generation antipsychotics was determined on reversed-phase chromatographic platform using methanol-phosphate buffer (pH 6.8) mobile phase. The retardation factor obtained was transformed to Rm, and plotted against volume fraction of organic modifier in the mobile phase to generate linear graph whose x- intercept is ICHI. Experimental LogP values were curled from literature while computed LogP were obtained using respective software. The experimentally determined LogPoctanol/water and ICHI were first correlated with index of brain permeability (BBB); before all lipophilicity indices were comparatively evaluated and correlated with in-vivo-normalized pharmacokinetic parameters curled from literature. ICHI gave better correlation with BBB index (r = 0.976) compared to Log Poctanol/water (r = 0.557). Comparative lipophilicity evaluation shows clustered pattern for second generation antipsychotics compared to first generation. In vivo correlation was poorer for the 8 drugs (r < 0.7), better with subset of phenothiazine homologues (r = 0.51 to 0.97). The ALogP, LogPoctanol/water, cLogP and ICHI gave highest correlation with the pharmacokinetic parameters. The biomimetic attributes of ICHI is better than for LogPoctanol/water in predicting brain permeability, but lower for in-vivo pharmacokinetic prediction.

Effect of Using Biomimetic Analogs on Dentin Remineralization with Bioactive Cements

Abstract This study evaluated the impact of using biomimetic analogs (poly-acrylic acid and sodium tri-meta-phosphate) on dentin remineralization using two cement materials, the first is calcium silicate based and the second is calcium hydroxide based materials. Two standardized occlusal cavities (mesial and distal) were prepared within dentin after removal of occlusal enamel. Artificial demineralized dentin was induced through pH cycling (8 h in demineralizing and 16 h in remineralizing solutions). Demineralized cavities were divided into four groups; two groups received cement materials. The other groups were first treated with biomimetic analogs then restored with pulp cement materials. Teeth were sectioned buccolingually into two halves. Treated cavities with analogs were stored in simulated body fluid containing poly-acrylic acid. Untreated cavities were stored in simulated body fluid only. Ground unstained sections of demineralized dentin were examined using light microscope. Specimens were examined after 1, 6 and 12 weeks of storage using energy dispersive X-ray Spectroscopy (EDX) and Vickers microhardness was evaluated. Two-way ANOVA was used to analyze data statistically. Calcium silicate-based cement group with biomimetic analogs showed the highest statistically significant calcium and phosphorous wt% in addition to highest surface hardness values after 12 weeks of storage. Demineralized dentin ground sections showed increase in light zones after total period of storage. Calcium silicate-based cement showed the best ability to enrich the artificial carious dentin with ions for remineralization. Using biomimetic analogs had a significant impact on demineralized dentin surface hardness improvement.

Resumo Este estudo avaliou o impacto do uso de análogos biomiméticos (ácido poli-acrílico e tri-meta-fosfato de sódio) na remineralização da dentina usando dois materiais de cimento, o primeiro à base de silicato de cálcio e o segundo à base de hidróxido de cálcio. Duas cavidades oclusais padronizadas (mesial e distal) foram preparadas na dentina após a remoção do esmalte oclusal. A dentina desmineralizada artificial foi induzida por ciclagem de pH (8 h em soluções desmineralizantes e 16 h em soluções remineralizantes). Cavidades desmineralizadas foram divididas em quatro grupos; dois grupos receberam materiais de cimento. Os outros grupos foram tratados primeiro com análogos biomiméticos e depois restaurados com materiais de cimento de celulose. Os dentes foram seccionados bucolingualmente em duas metades. As cavidades tratadas com análogos foram armazenadas em fluido corporal simulado contendo ácido poli-acrílico. As cavidades não tratadas foram armazenadas apenas em fluido corporal simulado. Secções não coradas de dentina desmineralizada foram examinadas usando microscópio óptico. As amostras foram examinadas após 1, 6 e 12 semanas de armazenamento usando Espectroscopia de Raios-X dispersiva por energia (EDX) e microdureza Vickers. ANOVA a dois fatores foi usada para analisar os dados estatisticamente. O grupo de cimento à base de silicato de cálcio com análogos biomiméticos apresentou os maiores percentagens em peso estatisticamente significantes de cálcio e fósforo, além dos maiores valores de dureza superficial após 12 semanas de armazenamento. Seções desmineralizadas de dentina mostraram aumento nas zonas de luz após o período total de armazenamento. O cimento à base de silicato de cálcio mostrou a melhor capacidade de enriquecer a dentina cariada artificial com íons para remineralização. O uso de análogos biomiméticos teve um impacto significativo na melhoria da dureza superficial da dentina desmineralizada.

Macrophage-derived small extracellular vesicles promote biomimetic mineralized collagen-mediated endogenous bone regeneration / 国际口腔科学杂志·英文版

Macrophages play an important role in material-related immune responses and bone formation, but the functionality of macrophage-derived extracellular vesicles (EVs) in material-mediated bone regeneration is still unclear. Here, we evaluated intracellular communication through small extracellular vesicles (sEVs) and its effects on endogenous bone regeneration mediated by biomimetic intrafibrillarly mineralized collagen (IMC). After implantation in the bone defect area, IMC generated more neobone and recruited more mesenchymal stem cells (MSCs) than did extrafibrillarly mineralized collagen (EMC). More CD63

Research progress on the biomimetic remineralization of hard tooth tissues based on polyamide-amine dendrimer / 华西口腔医学杂志

Polyamide-amine (PAMAM) dendrimer, a new hyperbranched macromolecular polymer, is considered an "artificial protein" by many scholars on account of its excellent chemical and biological characteristics. PAMAM has internal cavities and a large number of reactive terminal groups. These structures allow the polymer to be used as a bionic macromoleculethat could simulate the biomimetic mineralization of the natural organic matrix on the surface of tooth tissue. Specifically, PAMAM can beused as an organic template to regulate mineral nucleation and crystal growth; thus, the polymerisa more ideal dental restoration material than traditional allogenic materials. This article reviews research progress on thePAMAM-induced biomimetic mineralization of hard tooth tissues.

Biological Restorations: A foreseeable possibility in the junction between dentistry and technology / Restaurações Biológicas: Uma possibilidade previsível no encontro da Odontologia com a Tecnologia

Prosthetic rehabilitation can generate doubts among professionals regarding the type of material to choose when planning rehabilitation treatments. The establishment of reliable criteria for material selection raises frequent questions. This work presents a concept and an alternative and simplified proposal to paradigm shift in therapeutic approaches based on three trends in restorative dentistry: Biomimetics, the use of natural tissue as a restorative material, which offers potential for the recovery of the mechanical, aesthetic and biological properties of teeth; digital dentistry and CAD/CAM systems; and adhesive technology, which has undergone exponential and impressive advances. However, further studies are needed to evaluate the long-term performance of restorations in this variable field. (AU)

Muitas dúvidas surgem quanto ao tipo ideal de material restaurador a ser escolhido durante a elaboração do planejamento em tratamentos reabilitadores. Determinar critérios seguros para seleção do material são questionamentos frequentes. Este trabalho apresenta, por meio de um caso clínico, um conceito: restaurações biológicas e uma proposta alternativa e simplificada para quebrar paradigmas quanto a novas abordagens terapêuticas com as três tendências da Odontologia Restauradora Moderna: Biomimética ­ mimetizar e/ou utilizar o tecido natural dental como o material restaurador, com potencial de recuperar as propriedades mecânicas, estéticas e biológicas dos dentes danificados, a Odontologia digital e Sistemas CAD/CAM - com avanços exponenciais e a consagrada tecnologia adesiva. Porém mais estudos ainda são necessários para avaliar o desempenho a longo prazo dessas restaurações neste vasto campo de variabilidades. (AU)

Enamel biomimetics-fiction or future of dentistry / 国际口腔科学杂志·英文版

Tooth enamel is a complex mineralized tissue consisting of long and parallel apatite crystals configured into decussating enamel rods. In recent years, multiple approaches have been introduced to generate or regenerate this highly attractive biomaterial characterized by great mechanical strength paired with relative resilience and tissue compatibility. In the present review, we discuss five pathways toward enamel tissue engineering, (i) enamel synthesis using physico-chemical means, (ii) protein matrix-guided enamel crystal growth, (iii) enamel surface remineralization, (iv) cell-based enamel engineering, and (v) biological enamel regeneration based on de novo induction of tooth morphogenesis. So far, physical synthesis approaches using extreme environmental conditions such as pH, heat and pressure have resulted in the formation of enamel-like crystal assemblies. Biochemical methods relying on enamel proteins as templating matrices have aided the growth of elongated calcium phosphate crystals. To illustrate the validity of this biochemical approach we have successfully grown enamel-like apatite crystals organized into decussating enamel rods using an organic enamel protein matrix. Other studies reviewed here have employed amelogenin-derived peptides or self-assembling dendrimers to re-mineralize mineral-depleted white lesions on tooth surfaces. So far, cell-based enamel tissue engineering has been hampered by the limitations of presently existing ameloblast cell lines. Going forward, these limitations may be overcome by new cell culture technologies. Finally, whole-tooth regeneration through reactivation of the signaling pathways triggered during natural enamel development represents a biological avenue toward faithful enamel regeneration. In the present review we have summarized the state of the art in enamel tissue engineering and provided novel insights into future opportunities to regenerate this arguably most fascinating of all dental tissues.

Mining and engineering of microbial carbonic anhydrases for biomimetic carbon dioxide sequestration / 生物工程学报

The increasing atmospheric carbon dioxide levels have been correlated with global warming. Carbonic anhydrases (CA) are the fastest among the known enzymes to improve carbon capture. The capture of carbon dioxide needs high temperature and alkaline condition, which is necessary for CaCO₃ precipitation in the mineralization process. In order to use CAs for biomimetic carbon sequestration, thermo-alkali-stable CAs are, therefore, essential, and polyextremophilic microbes are one of the important sources of these enzymes. The current review focuses on both those isolated by thermophilic organisms from the extreme environments and those obtained by protein engineering techniques, and the industrial application of the immobilized CAs is also briefly addressed. To reduce the greenhouse effect and delay global warming, we think further research efforts should be devoted to broadening the scope of searching for carbonic anhydrase, modifying the technology of protein engineering and developing highly efficient immobilization strategies.

Application of adhesive materials in biomedicine: progress and prospects / 生物工程学报

As an important auxiliary material, adhesive materials have many important applications in various fields including but not limited to industrial packaging, marine engineering, and biomedicine. Naturally occurring adhesives such as mussel foot proteins are usually biocompatible and biodegradable, but their limited sources and poor mechanical properties in physiological conditions have limited their widespread uses in biomedical field. Inspired by the underwater adhesion phenomenon of natural organisms, a series of biomimetic adhesive materials have been developed through chemical or bioengineering approaches. Notably, some of those synthetic adhesives have exhibited great promise for medical applications in terms of their biocompatibility, biodegradability, strong tissue adhesion and many other attractive functional properties. As natural adhesive materials possess distinctive "living" attributes such as environmental responsiveness, self-regeneration and autonomous repairs, the development of various biologically inspired and biomimetic adhesive materials using natural adhesives as blueprints will thus be of keen and continuous interest in the future. The emerging field of synthetic biology will likely provide new opportunities to design living glues that recapitulate the dynamic features of those naturally occurring adhesives.

Hybrid Additive Microfabrication Scaffold Incorporated with Highly Aligned Nanofibers for Musculoskeletal Tissues

BACKGROUND: Latest tissue engineering strategies for musculoskeletal tissues regeneration focus on creating a biomimetic microenvironment closely resembling the natural topology of extracellular matrix. This paper presents a novel musculoskeletal tissue scaffold fabricated by hybrid additive manufacturing method. METHODS: The skeleton of the scaffold was 3D printed by fused deposition modeling, and a layer of random or aligned polycaprolactone nanofibers were embedded between two frames. A parametric study was performed to investigate the effects of process parameters on nanofiber morphology. A compression test was performed to study the mechanical properties of the scaffold. Human fibroblast cells were cultured in the scaffold for 7 days to evaluate the effect of scaffold microstructure on cell growth. RESULTS: The tip-to-collector distance showed a positive correlation with the fiber alignment, and the electrospinning time showed a negative correlation with the fiber density. With reinforced nanofibers, the hybrid scaffold demonstrated superior compression strength compared to conventional 3D-printed scaffold. The hybrid scaffold with aligned nanofibers led to higher cell attachment and proliferation rates, and a directional cell organization. In addition, there was a nonlinear relationship between the fiber diameter/density and the cell actinfilament density. CONCLUSION: This hybrid biofabrication process can be established as a highly efficient and scalable platform to fabricate biomimetic scaffolds with patterned fibrous microstructure, and will facilitate future development of clinical solutions for musculoskeletal tissue regeneration.

Biomimetic characteristics of mussel adhesive protein-loaded collagen membrane in guided bone regeneration of rabbit calvarial defects

PURPOSE: The aim of the present study was to evaluate the biocompatibility and barrier function of mussel adhesive protein (MAP)-loaded collagen membranes in guided bone regeneration (GBR). METHODS: Eight male New Zealand white rabbits were used. Four circular defects (diameter: 8 mm) were created in the calvarium of each animal. The defects were randomly assigned to 1) a negative control group, 2) a cyanoacrylate (CA)-loaded collagen membrane group (the CA group), 3) a MAP-loaded collagen membrane group (the MAP group), and 4) a group that received a polycaprolactone block with MAP-loaded collagen membrane (the MAP-PCL group). Specimens were harvested at 2 weeks (n=4) and 8 weeks (n=4) postoperatively for observational histology and histometric analysis. RESULTS: In the histologic analysis, MAP was completely absorbed without any byproducts. In contrast, some of the CA adhesive remained, showing an inflammatory reaction, at 8 weeks. In the MAP-PCL group, the MAP-loaded collagen membranes served as a barrier membrane despite their fast degradation in GBR. No significant difference was found in the amount of new bone between the MAP-PCL and MAP groups (1.82±0.86 mm2 and 2.60±0.65 mm2, respectively). CONCLUSIONS: The MAP-loaded collagen membrane functioned efficiently in this rabbit calvarial GBR model, with excellent biocompatibility. Further research is needed to assess clinical applications in defect types that are more challenging for GBR than those used in the current model.