Physicomechanical properties of the extracellular matrix of a demineralized bone

The article describes the results of a study of physicomechanical properties of a demineralized bone matrix of human cancellous and compact bones. A demineralized cancellous bone was shown to have the best characteristics of a porous system for colonization of matrices by cells. The ultimate stress and elasticity modulus of samples of demineralized femoral heads isolated in primary hip replacement was demonstrated to vary in wide ranges. The elasticity modulus ranged from 50 to 250 MPa, and the tensile strength varied from 1.1 to 5.5 MPa. Microhardness measurements by the recovered indentation method were not possible because of the viscoelastic properties of a bone material. To study the piezoelectric properties of samples, a measuring system was developed that comprised a measuring chamber with contact electrodes, a system for controlled sample loading, an amplifier-converter unit, and signal recording and processing software. The measurement results were used to determine the dependence of the signal amplitude on the dynamic deformation characteristics. The findings are discussed in terms of the relationship between the mechanical and electrical properties and the structure of the organic bone component

Physicomechanical properties of the extracellular matrix of a demineralized bone

The article describes the results of a study of physicomechanical properties of a demineralized bone matrix of human cancellous and compact bones. A demineralized cancellous bone was shown to have the best characteristics of a porous system for colonization of matrices by cells. The ultimate stress and elasticity modulus of samples of demineralized femoral heads isolated in primary hip replacement was demonstrated to vary in wide ranges. The elasticity modulus ranged from 50 to 250 MPa, and the tensile strength varied from 1.1 to 5.5 MPa. Microhardness measurements by the recovered indentation method were not possible because of the viscoelastic properties of a bone material. To study the piezoelectric properties of samples, a measuring system was developed that comprised a measuring chamber with contact electrodes, a system for controlled sample loading, an amplifier-converter unit, and signal recording and processing software. The measurement results were used to determine the dependence of the signal amplitude on the dynamic deformation characteristics. The findings are discussed in terms of the relationship between the mechanical and electrical properties and the structure of the organic bone component

Phase Composition and Microstructure of Ti-Nb Alloy Produced by Selective Laser Melting

The phase composition and microstructure of Ti-Nb alloy produced from composite titanium and niobium powder by selective laser melting (SLM) was studied. Produced monolayered Ti-Nb alloy enhanced the formation of fine-grained and medium-grained zones with homogeneous element composition of 36-38% Nb mass interval. Alloy phase composition responded to [beta]-alloy substrate phase (grain size was 5-7 pm) and non-equilibrium martensite [alpha]"- phase (grain size was 0.1-0.7 [mu]m). [alpha]"-phase grains were found along [beta]-phase grain boundaries and inside grains, including decreased niobium content. Alloy microhardness varied within 4200-5500 MPa

Properties of the "Orgamax" osteoplastic material made of a demineralized allograft bone

We investigated properties of the “Orgamax” osteoplastic material, which was produced from a demineralized bone, in the treatment of extensive caries, in particular chronic pulpitis of the permanent teeth with unformed roots in children. The “Orgamax” osteoplastic material consists of demineralized bone chips, a collagen additive, and antibiotics. The surface morphology of the “Orgamax” osteoplastic materialis macroporous, with the maximum pore size of 250 [mu]m, whereas the surface morphology of the major component of “Orgamax”, demineralized bone chips, is microporous, with a pore size of 10-20 [mu]m. Material “Orgamax” is used in the treatment of complicated caries, particularly chronic pulpitis of permanent teeth with unformed roots in children. “Orgamax” filling a formed cavity exhibits antimicrobial properties, eliminates inflammation in the dental pulp, and, due to its osteoconductive and osteoinductive properties, undergoes gradual resorption, stimulates regeneration, and provides replacement of the defect with newly formed tissue. The dental pulp viability is completely restored, which ensures the complete formation of tooth roots with root apex closure in the long-term period

СВОЙСТВА ДЕМИНЕРАЛИЗОВАННОГО КОСТНОГО МАТРИКСА ДЛЯ БИОИНЖЕНЕРИИ ТКАНЕЙ

The purpose. Determination of tissues of physico-mechanical properties of demineralized bone matrix of spongy and compact human bone important for bioengineering.Material and Methods.The methods for studying micromorphological, piezoelectric and transport properties, adapted for measuring the materials of potential scaffolds.Results. The results of studying the physico-mechanical properties of the demineralized bone matrix of spongy and compact human bones are presented. It is shown that the demineralized spongy bone possesses the best characteristics of the pore system for the colonization of matrix cells. The tensile strength and modulus of elasticity of samples from the demineralized heads of the femurs extracted during the initial hip arthroplasty vary widely. The modulus of elasticity varied from 50 to 250 MPa, and the ultimate strength was from 1.1 to 5.5 MPa.Conclusion. Methods for measuring micromorphological, piezoelectric and transport properties for materials of potential matrices were developed and / or adapted. It is shown that in the samples of materials from the human bone, these characteristics, as a rule, vary considerably. Proceeding from this, it becomes obvious that the development of protocols of measurement methods of the above listed properties is an important work for the creation of technology of bioengineering of tissue implants for reconstructive surgery. Цель. Определение значимых для биоинженерии тканей физико-механических свойств деминерализованного костного матрикса губчатой и компактной кости человека.Материалы и методы. Перечислены методы исследования микроморфологических, пьезоэлектрических и транспортных свойств, адаптированные для измерения у материалов потенциальных матриц.Результаты. Приведены результаты исследования физико-механических свойств деминерализованного костного матрикса губчатой и компактной кости человека. Показано, что деминерализованная губчатая кость обладает наилучшими характеристиками поровой системы для заселения матриксов клетками. Предел прочности и модуль упругости образцов из деминерализованных головок бедренных костей, извлеченных в ходе первичного эндопротезирования тазобедренного сустава, изменяются в широких пределах. Модуль упругости изменялся от 50 до 250 МПа, а предел прочности – от 1,1 до 5,5 МПа.Заключение. Были отработаны и/или адаптированы методы измерений микроморфологических, пьезоэлектрических и транспортных свойств у материалов потенциальных матриц. Показано, что у образцов материалов из кости человека данные характеристики, как правило, значительно варьируют. Исходя из этого, становится очевидным, что отработка протоколов методов измерения вышеперечисленных свойств является важной работой для создания технологии биоинженерии тканевых имплантатов для восстановительной хирургии.

Влияние продолжительности термической обработки на структуру и фазовый состав образцов сплава Co-Cr-Mo, полученных с помощью аддитивных технологий

Laser powder bed fusion (LPBF) requires application of powders with specific characteristics. These are near-spherical shape of particles, uniform elemental composition, typical particle size of 5 - 70 mu m, etc. Such powders are produced by spheroidization methods. They have such disadvantages as high cost and sale only in large quantities. There are publications describing application in LPBF powders, produced by the methods, alternative to spheroidiz,ation. In the current study, powders of pure raw Co, Cr and Mo were used for the production of Co-Cr-Mo powder mixture. Samples of Co-28 wt.% Cr-6 wt.% Mo alloy were produced by LPBF from this powder mixture. Due to the difference between melting temperatures of Co, Cr and Mo, inclusions of Cr and Mo were formed within the bulk of samples. Studies of phase and elemental composition, structure and microhardness of the as-produced samples and after post-treatment with varied duration are represented. As-produced samples have non-uniform elemental composition and are represented by the main Co-based phase. Increasing the annealing duration leads to the sequential dissolution of un-melted Cr and Mo inclusions. Complete dissolution of Cr particles was observed at 10 hours of treatment and complete dissolution of Mo particles was not observed after 20 hours of annealing. Microhardness non-linearly changes with the increasing duration of annealing. This is due to the phase transformations and diffusion processes occurring at such type of post-treatment. Complete dissolution of Mo-particles could be achieved by further increasing the annealing time or by varying the mode of laser powder bed fusion

Enhanced Corrosion Resistance and Mechanical Durability of the Composite PLGA/CaP/Ti Scaffolds for Orthopedic Implants

In addressing the challenge of enhancing orthopedic implants, 3D porous calcium phosphate (CaP) coatings on titanium (Ti) substrates modified with poly(lactic-co-glycolic acid) (PLGA) were proposed. CaP coatings on Ti were deposited using the ultrasonic-assisted micro-arc oxidation (UMAO) method, followed by modification with PLGA through a dip coating process at concentrations of 5%, 8%, and 10%. The addition of PLGA significantly improved adhesive–cohesive strength according to the scratch test, while PLGA to CaP adhesion was found to be not less than 8.1 ± 2.2 MPa according to the peel test. Tensile testing showed a typical fracture of CaP coatings and mechanisms of brittle fracture. Corrosion resistance, assessed via gravimetric and electrochemical methods in 0.9% NaCl and PBS solutions, revealed PLGA’s substantial reduction in corrosion rates, with the corrosion current decreasing by two orders of magnitude even for the 5% PLGA/CaP/Ti sample. Also, the PLGA layer significantly enhanced the impedance modulus by two orders of magnitude, indicating a robust barrier against corrosion at all PLGA concentrations. Higher PLGA concentrations offered even greater corrosion resistance and improved mechanical properties. This research underscores the potential of using CaP- and PLGA-modified coatings to extend the life and functionality of orthopedic implants, addressing a significant challenge in biomedical engineering