Influence of pH on morphology, size and polymorph of room temperature synthesized calcium carbonate particles

Calcium carbonate (CaCO3) particles have been used in various applications, including medicine, drug delivery and orthopedics. Having three different polymorphs and exhibiting complex crystallization behavior, it is a challenging task to systematically control physical properties of CaCO3 particles for desired applications. Herein, the influence of pH and [Ca2+]:[CO32-] ratio on the morphology, size and polymorph of room temperature synthesized CaCO3 particles were investigated. Although, in literature, ethylene glycol concentration of precursor solutions is considered as one of the most critical factors controlling polymorph and morphology of CaCO3 particles, present work highlights precursor solution pH to be a stronger factor in controlling room temperature synthesized CaCO3 particle properties. In fact, CaCO3 particle size decreased from micron to sub-micron range and calcite polymorph transformed to vaterite upon decreasing pH of the precursors for all of the precursor solution [Ca2+]:[CO32-] ratios investigated in this study. Importantly, CaCO3 particles with different and distinct morphologies were obtained by altering pH and [Ca2+]:[CO32-] ratios of the precursor solutions. Since requirements for the physical properties of CaCO3 particles are diverse for industrial and medical applications, it is important to understand CaCO3 crystallization behavior for tailored particle synthesis

In vivo applications of micro/nanorobots

Untethered robots in the size range of micro/nano-scale offer unprecedented access to hard-to-reach areas of the body. In these challenging environments, autonomous task completion capabilities of micro/nanorobots have been the subject of research in recent years. However, most of the studies have presented preliminary in vitro results that can significantly differ under in vivo settings. Here, we focus on the studies conducted with animal models to reveal the current status of micro/nanorobotic applications in real-world conditions. By a categorization based on target locations, we highlight the main strategies employed in organs and other body parts. We also discuss key challenges that require interest before the successful translation of micro/nanorobots to the clinic.Web of Science15198507849

Hybrid enzymatic/photocatalytic degradation of antibiotics via morphologically programmable light-driven ZnO microrobots

Antibiotics are antimicrobial substances that can be used for preventive and therapeutic purposes in humans and animals. Their overdose usage has led to uncontrolled release to the environment, contributing significantly to the development of antimicrobial resistance phenomena. Here, enzyme-immobilized self-propelled zinc oxide (ZnO) microrobots are proposed to effectively target and degrade the released antibiotics in water bodies. Specifically, the morphology of the microrobots is tailored via the incorporation of Au during the synthetic process to lead the light-controlled motion into having on/off switching abilities. The microrobots are further modified with laccase enzyme by physical adsorption, and the immobilization process is confirmed by enzymatic activity measurements. Oxytetracycline (OTC) is used as a model of veterinary antibiotics to investigate the enzyme-immobilized microrobots for their removal capacities. The results demonstrate that the presence of laccase on the microrobot surfaces can enhance the removal of antibiotics via oxidation. This concept for immobilizing enzymes on self-propelled light-driven microrobots leads to the effective removal of the released antibiotics from water bodies with an environmentally friendly strategy.Web of Science1839art. no. 220260

Calcium carbonate polymorph dictates in vitro osteoblast proliferation

Calcium carbonate (CaCO3) is a widely used material in biomedical applications owing to its biocompatibility and widespread occurrence in nature, especially in the exoskeletons of marine organisms. The ability to undergo polymorphic transformation between CaCO(3)polymorphs in aqueous environments provides a wide range of applications in the biomedical field, i.e. vaterite can gradually dissolve to release drugs or calcite can provide rigidity as a bone regeneration material. In this study, CaCO(3)particles including ellipsoidal vaterite, bowknot-like aragonite, and rhombohedral calcite were synthesized via solution mixing method by altering precursor ratio, pH, temperature, and solvent concentration. Afterwards, CaCO(3)particles were interacted with human bone cells (hFOB) to assess cellular proliferation for orthopedic applications. Results showed that hFOB cell viability can be altered by the polymorph and concentration of CaCO(3)particles. As an important finding, while proliferation of hFOB cells was promoted up to 5 days in vitro upon the interaction with vaterite and calcite particles, cellular proliferation was inhibited by aragonite particles at the highest particle concentration. Therefore, this work systematically showed the potential use of different CaCO(3)polymorphs in orthopedic applications

Synthesis of calcium carbonate microspheres via inert gas bubbling for orthopedic applications

Calcium carbonate (CaCO3) microspheres consisting of vaterite polymorph have been widely used in biomedical applications. Specifically, vaterite microspheres having hollow cores showed significant potential in drug delivery, however the spontaneous transformation of vaterite to other polymorphs in aqueous environments reduced its controlled in vivo release capability. In this work, calcite and aragonite microspheres having hollow/porous inner cores were synthesized -for the first time-using sodium dodecyl sulfate (SDS) stabilized nitrogen (N-2) bubbles as CaCO3 template in ethylene glycol (EG) solution and water as the precipitation medium. Results demonstrated that porous aragonite microspheres could be synthesized via N-2 gas incorporation, yet for the synthesis of hollow calcite microspheres, N-2 bubbles had be stabilized with SDS to be utilized as CaCO3 templates. The synthesized aragonite and calcite microspheres were found to be stable up to 5 days in Dulbecco's Modified Eagle's Medium (DMEM), and thus would not allow polymorphic transformation in aqueous environments, while promoting proliferation of human bone cells (hFOB) up to 5 days of culture. These findings -for the first time-identified a viable synthesis route for hollow/porous calcite and aragonite microspheres and indicated their promising use in orthopedic applications

Reconfigurable self-assembly of photocatalytic magnetic microrobots for water purification

Abstract The development of artificial small-scale robotic swarms with nature-mimicking collective behaviors represents the frontier of research in robotics. While microrobot swarming under magnetic manipulation has been extensively explored, light-induced self-organization of micro- and nanorobots is still challenging. This study demonstrates the interaction-controlled, reconfigurable, reversible, and active self-assembly of TiO2/α-Fe2O3 microrobots, consisting of peanut-shaped α-Fe2O3 (hematite) microparticles synthesized by a hydrothermal method and covered with a thin layer of TiO2 by atomic layer deposition (ALD). Due to their photocatalytic and ferromagnetic properties, microrobots autonomously move in water under light irradiation, while a magnetic field precisely controls their direction. In the presence of H2O2 fuel, concentration gradients around the illuminated microrobots result in mutual attraction by phoretic interactions, inducing their spontaneous organization into self-propelled clusters. In the dark, clusters reversibly reconfigure into microchains where microrobots are aligned due to magnetic dipole-dipole interactions. Microrobots’ active motion and photocatalytic properties were investigated for water remediation from pesticides, obtaining the rapid degradation of the extensively used, persistent, and hazardous herbicide 2,4-Dichlorophenoxyacetic acid (2,4D). This study potentially impacts the realization of future intelligent adaptive metamachines and the application of light-powered self-propelled micro- and nanomotors toward the degradation of persistent organic pollutants (POPs) or micro- and nanoplastics

Radiopaque nanorobots as magnetically navigable contrast agents for localized in vivo imaging of the gastrointestinal tract

Magnetic nanorobots offer wireless navigation capability in hard-to-reach areas of the human body for targeted therapy and diagnosis. Though in vivo imaging is required for guidance of the magnetic nanorobots toward the target areas, most of the imaging techniques are inadequate to reveal the potential locomotion routes. This work proposes the use of radiopaque magnetic nanorobots along with microcomputed tomography (microCT) for localized in vivo imaging applications. The nanorobots consist of a contrast agent, barium sulfate (BaSO4), magnetized by the decoration of magnetite (Fe3O4) particles. The magnetic features lead to actuation under rotating magnetic fields and enable precise navigation in a microfluidic channel used to simulate confined spaces of the body. In this channel, the intrinsic radiopacity of the nanorobots also provides the possibility to reveal the internal structures by X-ray contrast. Furthermore, in vitro analysis indicates nontoxicity of the nanorobots. In vivo experiments demonstrate localization of the nanorobots in a specific part of the gastrointestinal (GI) tract upon the influence of the magnetic field, indicating the efficient control even in the presence of natural peristaltic movements. The nanorobots reported here highlight that smart nanorobotic contrast agents can improve the current imaging-based diagnosis techniques by providing untethered controllability in vivo.Web of Scienc

Community acquired infections in elderly population

In geriatric practice, data regarding infections including the epidemiology, morbidity, and mortality are lacking. Our aim was to evaluate the frequency, location, microbiological and laboratory characteristics of infectious diseases in elderly population admitted to a training hospital. The patients were included total of 330 patients, aged over 65 with infection, seen between January 1, 2005 and January 1, 2006. In the result, of patients 136 (41%) had respiratory system infection, 90 (27%) urinary system infection, 39 (12%) gastrointestinal system infection, 34 (10%) bloodstream infections, 17 (5%) soft tissue infection, 8 (2%) central nervous system infections, and 6 (2%) others. Average length of hospitalization was 8.6 +/- 7.7 days. Mortality rate from all causes was 57 (17%). The most common infections in elderly patients were respiratory tract and urinary system infections, and there were no fever, leukocytes and high CRP levels in approximately 1/3 of cases. Infectious diseases may occur even in the absence of such infection indicators as fever, raised WBC count and high CRP level in the elderly population