Calcium Carbonate Microparticles Research Articles

Size-dependent therapeutic efficiency of 223Ra-labeled calcium carbonate carriers for internal radionuclide therapy of breast cancer.

The size of drug carriers strongly affects their biodistribution, tissue penetration, and cellular uptake in vivo. As a result, when such carriers are loaded with therapeutic compounds, their size can influence the treatment outcomes. For internal α-radionuclide therapy, the carrier size is particularly important, because short-range α-emitters should be delivered to tumor volumes at a high dose rate without any side effects, i.e. off-target irradiation and toxicity. In this work, we aim to evaluate and compare the therapeutic efficiency of calcium carbonate (CaCO3) microparticles (MPs, >2 μm) and nanoparticles (NPs, <100 nm) labeled with radium-223 (223Ra) for internal α-radionuclide therapy against 4T1 breast cancer. To do this, we comprehensively study the internalization and penetration efficiency of these MPs and NPs, using 2D and 3D cell cultures. For further therapeutic tests, we develop and modify a chelator-free method for radiolabeling of CaCO3 MPs and NPs with 223Ra, improving their radiolabeling efficiency (>97%) and radiochemical stability (>97%). After intratumoral injection of 223Ra-labeled MPs and NPs, we demonstrate their different therapeutic efficiencies against a 4T1 tumor. In particular, 223Ra-labeled NPs show a tumor inhibition of approximately 85%, which is higher compared to 60% for 223Ra-labeled MPs. As a result, we can conclude that 223Ra-labeled NPs have a more suitable biodistribution within 4T1 tumors compared to 223Ra-labeled MPs. Thus, our study reveals that 223Ra-labeled CaCO3 NPs are highly promising for internal α-radionuclide therapy.

Encapsulation of a small-molecule drug based on substituted 2-aminothiophenes in calcium carbonate carriers for therapy of melanoma.

Although small molecule drugs are widely used in chemotherapy, their low bioavailability, low-concentrated dose in the tumor zone, systemic toxicity, and chemoresistance can significantly limit the therapeutic outcome. These drawbacks can be overcome by two main strategies: (i) development of novel therapeutic molecules with more significant antitumor activity than currently available drugs and (ii) loading chemotherapeutic agents into drug delivery systems. In this study, we aimed to encapsulate a highly prospective small molecule drug based on substituted 2-aminothiophene (2-AT) into calcium carbonate (CaCO3) microparticles (MPs) for the treatment of melanoma tumors. In particular, we have optimized the encapsulation of 2-AT into MPs (2-AT@MPs), studied drug release efficiency, investigated cellular uptake, and evaluated in vivo biodistribution and tumor inhibition efficiency. In vitro results revealed that 2-AT@MPs were able to penetrate into tumor spheroids, leading to prolonged release of 2-AT. By performing intratumoral injection of 2-AT@MPs we observed significant melanoma suppressions in murine models: ∼0.084 cm3 for 2-AT@MPs at a dose of 0.4 g kg-1versus ∼1.370 cm3 for untreated mice. In addition, the 2-AT@MPs showed negligible in vivo toxicity towards major organs such as heart, lung, liver, kidney, and spleen. Thus, this work provided an efficient strategy for the improved chemotherapy of solid tumors by using an encapsulated form of small molecule drugs.

Adsorption of sodium alginate on calcium carbonate microparticles: Effect of molar mass and composition

Sodium alginate and calcium carbonate are natural materials with a high compositional variability. The molar mass and structural composition of sodium alginate and the crystalline structure of calcium carbonate can affect their interactions in pure water. Herein, we studied the adsorption of sodium alginate onto calcium carbonate microparticles in pure water. The adsorption appears to be driven by electrostatic interactions stabilized by calcium ions at the surface of the particles and in solution due to the dissolution of calcium carbonate in pure water. We found that the adsorption of sodium alginate is favored onto microparticles with more calcite. We also found that the adsorption of sodium alginate polymers with low guluronate content (~ 30%) onto calcium carbonate particles tends to increase for polymers with lower average molar mass and more flexible polymer chains. In contrast, polymers with high guluronate content (~ 65%) tend to adsorb more onto calcite when they present a lower average molar mass polymers as well as a higher proportion of guluronate monomers.

Characterization and Exploration of Placket-Burman-Designed Porous Calcium Carbonate (Vaterite) Microparticles.

The objective of the research was to identify significant variables that impact the porosity-related properties of CaCO3 particles. The Placket-Burman design was employed to screen multiple variables, including pH, molar concentrations of calcium chloride and sodium carbonate, temperature, concentration of Gelucire 44/14, Cremophor RH40, Solutol HS15, Labrasol, mixing rate, reaction time, and order of addition. The response variables were surface area, pore radius, and pore volume. Influential methodologies such as XRD, FTIR, Raman spectroscopy, and TGA were utilized to validate the precipitate type. The BET surface area ranged from 1.5 to 16.14 m2/g, while the pore radius varied from 2.62 to 6.68 nm, and the pore volume exhibited a range of 2.43 to 37.97 cc/gm. Vaterite structures with spherical mesoporous characteristics were observed at high pH, whereas calcite formations occurred at low pH. The order of addition impacted the surface area but did not affect the pore volume. To maximize the surface area, a lower reaction time and molar concentrations of sodium carbonate were found to be advantageous. The pore radius was influenced by the pH, surfactants, and reaction conditions. The sediments were categorized based on the percentage of vaterite formation. The instrumental techniques effectively characterized the precipitates and provided a valuable complementary analysis.

Superhydrophobic fluorescent micro-/nano-composites from carbon dots encapsulated in CaCO3-SiO2

ABSTRACT In this paper, polyamine-functionalized carbon dots (CDs) were synthesized by means of low temperature (<100°C) carbonization of citric acid at the presence of polyethylenimine (PEI), resulting spherical calcium carbonate micro-particles from inverse micro-emulsion system. Nanoscaled spherical silicas were prepared by Stöber method via deposition on the surface of micron calcium carbonate. Scanning- and transmission-electron microscopic analysis confirmed a micro-/nano-complex structure, enabling the composite material coating possessed coarser surface similar to those of ‘lotus leaf’. After modification with 1 H, 1 H, 2 H, 2 H-perfluorodecanethiol, both good super hydrophobicity and good fluorescent performance were confirmed by the water contact angle of 154.1°±1.5°, their surface-free energy, and fluorescence quantum yield of 14.1%, which provides an inexpensive and easy way to fabricate superhydrophobic material with fluorescence characteristics and promotes high value application of inorganic materials.

Effects of pigment volume concentration on radiative cooling properties of acrylic-based paints with calcium carbonate and hollow silicon dioxide microparticles

ABSTRACT Radiative cooling paints offer a sustainable method for reducing energy demand in buildings. This work investigates the effects of particle volume concentration (PVC) of calcium carbonate (CaCO3) and hollow silicon dioxide (SiO2) microparticles in acrylic-based paints on cooling capability. Paint solar reflectance increases as the total PVC increases until a peak PVC is reached. The addition of CaCO3 improves solar reflectance due to an enhancement in near-infrared reflection but decreases thermal emission. The paint, with a total PVC of 0.45 and a CaCO3:SiO2 PVC ratio of 1:1, offers the right balance between solar reflection and thermal emissivity and achieves the best cooling performance. This work demonstrates that the CaCO3-SiO2 paint system allows tuning of the radiative cooling performance.

A General Biomineralization Strategy to Synthesize Autologous Cancer Vaccines with cGAS-STING Activating Capacity for Postsurgical Immunotherapy.

Autologous cancer vaccines constructed by nonproliferative whole tumor cells or tumor lysates together with appropriate adjuvants represent a promising strategy to suppress postsurgical tumor recurrence. Inspired by the potency of cytosolic double-stranded DNA (dsDNA) in initiating anticancer immunity by activating the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) pathway, we herein report the concise synthesis of a cGAS-STING agonist through dsDNA-templated biomineralization growth of calcium carbonate (CaCO3) microparticles. The yielded DNA@CaCO3 can activate the intracellular cGAS-STING pathway of dendritic cells (DCs) by promoting endosomal escape of dsDNA, triggering their maturation and activation as a potent immune stimulator. Upon intratumoral injection, DNA@CaCO3 can reverse the immunosuppressive tumor microenvironment by simultaneously provoking innate and adaptive antitumor immunity, thereby effectively suppressing the growth of murine CT26 and B16-F10 tumors in mice. Furthermore, via CaCO3-based biomineralization of complete tumor lysates, we constructed a personalized autologous cancer vaccine with intrinsic cGAS-STING activation capacity that could provoke tumor-specific immune responses to not only delay the growth of challenged tumors but also synergize with anti-PD-1 immunotherapy to suppress postsurgical tumor recurrence. This study highlights a CaCO3-based biomineralization method to prepare autologous cancer vaccines in a concise manner, which is promising for personalized immunotherapy and clinical translation.

Vaterite microparticle-loaded methylene blue for photodynamic activity in macrophages infected with Leishmania braziliensis.

Calcium carbonate (CaCO3) exhibits a variety of crystalline phases, including the anhydrous crystalline polymorphs calcite, aragonite, and vaterite. Developing porous calcium carbonate microparticles in the vaterite phase for the encapsulation of methylene blue (MB) as a photosensitizer (PS) for use in photodynamic therapy (PDT) was the goal of this investigation. Using an adsorption approach, the PS was integrated into the CaCO3 microparticles. The vaterite microparticles were characterized by scanning electron microscopy (SEM) and steady-state techniques. The trypan blue exclusion method was used to measure the biological activity of macrophages infected with Leishmania braziliensis in vitro. The vaterite microparticles produced are highly porous, non-aggregated, and uniform in size. After encapsulation, the MB-loaded microparticles kept their photophysical characteristics. The carriers that were captured allowed for dye localization inside the cells. The results obtained in this study indicated that the MB-loaded vaterite microparticles show promising photodynamic activity in macrophages infected with Leishmania braziliensis.

Effect of phage vB_EcoM_FJ1 on the reduction of ETEC O9:H9 infection in a neonatal pig cell line

Enterotoxigenic Escherichia coli (ETEC) colonizes the intestine of young pigs causing severe diarrhoea and consequently bringing high production costs. The rise of antibiotic selective pressure together with ongoing limitations on their use, demands new strategies to tackle this pathology. The pertinence of using bacteriophages as an alternative is being explored, and in this work, the efficacy of phage vB_EcoM_FJ1 (FJ1) in reducing the load of ETEC EC43-Ph (serotype O9:H9 expressing the enterotoxin STa and two adhesins F5 and F41) was assessed. Foreseeing the oral application on piglets, FJ1 was encapsulated on calcium carbonate and alginate microparticles, thus preventing phage release under adverse conditions of the simulated gastric fluid (pH 3.0) and allowing phage availability in simulated intestinal fluid (pH 6.5). A single dose of encapsulated FJ1, provided to IPEC-1 cultured cells (from intestinal epithelium of piglets) previously infected by EC43, provided bacterial reductions of about 99.9% after 6 h. Although bacteriophage-insensitive mutants (BIMs) have emerged from treatment, the consequent fitness costs associated with this new phenotype were demonstrated, comparatively to the originating strain. The higher competence of the pig complement system to decrease BIMs’ viability, the lower level of colonization of IPEC-1 cells observed with these mutants, and the increased survival rates and health index recorded in infected Galleria mellonella larvae supported this observation. Most of all, FJ1 established a proof-of-concept of the efficiency of phages to fight against ETEC in piglet intestinal cells.

First experience with 224Radium-labeled microparticles (Radspherin®) after CRS-HIPEC for peritoneal metastasis in colorectal cancer (a phase 1 study).

Peritoneal metastasis (PM) from colorectal cancer carries a dismal prognosis despite extensive cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC). With a median time to recurrence of 11-12 months, there is a need for novel therapies. Radspherin® consists of the α-emitting radionuclide radium-224 (224Ra), which has a half-life of 3.6 days and is adsorbed to a suspension of biodegradable calcium carbonate microparticles that are designed to give short-range radiation to the serosal peritoneal surface linings, killing free-floating and/or tumor cell clusters that remain after CRS-HIPEC. A first-in-human phase 1 study (EudraCT 2018-002803-33) was conducted at two specialized CRS-HIPEC centers. Radspherin® was administered intraperitoneally 2 days after CRS-HIPEC. Dose escalation at increasing activity dose levels of 1-2-4-7-MBq, a split-dose repeated injection, and expansion cohorts were used to evaluate the safety and tolerability of Radspherin®. The aim was to explore the recommended dose and biodistribution using gamma-camera imaging. The results from the planned safety interim analysis after the completion of the dose-limiting toxicity (DLT) period of 30 days are presented. Twenty-three patients were enrolled: 14 in the dose escalation cohort, three in the repeated cohort, and six in the expansion cohort. Of the 23 enrolled patients, seven were men and 16 were women with a median age of 64 years (28-78). Twelve patients had synchronous PM stage IV and 11 patients had metachronous PM [primary stage II; (6) and stage III; (5)], with a disease-free interval of 15 months (3-30). The peritoneal cancer index was median 7 (3-19), operation time was 395 min (194-515), and hospital stay was 12 days (7-37). A total of 68 grade 2 adverse events were reported for 17 patients during the first 30 days; most were considered related to CRS and/or HIPEC. Only six of the TEAEs were evaluated as related to Radspherin®. One TEAE, anastomotic leakage, was reported as grade 3. Accordion ≥3 grade events occurred in a total of four of the 23 patients: reoperation due to anastomotic leaks (two) and drained abscesses (two). No DLT was documented at the 7 MBq dose level that was then defined as the recommended dose. The biodistribution of Radspherin® showed a relatively even peritoneal distribution. All dose levels of Radspherin® were well tolerated, and DLT was not reached. No deaths occurred, and no serious adverse events were considered related to Radspherin®.Clinical Trial Registration: Clinicaltrials.gov, NCT03732781.

Using phenolic polymers to control the size and morphology of calcium carbonate microparticles.

Calcium carbonate (CaCO3) is a naturally occurring mineral that occurs in biology and is used industrially. Due to its benign nature, CaCO3 microparticles have found use in the food and medical fields, where the specific size of the microparticles determine their functionality and potential applications. We demonstrate that phenolic polymers with different numbers of hydroxy groups can be used to control the diameter of CaCO3 microparticles in a range of 2-9 μm, and obtained particles were relatively uniform. The largest particles (∼9 μm in diameter) were obtained using poly(2,3,4,5-tetrahydroxystyrene) (P4HS), which showed the highest water solubility among the tested phenolic polymers. The polymer concentration and stirring speed influenced the size of microparticles, where the size of the obtained particles became smaller as the concentrations of phenolic polymers increased and as the stirring speed increased, both likely due to promoting the formation of a large number of individual crystal seeds by shielding seed-seed fusion and increasing the chances for precursor contact, respectively. The preparation time and temperature had a great influence on the morphology of the CaCO3 particles, where vaterite transforms into calcite over time. Specifically, aragonite crystals were observed at preparation temperature of 80 °C and vaterite particles with rough surfaces were obtained at 40 °C. Molecular weight and scale of reaction were also factors which affect the size and morphologies of CaCO3 particles. This research represents a facile method for producing relatively monodisperse CaCO3 microparticles with diameters that have previously proven difficult to access.

Modulation of double-network hydrogels via seeding calcium carbonate microparticles for the engineering of ultrasensitive wearable sensors

Stretchable and tough double-network hydrogels mediated by CaCO3 microparticles can be used to monitor human motions and mild pain signals at the wound site.

Complex destruction of textured water-repellent coatings under the influence of UV and water flow

The resistance of micro- and nanotextured coatings to aggressive factors of ultraviolet radiation, immersion in water and water flow has been studied. These coatings were obtained using calcium carbonate microparticles modified with stearic acid and colloidal silica nanoparticles treated with dimethyldichlorosilane. The inherent aging rate of polymeric materials under UV radiation is compared with the treated surface layer of hydrophobized particles. The influence of immersion in water and friction of the water flow on the Cassie state stability have been established. А mechanism for the destruction of organo-mineral coatings based on the balance of the rates of UV degradation, detachment of particles in water, degradation of the polymer and the treated surface layer of particles is proposed.

Intraperitoneal alpha therapy with 224Ra-labeled microparticles combined with chemotherapy in an ovarian cancer mouse model.

A novel alpha-therapy consisting of 224Ra-labeled calcium carbonate microparticles (224Ra-CaCO3-MP) has been designed to treat micrometastatic peritoneal disease via intraperitoneal (IP) administration. This preclinical study aimed to evaluate its efficacy and tolerability when given as a single treatment or in combination with standard of care chemotherapy regimens, in a syngeneic model of ovarian cancer in immune competent mice. Female C57BL/6 mice bearing ID8-fLuc ovarian cancer were treated with 224Ra-CaCO3-MP 1 day after IP tumor cell inoculation. The activity dosages of 224Ra ranged from 14 to 39 kBq/mouse. Additionally, 224Ra-CaCO3-MP treatment was followed by either carboplatin (80 mg/kg)-pegylated liposomal doxorubicin (PLD, 1.6 mg/kg) or carboplatin (60 mg/kg)-paclitaxel (10 mg/kg) on day 14 post tumor cell inoculation. All treatments were administered via IP injections. Readouts included survival, clinical signs, and body weight development over time. There was a slight therapeutic benefit after single treatment with 224Ra-CaCO3-MP compared to the vehicle control, with median survival ratios (MSRs) ranging between 1.1 and 1.3. The sequential administration of 224Ra-CaCO3-MP with either carboplatin-paclitaxel or carboplatin-PLD indicated a synergistic effect on overall survival at certain 224Ra activities. Moreover, the combinations tested appeared well tolerated in terms of weight assessment in the first 4 weeks after treatment. Overall, this research supports the further evaluation of 224Ra-CaCO3-MP in patients with ovarian cancer. However, the most optimal chemotherapy regimen to combine with 224Ra-CaCO3-MP should be identified to fully exploit its therapeutic potential.

Filtration of Paint‐Contaminated Water by Electrospun Membranes

AbstractMicro‐ and nanosized plastics as persistent anthropogenic pollutants have attracted more and more attention in recent years. A source of nanoparticles is, for example, water‐borne dispersion paint, which consists of a variety of different materials with potential adverse effects on living systems. Therefore, a rising challenge becomes apparent to investigate remediation strategies for environmental media. This problem is addressed by utilizing electrospun membranes for filtration applications because of their outstanding properties, such as their high surface‐to‐volume ratio and ease of functionalization. The electrospun membranes are able to successfully filter different paint components, such as titanium dioxide and polyacrylate nanoparticles, as well as dispersed polymers and calcium carbonate microparticles. Besides the known size‐exclusion mechanism, the membranes featured extraordinary properties, such as effective separation of components smaller than the pore size of the electrospun membranes. This property occurs due to the fiber surface functionalization and enables not only filtration of nanosized or dissolved mater at high filtration efficiencies up to 100% but also at a very low operating pressure. This combination of filter material properties cannot be achieved by conventional nanofiltration membranes and thus, demonstrates the high potential of electrospun membranes for the application in filtration for future environmental pollutants.

First experience with 224Radium-labelled microparticles (radspherin) after CRS-HIPEC for peritoneal metastasis in colorectal cancer (a phase 1 study).

3599 Background: Peritoneal metastasis (PM) from colorectal cancer carries a dismal prognosis. Improved survival can be achieved by combining extensive cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC). However, median time to recurrence is short (11-12 months) and there is a need for novel therapies to prevent subsequent PM. Radspherin consists of the α-emitting radionuclide radium-224 (224Ra), half-life 3.6 days, adsorbed to a suspension of biodegradable calcium carbonate microparticles, designed to give short-range radiation to the serosal peritoneal surface, aiming to kill remaining free cancer cells and small tumor cell clusters. Methods: A first-in-man phase 1 study (EudraCT 2018-002803-33) was conducted at two specialized CRS-HIPEC centers. Radspherin was injected in the abdominal cavity through a catheter 2 days after CRS-HIPEC. Dose escalation at increasing dose levels of 1-2-4-7-MBq, repeated injection and expansion cohorts evaluated the safety and tolerability of Radspherin, explored maximal tolerated dose and biodistribution by using single photon-emission computed tomography/computed tomography (SPECT/CT) imaging. Results from the planned safety interim analysis after completion of the dose-limiting toxicity (DLT) period are presented. Results: Twenty-three patients were enrolled, dose escalation cohort (14), repeated cohort (3) and expansion cohort (6). Nineteen patients were treated in Oslo/ 4 in Uppsala. Twelve patients had synchronous PM Stage IV and 11 metachronous PM (Stage II (6), Stage III (5). Disease-free interval 15 months (3-39); males (7), females (16); median age 64 years (28-78). Peritoneal cancer index was median 7 (3-19), operation time 395 minutes (194-515) and hospital stay 12 days (7-37). Accordion ≥3 grade events (6); including anastomotic leaks (2); abscess (1); drains (2) and missed lesion (1), all reported as serious adverse events (SAEs). The 7MBq dose was selected as recommended dose as no DLT was observed. A total of 185 treatment emergent adverse effects (TEAE) were recorded, most were of low grade and considered related to CRS and/or HIPEC. Few patients (7) had TEAEs considered related to a combined impact of Radspherin and CRS-HIPEC. The biodistribution of Radspherin showed a relatively even peritoneal distribution, and no patients had compartments of the abdominal cavity without radioactivity (cold spots), and low number had hot spots. Long-term safety, dosimetry and first efficacy results of Radspherin will be reported after 12 months follow up period. Conclusions: All dose levels of Radspherin were well tolerated with DLT not reached. No deaths occurred and no SAEs were considered related to Radspherin. The biodistribution of Radspherin showed good peritoneal distribution of the radiolabeled microparticles. Clinical trial information: 2018-002803-33.

Fabrication of Porous Phosphate/Carbonate Composites: Smart Fertilizer with Bimodal Controlled-Release Kinetics and Glyphosate Adsorption Ability.

A simple method to prepare phosphate/carbonate composites for use as porous sponge-like phosphate fertilizers (ps-PO4Fs) is presented. The composites ps-PO4Fs were prepared by ion-exchange implantation of phosphate onto the surface of vaterite-phase calcium carbonate (CaCO3) microparticles. The ps-PO4Fs obtained under the optimized conditions were found to contain a nanoscale porous network of calcium phosphate covering the CaCO3 support. In addition, ps-PO4Fs exhibited two distinct phosphate release modes having different kinetics: a fast-release step over the initial 24 h period following a parabolic diffusion model, indicating controlled diffusion from external surfaces/edges, and a second slow-release step over the course of a month following the Ritger–Peppas model, indicating the release and diffusion of phosphate adsorbed at specific sites. The ps-PO4Fs also adsorbed glyphosate well because of their porous structure and large surface area. However, glyphosate adsorption prevented phosphate release at concentrations greater than 10 mg L–1. The ps-PO4Fs were tested for their effects on plant growth and showed effects similar to commercial fertilizers. In summary, these smart, eco-friendly, and multifunctional fertilizers having two-stage phosphate release could enable the application of lower amounts of fertilizer and remove excess glyphosate from the environment.

Effect of Particle Carriers for Intraperitoneal Drug Delivery on the Course of Ovarian Cancer and Its Immune Microenvironment in a Mouse Model.

Novel treatment strategies are needed to provide a better prognosis for ovarian cancer. For this purpose, the current study was designed to evaluate the effects of different types of particle drug carriers on tumor response and on the tumor immune microenvironment (TME) after intraperitoneal (IP) administration in a murine tumor model. Mice with ID8-fLuc ovarian cancer were injected IP with pegylated liposomes, hydroxyapatite, polystyrene, poly(lactic-co-glycolic acid) (PLGA) and calcium carbonate (CaCO3) microparticles to evaluate the effect of the candidate carriers without drugs. Our results show that several types of microparticle drug carriers caused hyperproliferation of the tumor when injected IP, as reflected in a reduced survival or an accelerated onset of ascites. Alterations of the product formulation of CaCO3 microparticles could result in less hyperproliferation. The hyperproliferation caused by CaCO3 and PLGA was largely driven by a strong innate immune suppression. A combination with chemotherapy was not able to sufficiently counteract the tumor progression caused by the drug carriers. This research points towards the importance of evaluating a drug carrier before using it in a therapeutic setting, since drug carriers themselves can detrimentally influence tumor progression and immune status of the TME. However, it remains to be determined whether the hyperproliferation in this model will be of relevance in other cancer models or in humans.

Multilayer dextran derivative based capsules fighting bacteria resistant to Antibiotic: Case of Kanamycin-Resistant Escherichia coli

Bacteria resistance to antibiotics has emerged as a major health problem. Developing new antibacterial systems is then of major interest. In this sense, we present biocapsules presenting inherent antibacterial capacity. The self-assembly of charged biopolymer, namely diethylaminoethyl-dextran hydrochloride (dex+) and dextran sulfate (dex-), were done on calcium carbonate microparticles, used as a template. Zeta potential measurements have shown the successful alternate adsorption of these biopolymers and related charge reversal upon the multilayer film construction onto the particles surface. The shape of the capsules was characterized by scanning electron microscopy (SEM). These particles were tested against bacteria resistant to antibiotics, namely kanamycin-resistant Escherichia coli. An inhibitory effect of the particles was observed during bacterial growth in liquid medium, i.e. in the range of 10 % for (dex+/dex-)n coated CaCO3 materials and of 50% for (dex+/dex-)n capsules. These findings evidence the high potential of capsules to act as antimicrobial agents in future and in treatments against infections.

Coherent X-ray diffraction imaging to investigate structure and morphological evolution of calcium carbonate microparticles

Coherent X-ray diffraction imaging to investigate structure and morphological evolution of calcium carbonate microparticles