Dagnija Loca

Dagnija Loca
Riga Technical University | RTU · Riga Biomaterials Innovation and Development Centre of Riga Technical University

Dr.sc.ing.

About

65
Publications
11,491
Reads
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950
Citations
Education
September 2000 - May 2009
Riga Technical University
Field of study
  • Materials Sciences

Publications

Publications (65)
Article
Full-text available
Out of the wide range of calcium phosphate (CaP) biomaterials, calcium phosphate bone cements (CPCs) have attracted increased attention since their discovery in the 1980s due to their valuable properties such as bioactivity, osteoconductivity, injectability, hardening ability through a low-temperature setting reaction and moldability. Thereafter nu...
Poster
Full-text available
This poster was presented at the Scandinavian Society for Biomaterials (ScSB) 15th Annual Meeting from 13th to 15th June 2022.
Article
Full-text available
The design of multifunctional hydrogels based on bioactive hyaluronic acid (HA) and antibacterial cationic polymer ɛ-poly-l-lysine (ε-PL) is a promising tool in tissue engineering applications. In the current study, we have designed hyaluronic acid and ɛ-polylysine composite hydrogel systems with antibacterial and cell attractive properties. Two di...
Article
Full-text available
The genotoxic effect was assessed using the cytokinesis-block micronucleus assay with fluorescent staining. Results showed that a 0.66-T static MF exposure had no significant long-term effect on cell viability and chromosomal damage but demonstrated a short-term effect on cell apoptosis. Significant increase in nuclear bud formation was observed. T...
Article
Full-text available
In the present manuscript, a brief overview on barium, its possible utilization, and the aftermath of its behavior in organisms has been presented. As a bivalent cation, barium has the potential to be used in a myriad of biochemical reactions. A number of studies have exhibited both the unwanted outcome barium displayed and the advantages of barium...
Article
Full-text available
Disadvantages of conventional drug delivery systems (DDS), such as systemic circulation, interaction with physiochemical factors, reduced bioavailability, and insufficient drug concentration at bone defect site, have underlined the importance of developing efficacious local drug delivery systems. Octacalcium phosphate (OCP) is presumed to be the pr...
Article
Recently premixed calcium phosphate cement pastes have been proposed as biomaterials for bone tissue repair and regeneration. Use of premixed pastes saves the time and removes an extra step during a medical operation. α-Tricalcium phosphate (α-TCP) based cements set to form calcium deficient hydroxyapatite which has a moderate bioresorbtion speed....
Article
In this study we determined sintering temperature effect on bovine serum albumin (BSA) adsorption and compressive strength of calcium phosphate ceramic granules. Hydroxyapatite (HAp) and biphasic calcium phosphate (BCP) with HAp and β-tricalcium phosphate ratio 50:50 granules were prepared by sintering at 1000, 1100, 1150 and 1200 °C. HAp granules...
Article
Full-text available
Site specific drug delivery systems (DDS) are usually developed to overcome the side effects of conventional ones (e.g. injections or oral ingestions), creating smart drug delivery vehicles characterized with greater efficiency, safety, predictable therapeutic response as well as controlled and prolonged drug release periods. DDS made of hyaluronic...
Poster
Full-text available
Chinese hamster ovary (CHO) cells are widely used for biopharmaceutical production. Production of recombinant cytokines, fusion proteins, monoclonal antibodies and others requires specific nutrient components to support cell growth in vitro [1]. The main energy sources in a chemically defined CHO cell culture media are carbohydrates (primarily, glu...
Article
Computational Fluid Dynamics (CFD) is the analysis of fluid behaviour employing numerical solution methods. Using CFD it is possible to analyse simple and complex fluid-gas, fluid-fluid or fluid-solid interactions. Fluid dynamics is described with laws of physics in the form of partial differential equations also known as Navier-Stokes equations. S...
Article
Full-text available
Advantageous cultivation procedures for the Chinese hamster ovary (CHO) cells are necessary for the productive commercial production of biopharmaceuticals. A main challenge that needs to be addressed during the process development is the differences in each cell line requirements concerning the nutrients and feed strategies in order to achieve the...
Poster
Full-text available
The research on the influence of magnetic field on mammalian cells associated with the development of electronic technologies has been going on for several decades. Nowadays, the growing interest in this field can be associated with the development of vessels with magnetic stirrers as mixing systems in both drug substance and drug product manufactu...
Article
Full-text available
It has been recognized that the operative stabilization of osteoporotic fractures should be followed up with an appropriate osteoporosis treatment in order to decrease the risk of repeated fractures. Despite the good clinical results of strontium ranelate (SrRan) towards the osteoporosis treatment, high drug doses and long treatment period cause an...
Article
Composite hydrogels on the basis of hydroxyapatite (HAp) and polyvinyl alcohol (PVA) has been proposed as a promising materials for bone and cartilage tissue engineering. HAp/PVA composite hydrogels with phase ratio 50:50wt% and 70:30wt% were obtained via in situ wet chemical precipitation technique in combination with the freeze-thawing approach....
Article
α-Tricalcium phosphate (α-TCP) is an important reactive component in calcium phosphate bone cements which are used for the bone tissue regeneration and augmentation. By thermally treating amorphous calcium phosphate (ACP) at relatively low temperatures (650–900 °C), it is possible to obtain sub-micrometre or nanosized α-TCP particles. In the curren...
Article
Full-text available
Recent progress made in biomaterials and their clinical applications is well known. In the last five decades, great advances have been made in the field of biomaterials, including ceramics, glasses, polymers, composites, glass-ceramics and metal alloys. A variety of bioimplants are currently used in either one of the aforesaid forms. Some of these...
Article
Composite biomaterials are of great interest in tissue engineering and regenerative medicine. Composites partially exhibit the properties of their starting materials but, through rational design, they can be endowed with synergistic effects, overcoming the limitations of the single components. Calcium phosphate/polyvinyl alcohol (CaP/PVA) composite...
Article
The review covers historical and last decade's scientific literature on the biological and clinical role of strontium (Sr) and strontium ranelate (Sr RAN). It enrols the description of the main effects of Sr on supportive tissue, its proven and possible morphopathogenetical mechanisms and the interaction with the bone, and especially focuses on the...
Article
Bacterial infections are a major problem in bone tissue regeneration, thus it is essential to incorporate antibacterial properties within the bone scaffolds. Silver compounds are frequently used as antibacterial agents to prevent bacterial infections and numerous studies have shown that silver ions can be incorporated within the biocompatible and o...
Article
It is well known that polyvinyl alcohol hydrogel-based (PVA-H) biomaterials are promising materials for damaged articular cartilage replacement, but their application for bone tissue engineering is restricted due to insufficient mechanical properties. Thus, to meet the demands of the bone substitute material, PVA-H are reinforced with hydroxyapatit...
Article
One of the most used calcium phosphate implant materials in bone tissue regeneration is synthetic hydroxyapatite, which is similar to mineral phase of bone. By adding antibacterial effect to hydroxyapatite properties and creating controlled drug delivery systems based on this material, it is possible to obtain multifunctional material. Thus, in thi...
Article
Osteoporosis is a disease characterized with reduced density and quality of bone. Novel treatment strategies have been developed with the aim to inhibit excessive bone resorption and to increase bone formation. Strontium ranelate (SrRan), a novel orally active agent consisting of two atoms of stable strontium and the organic moiety ranelic acid, ha...
Article
α-Tricalcium phosphate is an important ingredient of calcium phosphate bone cements, which are used for bone defect augmentation and repair. In this study sub-micrometre sized α­tricalcium phosphate particles were synthesized by heat treating amorphous calcium phosphate. Size of synthesized particles depended on duration and temperature of heat tre...
Article
The combination of calcium phosphate compounds and hyaluronan is expected to have advantages of both materials to be used as optimal scaffold for bone tissue engineering. It possesses the fundamental necessary characteristics such as bioactivity, biomechanical similarity, processability, and biodegradability. Preparation technology and properties o...
Article
Calcium phosphate ceramics are one of the most studied biomaterials for bone substitution and regeneration. Bioactivity is one of the most important properties for these materials and it can be evaluated by adsorption of proteins and by hydroxyapatite formation on the surface in simulated body fluid (SBF). The aim of this work was to evaluate the b...
Article
In this work, nanocrystalline hydroxyapatite (HAp) powders were synthesized through wet precipitation method by adjusting the reaction temperature between 0 °C and 5 °C. The influence of biologically active Mg and Sr addition on HAp crystalline structure and thermal behavior was assessed. In all synthesis, nanocrystalline and/or amorphous HAp was f...
Article
Full-text available
The aim of this work was to evaluate the effect of precursor materials used in the synthesis on the Sr incorporation levels into the hydroxyapatite (HAp) lattice and to characterize the synthesis products. HAp powders containing various amounts of Sr were synthesized through three different precipitation routes. In all cases, the as-synthesized pro...
Article
The disadvantages of systemic drug therapy are that only a small fraction of any given dose actually reaches the surgical site, producing low-therapeutic tissue levels. An alternative approach is based on the use of implantable delivery tools, able to release the active substance in a controlled way. Biocompatibility, bioactivity, and osteoconducti...
Article
Full-text available
In the last five decades, there have been vast advances in the field of biomaterials, including ceramics, glasses, glass-ceramics and metal alloys. Dense and porous ceramics have been widely used for various biomedical applications. Current applications of bioceramics include bone grafts, spinal fusion, bone repairs, bone fillers, maxillofacial rec...
Article
A new family of 45S5 Bioglass®-based scaffolds with local drug delivery capability was developed and characterized. The basic scaffold fabricated by the foam replica technique was impregnated with zoledronic acid and coated with poly(L-lactic acid) resulting in scaffolds with improved compressive strength in comparison with non-coated scaffolds and...
Article
Among calcium phosphate biomaterials, calcium phosphate bone cements (CPCs) have attracted increased attention because of their ability of self-setting in vivo and injectability, opening the new opportunities for minimally invasive surgical procedures. However, any surgical procedure carries potential inflammation and bone infection risks, which co...
Article
In the present study, the in vitro bioactivity of silver-doped hydroxyapatite (HAp/Ag) scaffolds was investigated. HAp/Ag was prepared using two different modified wet precipitation methods. The X-ray powder diffraction (XRD) results showed, that sintered HAp/Ag samples prepared using method (I) contain two phases HAp and Ag, but samples prepared b...
Article
Conventional calcium phosphate bone cements are self setting water based pastes. Recently pre-mixed calcium phosphate bone cements have been proposed that have non-aqueous fluid as liquid phase of the paste. Such cements thus only start setting reaction in contact with body fluids. In this work the properties (cohesion, compressive strength, phase...
Article
Full-text available
Calcium phosphate (CaP) bioceramic is well known as bioactive and biocompatible material in bone tissue regeneration applications. Apatitic CaP, especially nano sized hydroxyapatite (NHAp), is more similar to the natural apatite presented in the bone tissue than CaP bioceramics. In the current research NHAp was modified using biodegradable polymer...
Article
In the present study, the effect of the preparation method on the physical and antibacterial properties of silver doped hydroxyapatite (HAp/Ag) samples was investigated. HAp/Ag with 0.1-5 % of silver was prepared using two different modified wet chemical precipitation methods. A comparison of thermal stability and thermodynamical properties indicat...
Article
Abstract The extremely high hygroscopicity (solubility in water ≥2 g/ml) of the pharmaceutical preparation mildronate defines specific requirements to both packaging material and storage conditions. To overcome the above mentioned inconveniences, microencapsulated form of mildronate was developed using polystyrene (PS) and poly (lactic acid) (PLA)...
Article
In the present study, the impact of sintering temperature on the phase composition and antibacterial properties of silver-doped hydroxyapatite (HAp/Ag) samples was investigated. HAp/Ag containing 0.2 and 1.2 % silver was prepared using a modified wet chemical precipitation method. The surface morphology and inner structure of the sintered samples w...
Article
Calcium phosphate ceramic materials in form of hydroxylapatite (HAp) and β-tricalcium phosphate (TCP) are good candidates for bone substitution and regeneration. Majority of methods used for biphasic calcium phosphate (mixture of HAp and TCP) preparation includes synthesis of calcium deficient apatite, not so often mechanical mixing of HAp and TCP...
Article
Novel lidocaine containing calcium phosphate bone cements have been developed. Lidocaine release kinetics of these cements have been evaluated.Calcium phosphate cements have a great potential for local drug delivery. Release of local anesthetic, such as lidocaine, at the implant site can be useful for reducing pain immediately after implantation.In...
Article
Due to its bioactivity, hydroxyapatite (HAp) is one of the most perspective materials for controlled drug delivery. Biodegradable polymers like chitosan and sodium alginate are used as coating materials for ceramic scaffolds. In this work the application of HAp/sodium alginate or chitosan composite materials which provide controlled lidocaine relea...
Article
Aim: The aim of this study was to evaluate the osteorigenerative properties of AFSc associated with hydroxyapatite, and compare their behaviour with the use of biomaterial in sinus grafts on ovine model. Methods: Two SL were carried out with hydroxyapatite and AFSc in the test side, while in the control side only hydroxyapatite was inserted. Histol...
Article
I attacched Abstract. For more complete information contact please to corresponding author . N.Romanchikova Evaluation of bioceramic bone substitutes – hydroxyapatite (HAP), tricalcium phosphate (TCP) and biphasic ceramic (HAP/TCP) in vitro and in vivo I. Salma1, , G. Salms2, 3, M. Pilmane1, 4, D. Loca1, J. Locs1, N. Romanchikova1, A. Skagers1, 3...
Article
Full-text available
The conventional methods of supplying a patient with pharmacologic active substances suffer from being very poorly selective, so that damage can occurs to the healthy tissues and organs, different from the intended target. In addition, high drug doses can be required to achieve the desired effect. An alternative approach is based on the use of impl...
Article
In the current research slow release anticancer drug delivery system was prepared and drug release kinetics in vitro evaluated. Porous hydroxyapatite (HAp) as carrier material and doxorubicin hydrochloride (DOX) as anticancer agent was used. DOX is an anthracycline drug commonly used in cancer chemotherapy. Unfortunately, its therapeutic potential...
Article
Sorption experiments of bovine serum albumin (BSA) on hydroxyapatite (HAp) ceramic granules, prepared at three temperatures 900°C, 1000°C and 1150°C were performed at room temperature 18,6 °C and phosphate buffer, pH 5,83; 6.38 and 7,39. Thermal treatment contributed to the decrease of bovine serum albumin immobilization indicating that sorption pr...
Article
Full-text available
Proinflammatory cytokines mediate bone loss around the implants in patients with peri-implant disease. However, there is no complete data about the expression of cytokines into the bone around the implants. The aim of this work was to investigate the distribution and appearance of inflammatory cytokines and anti-inflammatory proteins in the bone of...
Article
Local drug delivery devices especially based on osteoconductive porous calcium phosphate ceramics are of clinical importance. However, the brittleness, pore structure, porosity and pore size should be controlled for their wider applications in hard tissue implants and load bearing compartments. An approach to the fabrication of the bone graft exhib...
Article
Pine (Pinus silvestris) wood samples were dried and impregnated with a SiO2 sol from a sol–gel process. The impregnation involved a two step process in a custom-made apparatus. Impregnated samples were dried and pyrolised at 500 °C under an oxygen-free atmosphere. SiC synthesis was performed in a high-temperature furnace in an argon atmosphere at a...
Article
Local drug delivery devices especially based on osteoconductive porous calcium phosphate ceramics are of clinical importance. However, the brittleness, pore structure, porosity and pore size should be controlled for their wider applications in hard tissue implants and load bearing compartments. An approach to the fabrication of the bone graft exhib...
Article
Synthetic calcium phosphates (CaP) are widely used as bone scaffolds due to their biocompatibility and osteoconductive properties. To be used as drug delivery systems, the pore structure of the scaffolds needs to be controlled in terms of porosity, pore size and pore interconnectivity. In this research hydroxyapatite/β-tricalcium phosphate biphasic...
Article
Pine (Pinus silvestris) wood with shaped sample dimensions of 20 mm × 20 mm × 5 mm (axial) was selected as the raw material. Samples were dried and, for a half of the samples, resin extraction from the sample was applied. SiO2 sol was prepared, and samples were impregnated under different vacuum/pressure conditions. Relative impregnation efficiency...
Article
In past years scientists have interest in new specific TiO2 properties, which result from oxygen and titanium ratio in ceramic. Recently such TiO2 applications as implantable biomaterials in medicine and photocatalysts in purification of waste water become very significant. High temperature vacuum treated titanium oxide ceramics become biologically...
Article
Pine tree (Pinus silvestris) with shaped sample dimensions of 20 x 20 x 5mm (axial) was selected as raw material. Samples were dried and, for half of samples, resin extraction from sample was applied. SiO2 sol was prepared using sol-gel technology. Ethanol, tetraetoxysilane, distilled water and hydrochloric acid was used as sol raw materials. Sampl...
Article
Microencapsulation of highly water soluble pharmaceutical substances (solubility more than 1g/ml), especially if high drug loading is required (more than 50%) is a big challenge. Biodegradable polylactide as coating material and polyvinyl alcohol as surfactant were found suitable for this purpose. Active substance was microencapsulated using slight...
Chapter
Microencapsulation of highly water soluble pharmaceuticals (solubility more than mg/ml) especially if high drug loading is required (more than 50%) is a big challenge. Biodegradable poly(lactic acid) (PLLA) as coating material and polyvinyl alcohol as surfactant were found suitable for this purpose. Active substance was microencapsulated using slig...
Article
The inhibition of gamma-butyrobetaine (GBB) hydroxylase, a key enzyme in the biosynthesis of carnitine, contributes to lay ground for the cardioprotective mechanism of action of mildronate. By inhibiting the biosynthesis of carnitine, mildronate is supposed to induce the accumulation of GBB, a substrate of GBB hydroxylase. This study describes the...

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Projects (3)
Project
In INJECT-BIO project, the development of advanced biomaterials and drug delivery systems for oral soft tissue regeneration will be investigated by applying Halomanas levan and bacterial cellulose-based injectable hydrogels containing IGF-1 and cannabis extract/cannabidiol liposomal simultaneous delivery systems.
Project
Is to develop a synthetic bone graft substitute with superior bone regenerative properties that are comparable to the "golden standard".
Project
The establishment of the Baltic Biomaterials Centre of Excellence (BBCE) under the frame of Horizon 2020 Teaming Phase 2 will provide an opportunity to combine the expertise and infrastructure of internationally recognized Research Teams from Latvia, Germany and Switzerland, ensuring the platform for excellence in the development of biomaterials for bone regeneration and new solutions for creative biomedical applications. The strategic direction of the BBCE is research and development of patient-specific personalized solutions for bone regeneration in 3 levels: biomaterial composition, geometry and bioactive compound delivery. The full cycle of bone regenerating biomaterial development consists of continuous steps, starting from the development of biodegradable, osteoconductive and osteoinductive materials, composites and drug delivery systems, then followed by preclinical in vitro/in vivo investigations, finally leading to the clinical trials. The overall objective of the BBCE is to develop a joint Centre of Excellence for advanced biomaterial development based on the long-term strategic cooperation between Riga Technical University (RTU), Latvian Institute of Organic Synthesis (LIOS), Riga Stradiņs University (RSU) and LLC Riga Stradiņs University Institute of Stomatology (RSU IS), on the one part, and AO Research Institute Davos, Switzerland (ARI) and Friedrich-Alexander University of Erlangen-Nuremberg, Germany (FAU), on the other part.