Uncovering the crystal defects within aragonite CaCO3.

Knowledge of deformation mechanisms in aragonite, one of the three crystalline polymorphs of CaCO3, is essential to understand the overall excellent mechanical performance of nacres. Dislocation slip and deformation twinning were claimed previously as plasticity carriers in aragonite, but crystallographic features of dislocations and twins have been poorly understood. Here, utilizing various transmission electron microscopy techniques, we reveal the atomic structures of twins, partial dislocations, and associated stacking faults. Combining a topological model and density functional theory calculations, we identify complete twin elements, characters of twinning disconnection, and the corresponding twin shear angle (∼8.8°) and rationalize unique partial dislocations as well. Additionally, we reveal an unreported potential energy dissipation mode within aragonite, namely, the formation of nanograins via the pile-up of partial dislocations. Based on the microstructural comparisons of biogenic and abiotic aragonite, we find that the crystallographic features of twins are the same. However, the twin density is much lower in abiotic aragonite due to the vastly different crystallization conditions, which in turn are likely due to the absence of organics, high temperature and pressure differences, the variation in inorganic impurities, or a combination thereof. Our findings enrich the knowledge of intrinsic crystal defects that accommodate plastic deformation in aragonite and provide insights into designing bioengineering materials with better strength and toughness.

Attitudes of oncology patients' towards biospecimen donation for biobank research.

BACKGROUND: Since the biological material that remains after diagnostic and therapeutic procedures plays crucial role in biobank research, this study aims to explore cancer patients' views on the donation of biospecimens for research purposes. METHODS: 548 oncology patients from two hospitals with oncology treatment units in Poznan, Poland, completed an anonymous, self-administered pen-and-paper questionnaire. RESULTS: Although only 43.4% of patients had heard of biobanks, 93.1% declared themselves willing to donate. 71.1% of patients believed that doctors should ask patients to donate, and 60.9% that this should be done before the medical procedure. While 65% of patients were willing to donate any type of tissue that remained after a medical procedure, blood, saliva and hair were indicated most frequently. 40.5% of patients would donate their entire body after death and 21% would refuse. Patients' support for biobanks was mainly driven by the desire to support science, help advance cancer research and altruism. Some respondents expected health information or medical treatment. The most common barriers for donation were physical distance, repeated examinations, concerns over the privacy and confidentiality of data and the commercial or unethical use of samples. Patients' attitudes toward biobank donation seemed to be associated with age, education level, declared religiousness, a family history of genetically determined diseases and whether they were a blood donor. CONCLUSIONS: Although cancer patients' lack of biobank awareness had no effect on their affirmative attitudes towards biobank research, there is a need to further increase patients' support and overcome possible barriers that might hinder their willingness to donate.

An overview of preconcentration techniques combined with inductively coupled plasma mass spectrometry for trace element determination in biological studies.

In the last decades, the determination of trace elements in biological materials has emerged as an important area of study because of its relevance to human health and the environment. Inductively coupled plasma mass spectrometry (ICP-MS) has proven to be a powerful tool for trace element analysis, owing to its high sensitivity and ability to determine several elements in a single measurement. However, given the complex nature of biological matrices and the presence of elements, most of them at ultratrace levels, it becomes crucial to complement ICP-MS with preconcentration techniques to increase the sensitivity and selectivity of analytical methods. This article presents an exhaustive overview of liquid- and solid-phase preconcentration techniques used in combination with ICP-MS for trace element determination in different biological samples from 2000 to the present. An in-depth discussion of the advances on the application of state-of-the-art solvents and materials in trace element extraction and preconcentration is presented. Special attention is given to different strategies for elemental speciation analysis, employing both chromatographic and non-chromatographic techniques. The role of automation in these methodologies is also described. Finally, future trends and challenges related to this topic are discussed.

When Biobanks Meet Religion: Association Between Religiosity and Attitudes of Polish Medical Students Toward Biobanking of Human Biological Material for Research Purposes.

While biobanking is expanding globally, the empirical evidence concerning the impact of religion on future healthcare professionals' awareness and willingness to donate biospecimens for biobank research is lacking. To understand how medical students' religious beliefs can fuel their questions regarding how biospecimens would be stored, cared for, and used, we conducted a survey among 1500 medical students at Poznan University of Medical Sciences. Our findings suggest that, while both religious and nonreligious students supported the idea of biobanking of human biological material and were willing to donate for research purposes, nonreligious students felt more positive toward biobanking, supported the idea of establishing biobanks in Poland more often, and were more eager to donate most types of tissues and to participate in biobank research. Religious beliefs were also associated with medical students' perception of benefits and risks resulting from biobanking, perceived trust toward various biobank institutions, and preferred type of consent.

[Determination of 2,4-dimethylhydroxybenzene by chromatographic methods in forensic toxicological research of biological material]. / Opredelenie 2,4-dimetilgidroksibenzola khromatograficheskimi metodami pri khimiko-toksikologicheskom issledovanii biologicheskogo materiala.

OBJECTIVE: Is to develop a method for determining 2.4-dimethylhydroxybenzene (2.4-DMHOB) in biological material. The analytical methods used in the experiments were extraction, column chromatography of normal pressure, TLC, GC-MS and HPLC. To extract the analyte from the bioactive matrix, maceration with the binary insulating agent acetone-ethyl acetate (3:7) was used, observing the 2:1 mass ratio of the «insulating agent-matrix¼. Optimal conditions of semi-preparative analyte chromatography were achieved in column (150×10 mm) of «Silasbor¼ S-18 sorbent in elution with a mixture of acetonitrile-water (7:3), which was used in the proposed cleaning scheme, combining extraction and reversed-phase column chromatography. The application of the mobile phase of tetrachloromethane-dioxane (9.5:0.5) has been substantiated for the selective determination of 2.4-DMHOB by TLC («Sorbfil¼ plates). The expediency of confirming identification of the analyte in the form of 2.4-dimethyltrymethylsilylphenol using GC-MS (DB-5MS EVIDEX column (25.000×0.2 mm), stationary phase (5%-phenyl)-methylpolysiloxane, carrier gas - helium) has been shown. The group of characteristic particles in the mass spectrum of trimethylsilyl analyte derivative was represented by 45; 59; 73; 82; 91; 105; 119; 135; 149; 163; 179; 194 m/z ions. HPLC (Discovery C18 250×4.6 mm column, eluting liquid - acetate buffer solution with pH 5.5 - acetonitrile, 50:50) was used to confirm the identification and quantification of 2.4-DMHOB. A method for determining 2.4-DMHOB by the HPLC method in biological material (liver tissue) is proposed, which corresponds to the criteria of linearity, selectivity, accuracy, precision and stability. The minimum detectable quantity of 2.4-DMHOB in the bioactive matrix is 0.5 µg/g, the minimum determined quantity is 1.2 ug/g.

Biobanking of human biological material and the principle of noncommercialisation of the human body and its parts.

The prohibition of commercialisation of the human body and its parts is not applied consistently and suffers from many exceptions in the human biological material (HBM) market. Examples include the possibility of patenting certain HBM-derived products and their commercial marketing or payments for blood donations. Thus, the current practice of marketing HBM-derived products makes the altruistic donor most vulnerable to exploitation while being deprived of benefits. There seem to be two ways to improve this state of affairs. The first is to apply consistently the prohibition of commercialisation of the body and its parts to commercially marketed tissue and cell products as well. This would require limiting the possibility of financial gain associated with the processing, distribution and sale of HBM-based products. Such a solution, however, does not seem to gain wide acceptance or have a chance of implementation in the near future. Therefore, introducing more transparent rules and greater donor empowerment seems more reasonable by exempting HBM from the ban on commercialisation under certain conditions and with clear limitations.

LEGAL REGULATION OF THE INSTITUTE OF TRANSPLANTATION IN UKRAINE.

OBJECTIVE: The aim: The aim of the study is to generalize the established by scientists features of the legal regulation of the institute of transplantation in Ukraine and other countries. PATIENTS AND METHODS: Materials and methods: The article examines the institute of transplantation, its medico-legal character, and the problems of implementing the institute in Ukraine. In the study, the authors applied general scientific methods, which include system analysis, system modeling, dialectical method. The authors used the following materials: laws, decrees of the President of Ukraine, resolutions of the government and ministries of healthcare, dissertations and articles by scientists, assessments of leading experts in the field. CONCLUSION: Conclusions: Theoretically, the legal aspect of the study of the institute of transplantation is important for formulating the general patterns of its emergence, developing prospects for its functioning and strategic directions for its further development, building a system for protecting the rights of all participants in this legal relationship. Different aspects of transplantation can be considered separately: medical or surgical; biological; psychological. But there is an equally important aspect - the legal one, which reveals the institute of transplantation from the standpoint of the protection of human dignity.

Scanning transmission X-ray microscopy study of subcellular granules in human platelets at the carbon K- and calcium L2,3-edges.

Platelets and their subcellular components (e.g., dense granules) are essential components in hemostasis. Understanding their chemical heterogeneities at the sub-micrometer scale, particularly their activation during hemostasis and production of platelet-derived extracellular vesicles, may provide important insights into their mechanisms; however, this has rarely been investigated, mainly owing to the lack of appropriate chemical characterization tools at nanometer scale. Here, the use of scanning transmission X-ray microscopy (STXM) combined with X-ray absorption near edge structure (XANES) to characterize human platelets and their subcellular components at the carbon K-edge and calcium L2,3-edge, is reported. STXM images can identify not only the spatial distribution of subcellular components in human platelets, such as dense granules (DGs) with sizes of ~200 nm, but also their granule-to-granule chemical heterogeneities on the sub-micrometer scale, based on their XANES spectra. The calcium distribution map as well as the principal component analysis of the STXM image stacks clearly identified the numbers and locations of the calcium-rich DGs within human platelets. Deconvolution of the carbon K-edge XANES spectra, extracted from various locations in the platelets, showed that amide carbonyl and carboxylic acid functional groups were mainly found in the cytoplasm, while ketone-phenol-nitrile-imine, aliphatic, and carbonate functional groups were dominant in the platelet DGs. These observations suggest that platelet DGs are most likely composed of calcium polyphosphate associated with adenosine triphosphate (ATP) and adenosine diphosphate (ADP), with significant granule-to-granule variations in their compositions, while the cytoplasm regions of platelets contain significant amounts of proteins.

Nanolatticed Architecture Mitigates Damage in Shark Egg Cases.

Structural versatility and multifunctionality of biological materials have resulted in countless bioinspired strategies seeking to emulate the properties of nature. The nanostructured egg case of swell sharks is one of the toughest permeable membranes known and, thus, presents itself as a model system for materials where the conflicting properties, strength and porosity, are desirable. The egg case possesses an intricately ordered structure that is designed to protect delicate embryos from the external environment while enabling respiratory and metabolic exchange, achieving a tactical balance between conflicting properties. Herein, structural analyses revealed an enabling nanolattice architecture that constitutes a Bouligand-like nanoribbon hierarchical assembly. Three distinct hierarchical architectural adaptations enhance egg case survival: Bouligand-like organization for in-plane isotropic reinforcement, noncylindrical nanoribbons maximizing interfacial stress distribution, and highly ordered nanolattices enabling permeability and lattice-governed toughening mechanisms. These discoveries provide fundamental insights for the improvement of multifunctional membranes, fiber-reinforced soft composites, and mechanical metamaterials.

Improving the Efficiency of Organic Solar Cells with Methionine as Electron Transport Layer.

Interface modification is an important way to get better performance from organic solar cells (OSCs). A natural biomolecular material methionine was successfully applied as the electron transport layer (ETL) to the inverted OSCs in this work. A series of optical, morphological, and electrical characterizations of thin films and devices were used to analyze the surface modification effects of methionine on zinc oxide (ZnO). The analysis results show that the surface modification of ZnO with methionine can cause significantly reduced surface defects for ZnO, optimized surface morphology of ZnO, improved compatibility between ETL and the active layer, better-matched energy levels between ETL and the acceptor, reduced interface resistance, reduced charge recombination, and enhanced charge transport and collection. The power conversion efficiency (PCE) of OSCs based on PM6:BTP-ec9 was improved to 15.34% from 14.25% by modifying ZnO with methionine. This work shows the great application potential of natural biomolecule methionine in OSCs.

A Novel Gelatin-Based Sustained-Release Molluscicide for Control of the Invasive Agricultural Pest and Disease Vector Pomacea canaliculata.

Pomacea canaliculata, one of the 100 most destructive invasive species in the world, and it is an important intermediate host of Angiostrongylus cantonensis. The molluscicides in current use are an effective method for controlling snails. However, most molluscicides have no slow-release effect and are toxic to nontarget organisms. Thus, these molluscicides cannot be used on a large scale to effectively act on snails. In this study, gelatin, a safe and nontoxic substance, was combined with sustained-release molluscicide and was found to reduce the toxicity of niclosamide to nontarget organisms. We assessed the effects of gelatin and molluscicide in controlling P. canaliculata snails and eggs. The results demonstrated that the niclosamide retention time with 1.0% and 1.5% gelatin sustained-release agents reached 20 days. Additionally, the mortality rate of P. canaliculata and their eggs increased as the concentration of the niclosamide sustained-release agents increased. The adult mortality rate of P. canaliculata reached 50% after the snails were exposed to gelatin with 0.1 mg/L niclosamide for 48 h. The hatching rate of P. canaliculata was only 28.5% of the normal group after the treatment was applied. The sustained-release molluscicide at this concentration was less toxic to zebrafish, which means that this molluscicide can increase the safety of niclosamide to control P. canaliculata in aquatic environments. In this study, we explored the safety of using niclosamide sustained-release agents with gelatin against P. canaliculata. The results suggest that gelatin is an ideal sustained-release agent that can provide a foundation for subsequent improvements in control of P. canaliculata.

[Amlodipine assay conditions and stability in biological material]. / Izuchenie uslovii opredeleniya i kharaktera ustoichivosti amlodipina v biologicheskom materiale.

The objective of the study is to determine amlodipine assay conditions and stability in biological material. Thin layer chromatography (TLC), gas chromatography-mass spectrometry (GC-MS) and UV-spectrophotometry were used for identification. Amlodipine was recovered from biomaterial by double (30 min each) infusing with acetone at the ratio of recovery solution and sample 2:1 (w/w). The purification was carried out by extraction and chromatography in a semi-preparative column with reverse-phase packing material Silasorb C-18 using acetone/water eluent (8:2). Amlodipine assay was performed by TLC [Sorbfil plates, butanol/acetone (5:5) as a mobile phase], GC-MS (HP-5 ms Ultra inert column (30 m×0.25×0.25 µm) with stationary phase of 5% phenyl-95% dimethyl polysiloxane), UV-spectrophotometry (95% ethanol as a solvent). The proposed assay method for amlodipine in biomaterial (liver tissue) is validated for linearity, selectivity, accuracy and precision. The amlodipine stability in model mixtures with liver tissue was studied. It was shown that the analyte stability in biological material decreases with increasing temperature. Amlodipine is stable at -25 °C, 0-2 °C, 8-10 °C, 18-22 °C, and 36 °C for 120, 112, 105, 91, and 77 days, respectively.

Effect of different types of dry swabs and their storage conditions on the inoculation of Corynebacterium diphtheriae.

The results of evaluating the effectiveness of C. diphtheriae inoculation using different types of dry swabs in studies simulating various conditions of its storage at the preanalytical stage of a laboratory study for diphtheria are presented. A typical toxigenic strain of C. diphtheriae biovar gravis No. 665 was used. A commercial dry, sterile cotton swab probe (Ningbo Greetmed Medical Instruments Co., LTD, China), a commercial dry, sterile swab probe (plastic and viscose) (COPAN, Italy), tufters with a fluffy probe-tampon on a polystyrene applicator, standard (DELTALAB, SL, Spain). The tampons were pooled with a 24-hour bacterial culture of C. diphtheriae, then immediately seeded on Tellurite-containing blood agar and Corynebacagar. Storage conditions were simulated for 3 hours: at room conditions +(20-25)°C, in the refrigerator +(4-8)°C, in a thermostat +(37±1)°C. Optimal storage of C. diphtheriae on all three types of dry swabs at + (4-8) ° C; at +(20-25)° C - growth is observed when seeding from a cotton swab; in a swab with a fleecy probe-tampon, a decrease in the inoculation of C. diphtheriae was noted; when using a viscose swab - a significant loss of C. diphtheriae. At +(37±1)°C, a significant decrease in the inoculation of C. diphtheriae on all three types of tampons was noted, up to the absence of growth when using a viscose tampon. To exclude the loss of C. diphtheriae, it is necessary to observe the conditions for taking and storing biological material at the preanalytical stage of a laboratory study, which will improve the quality of laboratory microbiological studies for diphtheria infection.

[Potential for the use of cards for sampling and transportation of biological material during forensic chemical and toxicological examinations]. / Vozmozhnost' ispol'zovaniya kart dlya zabora i transportirovki biologicheskogo materiala pri sudebno-khimicheskom i khimiko-toksikologicheskom issledovaniyakh.

The objective of the study is to evaluate the potential for the use of cards for sampling and transportation of biological material during forensic chemical and toxicological examinations by the example of a biological sample, urine containing zopiclone. Two methods of sample preparation were compared. The use of cards for the collection and transportation of biological material, such as urine, followed by high-resolution high-performance liquid chromatography-mass spectrometry (HPLC-MS) for the identification of zopiclone metabolites was shown to be beneficial in forensic chemical and toxicological examination. The validation evaluation of the proposed sample preparation and identification method met the acceptance criteria.

[Features of assay and decomposition dynamics of 2-methoxy-4-(1-propenyl)hydroxybenzene in biological material]. / Osobennosti opredeleniya i dinamiki razlozheniya 2-metoksi-4-(1-propenil)gidroksibenzola v biologicheskom materiale.

The objective was to study the features of assay and dynamics of decomposition of 2-methoxy-4-(1-propenyl)hydroxybenzene in biological material. Extraction, semi-preparation chromatography, TLC, HPLC, GC-MS and UV-spectrophotometry were used as test methods. 2-Methoxy-4-(1-propenyl)hydroxybenzene was extracted from the biological material by double infusion (45 min each) with ethyl acetate at a 2:1 mass ratio of isolating agent and biomatrix. Purification was performed by extraction and chromatography in a semi-preparative (190×10 mm) L 40/100 µm silica gel column using a hexane-dioxane (7:3) eluent. The analyte was determined by TLC methods (Sorbfil plates, hexane-acetone 9:1 as a mobile phase), HPLC [Discovery C18 HPLC Column (250×4.6 mm), acetonitrile-acetate buffer pH 5.5 (5:5) as a mobile phase], GC-MS [DB-5MS EVIDEX (25 m×0.2 mm) column with 5%-phenyl-95% dimethyl polysiloxane as a stationary phase], UV-spectrophotometry (95% ethanol as a solvent). The proposed assay method for 2-methoxy-4-(1-propenyl)hydroxybenzene in biomaterial (liver tissue) is validated for linearity, selectivity, accuracy and precision. The study results showed that the decomposition rate of the analyte increases as the store temperature increases. At 0-2 °C, 8-10 °C and 18-22 °C 2-methoxy-4-(1-propenyl)hydroxybenzene is stable for 480, 390 and 260 days respectively.

Effectiveness of using liquid transport media in bacteriological diagnostics of diphtheria infection.

The results of evaluating the effectiveness of the use of liquid transport media at the preanalytical stage of bacteriological diagnosis of diphtheria infection are presented. A typical toxigenic strain of C. diphtheriae biovar gravis № 665 was used. The experiments were carried out using a laboratory-prepared medium based on GRM-broth (State research center for applied biotechnology and microbiology, Obolensk), a transport system with a fleecy probe swab (DELTALAB) and a transport system ∑-Transwab ® with a polyurethane Sigma-swab (Medical Wire & Equipment Co. (Bath) Ltd.). The tampons were pooled with a 24-hour bacterial culture of C. diphtheriae, then immediately seeded on Tellurite-containing blood agar. Storage conditions were simulated for 6-24 hours: at room conditions +(20-25)° C, in the refrigerator +(4-8)° C, in a thermostat +(37±1)° C. Storage of C. diphtheriae was most optimal on two liquid transport systems in a refrigerator +(4-8)° C for 6 and 24 hours; in room conditions +(20-25)° C - there was a decrease in seeding after 6 hours and loss of pathological material after 24 hours, more pronounced on a fleecy probe swab; under thermostat conditions +(37±1)° C on both transport systems, a decrease in seeding was noted after 6 hours and a complete loss of pathological material after 24 hours. The results obtained demonstrated the efficiency of using the Amies liquid transport medium and justify the need to develop a domestic analogue of the transport system based on the Amies liquid medium for the bacteriological diagnosis of diphtheria infection.

[Study of the stability of 2-methoxy-4-(2-propenyl) hydroxybenzene in biological material]. / Izuchenie ustoichivosti 2-metoksi-4-(2-propenil) gidroksibenzola v biologicheskom materiale.

The purpose of this work is to study the stability of 2-methoxy-4-(2-propenyl)hydroxybenzene [2-MO-4-(2-P)HOB] in biological material. For analysis, gas chromatography-mass spectrometry (GC-MS) was used: column DB-5MS EVIDEX (25 m × 0.2 mm) with a stationary phase of 5%-phenyl-95%-dimethylpolysiloxane; thin layer chromatography (TLC): Sorbfil plates, hexane-dioxane-propanol-2 mobile phase (40:5:1) and UV spectrophotometry (solvent - 95% ethanol). 2-MO-4-(2-P)HOB was isolated from the biomatrix (liver tissue) by infusion with a mixture of ethyl acetate-acetone (7:3). Purification of the analyte was carried out by combining extraction (water-ethyl acetate system) and semi-preparative column chromatography [sorbent - silica gel L 40/100 µm, eluent - hexane-dioxane (8.5:1.5)]. It was established that at -22 °C, 4 °C, 12 °C, 20 °C and 30 °C 2-MO-4-(2-P)HOB is stored in the liver tissue for 385, 357, 301, 245 and 217 days, respectively. We studied the possibility of mathematical description of the dynamics of analyte decomposition in a biomaterial (liver tissue) at the indicated temperatures using the hyperbolic equation. The coefficients in the hyperbola equation (kav), calculated according to the results of the experiment, for temperatures of -22 °C, 4 °C, 12 °C, 20 °C and 30 °C amounted to 6223, 3036, 2387, 1903 and 932, respectively., which is described by the equation: kav=101.19∙(50-to)-1272.78. It was established that on the basis of this equation it is possible to predict the nature of the stability of 2-MO-4-(2-P)HOB in the biomaterial (liver tissue) at temperatures in the range from -22 °C to 30 °C.

The spider cuticle: a remarkable material toolbox for functional diversity.

Engineered systems are typically based on a large variety of materials differing in composition and processing to provide the desired functionality. Nature, however, has evolved materials that are used for a wide range of functional challenges with minimal compositional changes. The exoskeletal cuticle of spiders, as well as of other arthropods such as insects and crustaceans, is based on a combination of chitin, protein, water and small amounts of organic cross-linkers or minerals. Spiders use it to obtain mechanical support structures and lever systems for locomotion, protection from adverse environmental influences, tools for piercing, cutting and interlocking, auxiliary structures for the transmission and filtering of sensory information, structural colours, transparent lenses for light manipulation and more. This paper illustrates the 'design space' of a single type of composite with varying internal architecture and its remarkable capability to serve a diversity of functions. This article is part of the theme issue 'Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 1)'.

Nanoscale Material Heterogeneity of Glowworm Capture Threads Revealed by AFM.

Adhesive materials used by many arthropods for biological functions incorporate sticky substances and a supporting material that operate synergistically by exploiting substrate attachment and energy dissipation. While there has been much focus on the composition and properties of the sticky glues of these bio-composites, less attention has been given to the materials that support them. In particular, as these materials are primarily responsible for dissipation during adhesive pull-off, little is known of the structures that give rise to functionality, especially at the nano-scale. In this study we used tapping mode atomic force microscopy (TM-AFM) to analyze unstretched and stretched glowworm (Arachnocampa tasmaniensis) capture threads and revealed nano-scale features corresponding to variation in surface structure and elastic modulus near the surface of the silk. Phase images demonstrated a high resolution of viscoelastic variation and revealed mostly globular and elongated features in the material. Increased vertical orientation of 11-15 nm wide fibrillar features was observed in stretched threads. Fast Fourier transform analysis of phase images confirmed these results. Relative viscoelastic properties were also highly variable at inter- and intra-individual levels. Results of this study demonstrate the practical usefulness of TM-AFM, especially phase angle imaging, in investigating the nano-scale structures that give rise to macro-scale function of soft and highly heterogeneous materials of both natural and synthetic origins.

MEDICAL EXPERIMENTS IN THE LIGHT OF THE AMENDMENT OF THE ACT ON THE PROFESSION OF A PHYSICIAN AND A DENTIST.

On the 1st of January 2021 the new legal regulations to the Act of 5 December 1996 on the professions of a physician and a dentist came into force. The aim of this article is to present the new legal regulations of conducting medical experiments and to clarify the regulations already applicable. Under the amended regulations, the legislator, comprehensively regulated the legal conditions and rules to conduct the medical experiments, both research experiments and therapeutic ones, by imposing the new restrictions on a person who conducts medical experiments. The most significant change is that examination of biological material, including genetic material collected from a person for scientific purposes, is also regarded as a medical experiment. The purpose of the article is therefore to familiarize medical community with the new legal regulations concerning the principles of conducting all kind of medical experiments and to point out what interpretation doubts and legal dilemmas may arise while their conducting.