Polymeric Microcapsules Research Articles

Magnetically Separable Chiral Poly(ionic liquid) Microcapsules Prepared Using Oil-in-Oil Emulsions.

This article presents a method for producing chiral ionic liquid-based polyurea microcapsules that can be magnetically separated. The method involves entrapping hydrophilic magnetic nanoparticles within chiral polyurea microspheres. The synthetic process for creating these magnetic polyurea particles involves oil-in-oil (o/o) nano-emulsification of an ionic liquid-modified magnetite nanoparticle (MNPs-IL) and an ionic liquid-based diamine monomer, which comprises a chiral bis(mandelato)borate anion, in a nonpolar organic solvent, toluene, and contains a suitable surfactant. This is followed by an interfacial polycondensation reaction between the isocyanate monomer, polymethylenepolyphenyl isocyanate (PAPI 27), and the chiral diamine monomer, which generates chiral polyurea microcapsules containing magnetic nanoparticles within their cores. The microcapsules generated from the process are then utilized to selectively adsorb either the R or S enantiomer of tryptophan (Trp) from a racemic mixture that is dissolved in water, in order to evaluate their chiral recognition capabilities. During the experiments, the magnetically separable chiral poly(ionic liquid) microcapsules, which incorporated either the R or S isomer of chiral bis(mandelato)borate, exhibited exceptional enantioselective adsorption performance. Thus, the chiral polymeric microcapsules embedded with the R-isomer of the bis(mandelato)borate anion demonstrated significant selectivity for adsorbing L-Trp, yielding a mixture with 70% enantiomeric excess after 96 h. In contrast, microcapsules containing the S-isomer of the bis(mandelato)borate anion preferentially adsorbed D-Trp, achieving an enantiomeric excess of 73% after 48 h.

Encapsulation and controlled release of concentrated hydrochloric acid using tunable polymeric microcapsules

While acids have numerous applications in various industries, their usage presents challenges, such as safety risks, environmental impact, and corrosion of equipment. Encapsulation is a versatile technique that involves the containment of acid substances within a protective shell. It offers an innovative solution to mitigate these challenges and provide controlled release and targeted delivery of acid substances. In this work, we propose the encapsulation of concentrated hydrochloric acid using microfluidic devices to ensure the production of monodisperse microcapsules with controlled and tunable features. Two polymers were used as shell materials: polydimethylsiloxane and poly (methyl methacrylate). The release of the encapsulated acid was triggered by osmotic pressure difference between the inner and outer phases. Results elucidate that release time can be controlled by tuning the capsules’ shell material, thickness, stiffness, and eccentricity. The enhanced control over concentrated mineral acids release enabled by microfluidics is remarkably relevant for a wide range of industrial applications.

Synthesis of polymeric microcapsules filled with castor oil to enhance tribological properties in epoxy resin

Synthesis of polymeric microcapsules filled with castor oil to enhance tribological properties in epoxy resin

Photoactivated Cyclic Polyphthalaldehyde Microcapsules for Payload Delivery.

Microcapsules with a cyclic polyphthalaldehyde (cPPA) shell and oil core were fabricated by an emulsification process. The low ceiling temperature cPPA shell was made phototriggerable by incorporating a photoacid generator (PAG). Photoactivation of the PAG created a strong acid which catalyzed cPPA depolymerization, resulting in the release of the core payload, as quantified by 1H NMR. The high molecular weight cPPA (197 kDa) yielded uniform spherical microcapsules. The core diameter was 24.8 times greater than the cPPA shell thickness (2.4 to 21.6 μm). Nonionic bis(cyclohexylsulfonyl)diazomethane (BCSD) and N-hydroxynaphthalimide triflate (HNT) PAGs were used as the PAG in the microcapsule shells. BCSD required dual stimuli of UV radiation and post-exposure baking at 60 °C to activate cPPA depolymerization while room temperature irradiation of HNT resulted in instantaneous core release. A 300 s UV exposure (365 nm, 10.8 J/cm2) of the cPPA/HNT microcapsules resulted in 66.5 ± 9.4% core release. Faster core release was achieved by replacing cPPA with a phthalaldehyde/propanal copolymer. A 30 s UV exposure (365 nm, 1.08 J/cm2) resulted in 82 ± 13% core release for the 75 mol % phthalaldehyde/25 mol % propanal copolymer microcapsules. The photoresponsive shell provides a versatile polymer microcapsule technology for on-demand, controlled release of hydrophobic core payloads.

Fabrication of bio-based polymer microcapsule containing fragrances via interfacial photo-initiated crosslinking

Home fragrance (F) products such as laundry detergent and fabric softener use fragrance or essential oils as key components. Typically, the fragrance is enclosed within a polymer. The shell enhances the longevity of the scent due to its durability. However, there is growing environmental concern about utilizing fossil polymers, which decompose slowly and harm the ecology and food chain. Biopolymers are also highly expected to be used as alternative polymers to prepare environmentally friendly microcapsules. This research aims to use poly cinnamyl methacrylate (PCMA) as a biopolymer to prepare microcapsules encapsulated fragrance via interfacial photo-initiated crosslinking. The CMA monomer was prepared by the esterification of cinnamyl alcohol with methacrylic anhydride and synthesized via radical polymerization to form PCMA with a molecular weight of 6,400 g/mol. The PCMA and PCMA/F particles were obtained when the PCMA and PCMA/F droplets dispersed in water were UV-irradiated at 60 W for 8h, giving PCMA and PCMA/F particles contained the highest crosslinking (60–75%). Both PCMA and PCMA/F particles were spherical and smooth outer surfaces where their particle sizes of ∼2 and 7 µm for PCMA and PCMA/F particles were obtained, respectively. The larger size of PCMA/F particles was due to encapsulation, where the encapsulation efficiency of fragrance in PCMA/F particles was approximately 100%. Moreover, the fragrances remaining in the microcapsule particles after 40 days of storage were over 90%. This technique was simple, had high potential microencapsulation, and was environmentally friendly, so the developed microcapsules would express great potential for textiles and laundry formulations.

Temperature-sensitive fragrance-releasing polymeric microcapsules

This research aimed to control release of fragrance using thermally-actuated microcapsules so that the release rate shows a considerable change at a certain temperature. Accordingly, four different polymers, namely, two grades of poly(methyl methacrylate) having different molecular weight as well as two poly[(methyl methacrylate)–co-(2-ethylhexyl acrylate)] copolymers, which were synthesized in this work, were designated as capsules’ shell. Number-average molecular weight of the copolymers and one of the two used PMMA grades was in the range of 47 to 56 kDa while that of the other PMMA grade was 344 kDa. Furthermore, Tg of the lower molecular weight grade PMMA and the two copolymers was determined as 119.3, 72.2 and 66.3 °C, respectively, using DSC experiments. Subsequently, R-Limonene as a model fragrance, was encapsulated by either of the polymers using solvent evaporation method. Effect of various parameters, including molecular weight and Tg of the shell polymer and concentration of emulsifier, on morphological characteristics of the microcapsules were investigated. Using two microscopic techniques, it was observed that increment of molecular weight of shell polymer enhances microcapsules’ size, shell thickness and porosity. Moreover, elevation of emulsifier concentration to a certain value of 1.5 wt% was shown to lessen size and porosity of microcapsules. The fragrance release profiles were determined and fitted to several mathematical models, proving that at least one more mechanism, in addition to diffusion, is involved in the release, which was attributed to capillary effects in the shell pores. Moreover, a pronounced increase in release rate upon elevation of temperature from 5 to 15 °C was observed for either of the copolymer shells. The effect was ascribed to remarkable strengthening of segmental mobility of the copolymers due to elevation of temperature and can be regarded as a promising way for the fabrication of smart microcapsules capable of thermal controlling fragrance release.

Unraveling the detrimental effect of polymeric microcapsules on the corrosion performance of epoxy resin coatings

Organic micro- or nanocapsules are widely used as reservoirs to carry sealing agents or corrosion inhibitors to achieve the self-healing functionality of coatings. To understand the impact of the capsules' incorporation on the barrier properties of organic coatings, composite epoxy resin coatings containing different concentrations (e.g., 5 wt%, 10 wt% and 20 wt%) of urea-formaldehyde (PUF) microcapsules were deposited on the top of Q235 carbon steel. The features of PUF microcapsules and composite coatings were characterized, and the corrosion behaviors of the coating-protected carbon steel were investigated in NaCl solution. The results showed that the spherical PUF microcapsules (∼40 μm) with 290 nm thick shell and hexyl acetate core are synthesized through in situ polymerization. The prepared microcapsules can uniformly distribute within the epoxy resin coatings, which in turn deteriorates the corrosion resistance of the microcapsules-containing composite coatings (MCECs). Lower volume (5 wt%) microcapsules incorporation caused a slight reduction in the corrosion resistance (Rc) and effective capacitance (Ceff) from 4.39 × 107 Ω·cm−2 and 6.50 × 10−5 mF·cm−2 to 8.72 × 106 Ω·cm−2 and 5.63 × 10−5 mF·cm−2, respectively. For higher volume (10 wt% and 20 wt%) groups, the Rc further decreases to 7.47 × 105 Ω·cm−2 and 1.45 × 105 Ω·cm−2, whereas the Ceff increases to 5.63 × 10−5 mF·cm−2 and 5.63 × 10−5 mF·cm−2, respectively. The failure mechanism of the MCECs can be ascribed to the rupture of the PUF microcapsules during the curing process and/or immersion in NaCl electrolyte, which suggested the mechanical strength and chemical stability of the capsules should be carefully determined to avoid their negative impact on the barrier property of polymeric coatings.

A microfluidic platform for the synthesis of polymer and polymer-protein-based protocells

In this study, we demonstrate the fabrication of polymersomes, protein-blended polymersomes, and polymeric microcapsules using droplet microfluidics. Polymersomes with uniform, single bilayers and controlled diameters are assembled from water-in-oil-in-water double-emulsion droplets. This technique relies on adjusting the interfacial energies of the droplet to completely separate the polymer-stabilized inner core from the oil shell. Protein-blended polymersomes are prepared by dissolving protein in the inner and outer phases of polymer-stabilized droplets. Cell-sized polymeric microcapsules are assembled by size reduction in the inner core through osmosis followed by evaporation of the middle phase. All methods are developed and validated using the same glass-capillary microfluidic apparatus. This integrative approach not only demonstrates the versatility of our setup, but also holds significant promise for standardizing and customizing the production of polymer-based artificial cells.Graphical

Оценка накопления полимерных субмикронных микрокапсул в клеточном и межклеточном пространствах 3D сфероидов

Multicellular spheroids are three-dimensional in vitro models of organs and tissues. Multicellular spheroids have gained great interest in the field of biotechnology as they are reproducible and mimic real organs and tissues so can be used as test systems for new forms of drugs, allowing minimizing the use of in vivo animal models. Flow cytometry was used to describe the accumulation of submicron polymeric microcapsules in cellular spheroids, which allowed us to identify the main aspects of drug carrier-cell interactions within the spheroid. Spheroids were generated using 4T1 mouse breast cancer cells and healthy L929 mouse fibroblast cells. The arrangement of microcapsules with 300, 500, 1000 nm diameter with biocompatible shells in cell spheroids was evaluated in their intercellular and intracellular spaces.

Functionalized Calcium Carbonate-Based Microparticles as a Versatile Tool for Targeted Drug Delivery and Cancer Treatment.

Nano- and microparticles are increasingly widely used in biomedical research and applications, particularly as specific labels and targeted delivery vehicles. Silica has long been considered the best material for such vehicles, but it has some disadvantages limiting its potential, such as the proneness of silica-based carriers to spontaneous drug release. Calcium carbonate (CaCO3) is an emerging alternative, being an easily available, cost-effective, and biocompatible material with high porosity and surface reactivity, which makes it an attractive choice for targeted drug delivery. CaCO3 particles are used in this field in the form of either bare CaCO3 microbeads or core/shell microparticles representing polymer-coated CaCO3 cores. In addition, they serve as removable templates for obtaining hollow polymer microcapsules. Each of these types of particles has its specific advantages in terms of biomedical applications. CaCO3 microbeads are primarily used due to their capacity for carrying pharmaceutics, whereas core/shell systems ensure better protection of the drug-loaded core from the environment. Hollow polymer capsules are particularly attractive because they can encapsulate large amounts of pharmaceutical agents and can be so designed as to release their contents in the target site in response to specific stimuli. This review focuses first on the chemistry of the CaCO3 cores, core/shell microbeads, and polymer microcapsules. Then, systems using these structures for the delivery of therapeutic agents, including drugs, proteins, and DNA, are outlined. The results of the systematic analysis of available data are presented. They show that the encapsulation of various therapeutic agents in CaCO3-based microbeads or polymer microcapsules is a promising technique of drug delivery, especially in cancer therapy, enhancing drug bioavailability and specific targeting of cancer cells while reducing side effects. To date, research in CaCO3-based microparticles and polymer microcapsules assembled on CaCO3 templates has mainly dealt with their properties in vitro, whereas their in vivo behavior still remains poorly studied. However, the enormous potential of these highly biocompatible carriers for in vivo applications is undoubted. This last issue is addressed in depth in the Conclusions and Outlook sections of the review.

Preparation and evaluation of polymer microcapsules with self-healing for use in a polyurethane matrix. Preliminary studies

Preparation and evaluation of polymer microcapsules with self-healing for use in a polyurethane matrix. Preliminary studies

Encapsulation of beetroot extract (Beta vulgaris L.) obtained by internal and external ionic gelation: a comparative study

Natural pigments, like betalains found in beets, are sensitive to environmental conditions, which may impact their reactivity and shelf-life. Microencapsulation is an attractive alternative for delivering these compounds, offering protection through polymeric microcapsules. The aim of this study was to compare two ionic gelation methodologies, external (EG) and internal gelation (IG), in the microencapsulation of beet aqueous extract. Particles were obtained by mixing sodium alginate with the aqueous extract of beetroot and crosslinking with calcium chloride solution using the extrusion method. Encapsulation characteristics and physical, morphological features were evaluated. The particles showed 10.72 and 89.90% encapsulation efficiency for EG and IG, respectively. Loading capacity was 18.90% for EG and 25.60% for IG. Those IG particles showed superior water absorption capacity during rehydration. Texture analysis indicated that EG particles showed greater hardness. Release kinetics indicated that EG particles followed the Korsmeyer-Peppas model, while IG particles followed the Higuchi model. Thus, the appropriate encapsulation technique should be selected depending on the food matrix to be used and the specific objective of delivering the active encapsulated molecules.

Optimization of synthesis parameters of PUF/ENB microcapsules for self‐healing applications using factorial design methodology

AbstractThis study introduces a systematic experimental approach aimed at enhancing the production process of poly(urea‐formaldehyde) (PUF) microcapsules filled with 5‐ethylidene‐2‐norbonene (ENB) using in situ emulsion polymerization. Essential parameters were identified through a prior Plackett Burman (PB) design, leading to the implementation of a 24‐1 fractional factorial design. The key parameters selected encompassed stirring speed, poly(ethylene‐alt‐maleic anhydride) (EMA) emulsifier content, pH of the reaction, and the quantity of 1‐octanol. Optimal conditions for polymeric microcapsule synthesis were determined using a statistical analysis of the complete factorial design, facilitating the development of representative mathematical models for the process. A comprehensive evaluation of response variables including microcapsule diameter, yield, encapsulated content, stability, and thermal degradation was conducted. Utilizing response surface analysis (RSM), it was determined that the PUF/ENB(2C) condition (stirring at 700 rpm, a reaction pH of 3.0, and EMA content of 0.425 g) resides within the optimized synthesis region, producing microcapsules exhibiting favorable morphological characteristics, yield of 52% and encapsulated content of 80%.

P/N/S-containing cellulose nanofibrils enable curcumin encapsulation via Pickering emulsion based microcapsules

Renewable polymeric microcapsules hold promise for precisely controlled release of hydrophobic drugs (curcumin) in therapeutic treatment. However, there still remains challenges to stabilize the properties of microcapsules and to enhance encapsulation efficiencies of curcumin. By using an eco-friendly ternary deep eutectic solvent here, we successfully fabricated native cellulose nanofibrils, holocellulose nanofibrils, and lignocellulose nanofibrils containing both phytates and sulfate groups. In addition, a novel type of curcumin-loaded polymeric microcapsules with diameter of 10–20 μm were prepared by cellulose nanofibrils as stabilizing agents in Polylactide Pickering emulsion. The Pickering emulsions stabilized by P/N/S-containing cellulose nanofibrils, holocellulose nanofibrils, and lignocellulose nanofibrils are more stable than the unmodified cellulose nanofibrils-stabilized emulsion. The Pickering emulsion stabilized by 0.2 wt% P/N/S-containing lignocellulose nanofibrils exhibited the highest emulsion layer height and the zeta potential reached −39.74 ± 2.88 mV. Moreover, the highest encapsulation efficiency of curcumin can be up to 94.80%. Antimicrobial test revealed that curcumin in the polymeric microcapsules exhibited an excellent inhibitory effect on S. aureus and the antibacterial efficiency reached 98.66%. These results provided important information on the comparison of different cellulose nanofibrils-stabilized Pickering emulsions and the application of controlled release of curcumin incorporated polymeric microcapsules in drug delivery system.

A flexible modulated pesticide release platform through poly(urethane-urea) microcapsules: effect of different crosslinkers compositions.

Polymeric microcapsules (MCs) have become an important issue and have attracted increasing attention because of their tunable physical and chemical properties. Diverse shell structures can confer multiple properties on MCs. Different polyols (1,4-butanediol and glycerin) and polyamines (triethylenetetramine and isophorondiamine) were selected as crosslinkers to obtain emamectin benzoate (EB)-loaded poly(urethane-urea) MCs (PU-MCs) by interfacial polymerization. The four obtained PU-MCs showed sphericity with different degrees of smoothness on their surfaces, and displayed a uniform size distribution ranging from 500 to 700 nm. Moreover, transmission electron microscopy showed that the shell thickness was roughly uniform, and was greatly influenced by the type and structure of the crosslinker. GI-MCs, prepared using glycerin and isophorondiamine, had the largest shell thickness. GT-MCs, obtained using glycerin and triethylenetetramine, had the highest encapsulation efficiency and drug-loading content, and BT-MCs, obtained using mixtures of 1,4-butanediol and triethylenetetramine, had the fastest release behavior. Thermogravimetric analysis revealed that the greater the degree of shell crosslinking, the higher decomposition temperature and the greater the thermal stability. A BT-MC suspension had the lowest viscosity and contact angle with the best wettability. Bioassay experiments showed that BT-MCs exhibited good insecticidal activity against Plutella xylostella larvae with a half-maximal lethal concentration of 4.19 mg/L. Furthermore, a BT-MC suspension showed good thermal and light stability, with potential applications in minimizing the toxicity of EB through sustained release. Various properties of EB-loaded PU-MCs were modulated through simple selection of different polyols and polyamines during fabrication, which might have an important role in constructing the pesticide delivery system and improving pesticide utilization. © 2024 Society of Chemical Industry.

Facile encapsulation of cyanoacrylate-based bioadhesive by electrospray method and investigation of the process parameters

Polymer microcapsules containing cyanoacrylates have represented a promising option to develop self-healing biomaterials. This study aims to develop an electrospray method for the preparation of capsules using poly(methyl methacrylate) (PMMA) as the encapsulant and ethyl 2-cyanoacrylate (EC) as the encapsulate. It also aims to study the effect of the electrospray process parameters on the size and morphology of the capsules. The capsules were characterized using Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and field-emission scanning electron microscopy (FE-SEM). Moreover, the effects of electrospray process parameters on the size were investigated by Taguchi experimental design. FTIR and TGA approved the presence of both PMMA and EC without further reaction. FE-SEM micrograph demonstrated that an appropriate choice of solvents, utilizing an appropriate PMMA:EC ratio and sufficient PMMA concentration are critical factors to produce capsules dominantly with an intact and spherical morphology. Utilizing various flow rates (0.3–0.5 ml/h) and applied voltage (18–26 kV), capsules were obtained with a 600–1000 nm size range. At constantly applied voltages, the increase in flow rate increased the capsule size up to 40% (ANOVA, p ≤ 0.05), while at constant flow rates, the increase in applied voltage reduced the average capsule size by 3.4–26% (ANOVA, p ≤ 0.05). The results from the Taguchi design represented the significance of solution flow rate, applied voltage, and solution concentration. It was shown that the most effective parameter on the size of capsules is flow rate. This research demonstrated that electrospray can be utilized as a convenient method for the preparation of sub-micron PMMA capsules containing EC. Furthermore, the morphology of the capsules is dominated by solvents, PMMA concentration, and PMMA:EC ratio, while the average size of the capsules can be altered by adjusting the flow rate and applied voltage of the electrospray process.

Encapsulation and Characterization of Proanthocyanidin Microcapsules by Sodium Alginate and Carboxymethyl Cellulose.

Proanthocyanidins are important compounds known for their antioxidant and radical scavenging properties, but they are highly sensitive to light, heat, oxygen, and pH. In our study, proanthocyanidin was encapsulated using sodium alginate and carboxymethyl cellulose to enhance controlled release, pH stability, metal ion tolerance, temperature resistance, time release, the microencapsulation of food additives stability, antioxidant capacity analysis, and the storage period tolerance of proanthocyanidin. Fourier transforms infrared (FTIR) analysis and full-wavelength UV scanning indicated the successful immobilization of proanthocyanidins into the polymeric microcapsules. The flowability and mechanical properties of the microcapsules were enhanced. Moreover, proanthocyanidin microcapsules exhibited higher thermal, pH, metal ion, time, and microencapsulation food additive stability. In addition, due to their high antioxidant properties, the proanthocyanidin microcapsules retained a greater amount of proanthocyanidin content during the gastric phase, and the proanthocyanidin was subsequently released in the intestinal phase for absorption. Thus, the study provided a systematic understanding of the antioxidant capabilities and stability of proanthocyanidin microcapsules, which is beneficial for developing preservation methods for food additives.

Fabrication of composite polymer microcapsules via the supercritical extraction of Pickering emulsion Method: Insights into emulsification and extraction

Polyphenylene oxide (PPO)/cellulose nanocrystal (CNC)/carbon black (CB) microcapsules were fabricated by the supercritical extraction of Pickering emulsion (SFEPE) method. The effects of Pickering emulsion formulations on the emulsion properties, emulsification kinetics, and CPM properties were investigated. The phase behaviors in the supercritical extraction process were studied, and the mass transfer between the emulsion droplet and supercritical carbon dioxide (SCCO2) was also interpreted. The results indicate that CNC concentration, CB concentration, and NaCl concentration can decrease the droplet size and creaming index of emulsions, while the water–oil ratio can decrease the droplet size but enhance the creaming index. The emulsion formulations of water–oil > 3, CNC concentration > 0.25 mg/mL, CB concentration < 2.5 mg/mL, and NaCl concentration > 2.5 mg/mL are conducive to the emulsion formation and emulsification kinetics. For the supercritical extraction on Pickering emulsions, the operation conditions slightly above the mixture critical point (9 MPa at 313 K, for example) are proved to be conducive to the extraction.

Preparation and Characterization of Perfluoropolyether-Silane@Ethye Cellulose Polymeric Microcapsules.

A novel polymeric microcapsule was designed and synthesized using perfluoropolyether silane (PFPE-silane) as a superhydrophobic core material and ethyl cellulose (EC) as a shell material. The effects of the stirring rate and the core-to-shell ratio on the synthesized microcapsules were investigated. The physicochemical properties of the polymeric microcapsules were evaluated using scanning electron microscopy, fourier transform infrared spectroscopy, thermogravimetric analysis, laser particle size analysis, and wettability analysis. The results showed that when the stirring rate was 650 rpm and the core-to-shell ratio was 1:1, well-distributed and uniformly dispersed microcapsules could be obtained. The results also indicated that the prepared polymeric microcapsules were spherical particles with micropores on the surface, and they had an average particle size of 165.71 μm. The EC shells could effectively prevent the thermal decomposition of PFPE-silane during cement hydration, and the PFPE-silane also exhibited excellent hydrophobicity. The specially designed structure of this polymeric microcapsule suggests its potential for enhancing the corrosion resistance of reinforced concrete structures.

Effect of photoconversion conditions on the spectral and cytotoxic properties of photoconvertible fluorescent polymer markers.

Fluorescence labeling of cells is a versatile tool used to study cell behavior, which is of significant importance in biomedical sciences. Fluorescent photoconvertible markers based on polymer microcapsules have been recently considered as efficient and perspective ones for long-term tracking of individual cells. However, the dependence of photoconversion conditions on the polymeric capsule structure is still not sufficiently clear. Here, we have studied the structural and spectral properties of fluorescent photoconvertible polymeric microcapsules doped with Rhodamine B and irradiated using a pulsed laser in various regimes, and shown the dependence between the photoconversion degree and laser irradiation intensity. The effect of microcapsule composition on the photoconversion process was studied by monitoring structural changes in the initial and photoconverted microcapsules using X-ray diffraction analysis with synchrotron radiation source, and Fourier transform infrared, Raman and fluorescence spectroscopy. We demonstrated good biocompatibility of free-administered initial and photoconverted microcapsules through long-term monitoring of the RAW 264.7 monocyte/macrophage cells with unchanged viability. These data open new perspectives for using the developed markers as safe and precise cell labels with switchable fluorescent properties.