Polymer Microspheres Research Articles

Eco-friendly calcium alginate microspheres enable enhanced profile control and oil displacement

Polymer microspheres (PMs), such as polyacrylamide, have been widely applied for enhanced oil recovery (EOR), yet with environmental concerns. Here, we report a microfluid displacement technology containing a bio-based eco-friendly material, i.e., calcium alginate (CaAlg) microspheres for EOR. Two dominant mechanisms responsible for EOR over CaAlg fluid have been verified, including the microscopic oil displacement efficacy augmented by regulating capillary force (determined by the joint action of interfacial tension and wettability between different phases) and macroscopic sweep volume increment through profile control and mobility ratio reduction. This comprehensive effectiveness can be further impacted when the CaAlg microsphere is embellished ulteriorly by using appropriate amount of sodium dodecyl sulfonate (SDS). The core flooding and nuclear magnetic resonance (NMR) tests demonstrate that CaAlg-SDS microsphere can balance the interphase property regulation (wettability alteration and IFT reduction) and rheology properties, enabling simultaneous profile control and oil displacement. Excessive introduction of SDS will have a negative impact on rheological properties, which is not favored for EOR. Our results show that the involvement of 4-mM SDS will provide the best behavior, with an EOR rate of 34.38%. This cost-effective and environmentally-friendly bio-microsphere-based microfluidic displacement technology is expected to achieve “green” oil recovery in future oilfield exploitation.

Fast 19 F spectroscopic imaging with pseudo-spiral k-space sampling.

Fluorine MRI is finding wider acceptance in theranostics applications where imaging of 19 F hotspots of fluorinated contrast material is central. The essence of such applications is to capture ghosting-artifact-free images of the inherently low MR response under clinically viable conditions. To serve this purpose, this work introduces the balanced spiral spectroscopic imaging (BaSSI) sequence, which is implemented on a 3.0 T clinical scanner and is capable of generating 19 F hotspot images in an efficient manner. The sequence utilizes an all-phase-encoded pseudo-spiral k-space trajectory, enabling the acquisition of broadband (80 ppm) fluorine spectra free from chemical shift ghosting. BaSSI can acquire a 64 × 64 image with 1 mm × 1 mm voxels in just 14 s, significantly outperforming typical MRSI sequences used in 1 H or 31 P imaging. The study employed in silico characterization to verify essential design choices such as the excitation pulse, as well as to identify the boundaries of the parameter space explored for optimization. BaSSI's performance was further benchmarked against the 3D ultrashort-echo-time balanced steady-state free precession (3D UTE BSSFP) sequence, a well established method used in 19 F MRI, in vitro. Both sequences underwent extensive optimization through exploration of a wide parameter space on a small phantom containing 10 μL of non-diluted bulk perfluorooctylbromide (PFOB) prior to comparative experiments. Subsequent to optimization, BaSSI and 3D UTE BSSFP were employed to capture images of small non-diluted bulk PFOB samples (0.10 and 0.05 μL), with variations in the number of signal averages, and thus the total scan time, in order to assess the detection sensitivities of the sequences. In these experiments, the detection sensitivity was evaluated using the Rose criterion (Rc ), which provides a quantitative metric for assessing object visibility. The study further demonstrated BaSSI's utility as a (pre)clinical tool through postmortem imaging of polymer microspheres filled with PFOB in a BALB/c mouse. Anatomic localization of 19 F hotspots was achieved by denoising raw data obtained with BaSSI using a filter based on the Rose criterion. These data were then successfully registered to 1 H anatomical images. BaSSI demonstrated superior detection sensitivity in the benchmarking analysis, achieving Rc values approximately twice as high as those obtained with the 3D UTE BSSFP method. The technique successfully facilitated imaging and precise localization of 19 F hotspots in postmortem experiments. However, it is important to highlight that imaging 10 mM PFOB in small mice postmortem, utilizing a 48 × 48 × 48 3D scan, demanded a substantial scan time of 1 h and 45 min. Further studies will explore accelerated imaging techniques, such as compressed sensing, to enhance BaSSI's clinical utility.

Study of the Kinetics of Sorption and Desorption of Doxorubicin Hydrochloride by Polymer Microspheres

Introduction: One of the promising directions in the treatment of patients with malignant neoplasms is chemoembolization with microspheres, which consists in the local blocking of the blood flow by spherical particles and the release of a cytostatic drug by them in order to suppress the tumor. However, the pharmaceutical market is dominated by imported microspheres for embolotherapy, as a result of which they are characterized by a high cost. In this regard, the study of the properties of domestic embolisates is a popular topic for scientific research. Purpose: To study in vitro the kinetics of sorption and release of doxorubicin hydrochloride by polymeric microspheres of domestic production. Material and methods: Spectrophotometry was used to study the sorption kinetics and release of doxorubicin hydrochloride by polymeric microspheres. The appearance of the microspheres was examined by microscopy. Results and discussion: The study made it possible to establish the dependence of the rate of saturation of polymer microspheres «Sfera-Spektr» with doxorubicin hydrochloride on their size: the smaller the diameter of the microspheres, the faster they absorb the drug. The absence of dependence of the release rate of doxorubicin hydrochloride by polymeric microspheres on their size range was shown. Conclusion: The profiles of the sorption kinetics and the dynamics of the release of doxorubicin hydrochloride by polymeric microspheres have been established.

High Performance Shape Memory Epoxy Syntactic Foam Composites as Lost Circulation Material in Deep Drilling

AbstractLost circulation is a critical issue in drilling. This work reports the investigations on shape memory epoxy polymers (SMEPs) with high switching temperatures, and good thermal, mechanical and shape memory properties for plugging in deep drilling. The SMEPs are produced by curing diglycidyl ether of bisphenol A (DGEBA) and castor oil glycidyl ether (COGE) with a flexible poly(oxypropylene) diamine (D230) and a rigid 4, 4′ ‐diaminodiphenyl methane (DDM). Increasing D230 contents or using COGE, glass transition temperature (Tg, 93–163 °C, DMA analyses) and crosslink density of SMEPs are reduced, shape recovery rate is increased, while tensile strength, elongation at break and impact strength are improved. Further, shape memory epoxy syntactic foams (SMEFs) with high‐temperature adhesion are developed by introducing polymer microspheres into SMEPs. The SMEFs have compression ratio of 52–58%, and expansion ratio of 100% by adding 2% wt. microspheres. They retain the Tg and thermal stability of SMEPs, and show a delayed, slower recovery than SMEPs. Long fracture plugging experiments exhibit that a pressure‐bearing capability of 8.99–9.81 MPa is achieved with SMEFs in sealing fracture slots at a high temperature.

Polymer microsphere integrated with fiber Bragg grating for simultaneous monitoring of relative humidity and temperature

Relative humidity monitoring, usually accompanied by temperature perturbation, is an of great research field because of its various applications in the agricultural and industrial fields, and environmental monitoring. In this paper, we skillfully design and fabricate a compact fiber-optic sensor containing of fiber Bragg grating (FBG) and polymer microsphere to monitor humidity and temperature at the same time. Polymer microsphere demonstrates excellent advantages, including good thermal-humidity effect of polymeric adhesive, and the excitation of a large amount of scattered light and whispering-gallery modes in the microsphere to strongly enhance multi-mode interference and fiber-optic sensitivity. Thus, humidity sensitivity of 69.2 pm/%RH and temperature sensitivity of −110.2 pm/oC are achieved based on the polymer microsphere. FBG, another integrated structure, shows temperature sensitivity of 10.6 pm/oC and no response on ambient humidity, which could be utilized as a compensating component to extract humidity information, finally achieving simultaneous monitoring of humidity and temperature.

Aqueous remote loading of model cationic peptides in uncapped poly(lactide-co-glycolide) microspheres for long-term controlled release.

Remote loading microencapsulation of peptides into polymer microspheres without organic solvent represents a promising alternative to develop long-acting release depots relative to conventional encapsulation methods. Here, we formulated drug-free microspheres from two kinds of uncapped poly(lactide-co-glycolides) (PLGAs), i.e., ring-opening polymerized Expansorb® DLG 50-2A (50/50, 11.2kDa) and Expansorb® DLG 75-2A (75/25, 9.0kDa), and evaluated their potential capacity to remote-load and control the release of two model peptides, leuprolide and octreotide. Degradation and erosion kinetics, release mechanism, and storage stability was also assessed. As control formulations, peptide was loaded in the same PLGA 75/25 polymer by the conventional double emulsion-solvent evaporation method (W/O/W) and remote loaded in polycondensation poly(lactic-co-glycolic acid) 75/25 (Wako 7515, 14.3kDa). Loading content of 6.7%-8.9% w/w (~ 67%-89% encapsulation efficiency (EE)) was attained for octreotide, and that of 9.5% w/w loading (~ 95% EE) was observed for leuprolide, by the remote loading paradigm. Octreotide and leuprolide were both slowly and continuously released in vitro from the remote-loaded Expansorb® DLG 75-2A MPs for over 56days, which was highly similar to that observed from traditionally-loaded formulations by W/O/W (8.8% loading, 52.8% EE). The faster release kinetics was observed for the faster degrading PLGA 50/50 remote-loaded Expansorb® DLG 50-2A MPs relative to microspheres from the PLGA 75/25 Expansorb® DLG 75-2A. Despite slight differences in degradation kinetics, the release mechanism of octreotide from the Expansorb® microspheres, whether remote loaded or by W/O/W, was identical as determined by release vs. mass loss curves. Octreotide acylation was also minimal (< ~ 10%) for this polymer. Finally, drug-free Expansorb® DLG 75-2A MPs displayed excellent storage stability over 3months. Overall, this work offers support for the use of ring-opening Expansorb® PLGA-based microspheres to remote load peptides to create simple and effective long-acting release depots.

Impact of de‐icing salts on freeze‐thaw resistance of low‐clinker concretes

AbstractDe‐icing salts are commonly used in moderate climate zone, where concrete is subjected to freeze‐thaw cycles during winter times. The presence of de‐icing salts requires appropriate frost‐thaw resistance of concrete, which is challengingin case of low‐clinker concretes. Proper air‐entrainment of the concrete mix, which is one of the main factors affecting the frost resistance of concrete is not a simple task. Therefore, it is necessary to constantly improve the process of air‐entrainment of the concrete mix and to constantly control the effectiveness and quality of concrete aeration especially those with low clinker cements. In the paper effect of de‐icing salts on air‐entrained by polymer microspheres and traditional air‐entraining admixtures low clinker concrete was evaluated. The conducted tests indicate that low‐clinker concretes made with the use of polymer microspheres, despite greater repeatability in shaping the correct air‐entrainment structure, are characterized by lower resistance to frost in the presence of de‐icing salts compared to traditionally air‐entrained concretes. This mechanism will be investigated in future work.

Freeze‐thaw resistance of concretes with low‐clinker cements

AbstractThe effective use of low‐clinker cements in concrete applied in a climate with freeze‐thaw cycles is a major challenge in terms of frost durability. One of the main factors affecting the frost resistance of concrete is proper air entrainment. The use of new cement types requires constant improvement of the process of air entrainment of the concrete mix, because the application of new components to their composition significantly affect the effect of air‐entraining admixtures. This forces constant control of the effectiveness of concrete air entrainment.The article compares the possibilities of shaping the frost resistance of low‐clinker concretes with the use of polymer microspheres and traditional air‐entraining admixtures. In the tests ternary low‐clinker cements (≤ 65% of Portland clinker) made with non‐clinker main components such as silica fly ash (V), ground granulated blast furnace slag (S) and limestone (LL) were used.On the basis of the conducted tests, it was found that polymer microspheres ensure greater repeatability in shaping the correct air‐entrainment structure of low‐clinker concretes compared to traditional air‐entraining admixtures and cause a smaller decrease in compressive strength, while ensuring a high degree of frost resistance in water.

Review on Microspheres: A Novel Approach in Drug Delivery System

A well-designed controlled drug delivery system has the potential to address the limitations of conventional drug therapy and enhance the therapeutic effectiveness of a drug. Microspheres, which are characterized by their particle size being 1-1000 μm, are considered a novel and controlled drug delivery system. The spherical shape of microspheres contributes to their advantageous properties. This review focuses on the utilization of microspheres as a novel drug delivery system. These characteristics can be modified by altering the materials, methods, polymers, or techniques used in the production of microspheres. Microspheres are composed of natural or synthetic polymers. They are utilized in drug delivery systems to achieve prolonged or controlled drug release, enhancing bioavailability, stability, and action at specific sites at predetermined rates. Microspheres can be manufactured using various natural or synthetic materials. Different types of microspheres include bio adhesive, magnetic, floating, radioactive, polymeric, biodegradable polymeric, and synthetic polymeric microspheres. These microspheres are prepared using methods such as spray drying, solvent evaporation, single emulsion technique, double emulsion technique, phase separation coacervation technique, spray drying and spray congealing, solvent extraction, and quasi-emulsion solvent diffusion. Microspheres have a wide range of applications and evaluation parameters. Keywords: Microsphere, Novel Drug Delivery, Types of Microspheres, Methods of preparation Microspheres, Biodegradable.

Oxygen Delivery Biomaterials in Wound Healing Applications.

Oxygen (O2 ) delivery biomaterials have attracted great interest in the treatment of chronic wounds due to their potential applications in local and continuous O2 generation and delivery, improving cell viability until vascularization occurs, promoting structural growth of new blood vessels, simulating collagen synthesis, killing bacteria and reducing hypoxia-induced tissue damage. Therefore, different types of O2 delivery biomaterials including thin polymer films, fibers, hydrogels, or nanocomposite hydrogels have been developed to provide controlled, sufficient and long-lasting O2 to prevent hypoxia and maintain cell viability until the engineered tissue is vascularized by the host system. These biomaterials are made by various approaches, such as encapsulating O2 releasing molecules into hydrogels, polymer microspheres and 3D printed hydrogel scaffolds and adsorbing O2 carrying reagents into polymer films of fibers. In this article, different O2 generating sources such as solid inorganic peroxides, liquid peroxides, and photosynthetic microalgae, and O2 carrying perfluorocarbons and hemoglobin are presented and the applications of O2 delivery biomaterials in promoting wound healing are discussed. Furthermore, challenges encountered and future perspectives are highlighted.

High-performance electromagnetic wave absorption of nitrogen carbon doped composite materials with vanadium based nanowire structure at 2–18 GHz

With the popularization of electronic devices, the interference of electromagnetic waves on people is more and more serious, and the development of excellent EMWA materials has become increasingly urgent. In this paper, carbon and nitrogen-loaded wheat ear shaped nanocomposites (V2O3/Zn)@C were prepared by in-situ polymerization and high-temperature calcination using ZnVO nanowires as the substrate and divinylbenzene and acrylonitrile as the loading materials. The polymeric carbon microspheres were infiltrated into the ZnVO nanowires after high-temperature carbonization, forming a wheat ear shape core-shell structure. The EMWA performance of (V2O3/Zn)@C composites was optimized by adjusting the ratio between the loaded feedstock and ZnVO nanowires. The EMWA results show that (V2O3/Zn)@C exhibits excellent EMWA performance at low thickness, with an RLmin of −56.5 dB and a EABmax of 5.25 GHz. This paper provides new insights into advanced electromagnetic wave absorbing materials through special structural designs.

Mitigation of arsenic and fluoride from water via porous polymeric network knitted with zirconium moiety in three-dimensional shape: Experimental and mathematical modeling investigation

The presence of toxic contaminants in water seriously threatens human health. Thus, in order to address the water pollution through toxic contaminants, a new type of cross-linked porous polymeric microsphere namely; poly(Zirconyl dimethacrylate) (pZrDMA), was successfully prepared by a single-step facile approach. The pZrDMA comprises an acrylate chain of zirconium moiety, which is a proficient adsorbent for arsenic and fluoride remediation. A series of pZrDMA were prepared by varying the relative amounts of reactants to get an appropriate composition. The pZrDMA having, a high surface area (SA: 392.12 m2 g−1) and porosity (Pore size: 0.93–2.36 µm), has exhibited maximum adsorption capacities (qe) of 4.26 mg g−1, 4.22 mg g−1 and 198.5 mg g−1 As(V), As(III) and F− respectively. The pZrDMA displayed high removal efficiency (>97 %) for all the ions over a wide pH range (2.0 ± 0.2 to 10 ± 0.2). The adsorption kinetic and isotherms are well described by the pseudo-second-order model (PSO), and Langmuir isotherm model for both toxic ions arsenic and fluoride. The multicomponent adsorption isotherm with arsenic and fluoride has also studied. The experimental data analysis using the ANN model provides a high accuracy of the model with larger correlation coefficient values (R > 0.99). The pore diffusion modeling predicted the breakthrough time of 174 h, 1542 h, and 1466 h for F−, As(V), and As (III), respectively.

Solvothermal Synthesis and Pyrolysis Toward Heteroatom-Doped Carbon Microspheres for Zinc-Ion Hybrid Capacitors.

Heteroatom-doped porous carbon materials have investigated to promote the energy density of zinc-ion hybrid capacitors (ZICs). Yet, the quest for high-performance carbon materials or cathodes brings to light the question of which dopants facilitate fast energy storage kinetics and various types of pseudocapacitive reactions. Investigation of carbon materials with precise quantitative dopants as the key variable represents an effective appropriate approach to comprehending the intricate role of dopants in energy storage areas. Here, a straightforward solvothermal strategy is demonstrated for a variety of pristine and iron-incorporated polymer microspheres, used as precursors for durable spherical carbons intended for cathode applications in ZICs. The strategy effectively governs the incorporation of dopants within the carbon materials, whilewhile maintaining consistent morphology, microtexture, and pore structure across different carbon variations. The synergistic effect of various dopants enhance the pseudocapacitance and facilitate the ion storage process. In consequence, the optimal cathode delivers considerable capacity (178.8mAhg-1 at 0.5Ag-1), good energy density (120.2Whkg-1 at 336Wkg-1), and excellent cycling stability (101.5% capacity retention at 35000 cycles). The demonstration showcases a viable method for crafting carbon materials with precise dopants to accommodate the zinc anode, thus enabling high-capacity and high-energy ZICs.

High-Performance Fluorescent Microspheres Based on Fluorescence Resonance Energy Transfer Mode for Lateral Flow Immunoassays.

The label with a large Stokes shift and strong fluorescence properties could improve the sensitivity of the lateral flow immunoassay (LFIA). Herein, two aggregation-induced emission (AIE) luminogens with spectral overlap were encapsulated in polymers by using the microemulsion method as a label, and the construction of a fluorescence resonance energy transfer mode was further verified via theoretical calculation and spectral analysis. Satisfactorily, the doped AIE polymer microspheres (DAIEPMs) exhibited a large Stokes shift of 285 nm and a 10.8-fold fluorescence enhancement compared to those of the AIEPMs loaded with acceptors. Benefiting from the excellent optical performance, DAIEPMs were applied to the LFIA for sensitive detection of chlorothalonil, which is an organochlorine pesticide. The limit of detection of the proposed DAIEPMs-LFIA was 1.2 pg/mL, which was 4.8-fold and 11.6-fold lower than those of quantum dot bead LFIA and gold nanoparticle LFIA, respectively. This work provides a new strategy to improve the optical properties of fluorescent materials and construct a sensitive and reliable detection platform.

Boronate affinity-based surface molecularly imprinted polymer microspheres using polyethyleneimine/dopamine coating for efficient selective recognition and separation of Ginsenoside Rb1

A novel approach combining boronate affinity with surface molecular imprinting was developed for the specific recognition and separation of ginsenoside Rb1. Firstly, the boronic acid-functionalized polymer microspheres were prepared as inner cores via suspension polymerization using methyl methacrylate, ethyleneglycol dimethacrylate, and 4-vinylphenyl boronic pinacol ester (4-VBPE) as polymerization monomers. Then, the Ginsenoside Rb1 (GRb1) template was covalently pre-anchored onto the surface of microspheres through boronate affinity binding after the hydrolysis of 4-VBPE. Finally, dopamine and polyethyleneimine were used as co-coating monomers to form a thickness-controllable imprinting layer onto the polymer microspheres via in-water self-copolymerization. The key factors affecting specific recognition, including the boronic acid content, adsorption media, and polymerization time were carefully optimized. The resulting molecularly imprinted microspheres (MIMs) exhibited strong surface hydrophilicity. In the aqueous media, the optimal adsorption capacity for the template reached 81.45 μmol g−1, and the imprinting factor was 5.32. The specific evaluation showed that the MIMs had a much higher selectivity for GRb1 than its analogues, and the selectivity coefficients were all higher than 2.4. In addition, the MIMs can be applied as adsorbents for solid-phase extraction to selectively separate ginsenosides from American ginseng extract. The eluting recovery ratios of GRb1, GRg2, and GRd reach 92.39%, 88.90%, and 92.49%, respectively.

Formulation and Evaluation of Terbinafine Hydro-chloride Loaded Microsponges Gel

Background: Microsponges are porous, polymeric microspheres employed for sustained topical treatment. They may modify the release pattern, lessen adverse effects, and improve stability. Terbinafine HCL is a fungicidal allylamine derivative with a wide range of antifungal activity. It is used to treat various skin disorders like ringworm, athlete’s foot, and jock itch. Objective: The aim of the current study focuses on the development of terbinafine HCL microsponges that will release the drug in a sustained pattern to prevent side effects and then put those microsponges into a gel. Method: The quasi-emulsion solvent diffusion method was employed to develop Microsponges by using various drug: polymer ratios. Result: The results of the FTIR spectra showed that there was an absence of interaction between Terbinafine HCL and the excipients. Based on the evaluation parameter, it was found that batch MS3 showed the highest entrapment efficiency of 86.32%. Polymer EC showed better results. Microsponges and Microsponges gel showed sustained release of drug till 8 and 10 hours, respectively. The gels were shown to be stable throughout a wide temperature range, according to the stability studies. Conclusion: It was concluded that the Microsponges release the drug in a stained manner. The production process for microsponge technology has the potential to improve patient compliance with terbinafine hydrochloride microsponge gel.

Aceclofenac loaded microspheres: Formulation and evaluation of novel preprogrammed drug delivery for the treatment of arthritis

Arthritis is a widespread joint disorder globally, the patient completely dependent on NSAIDs which are administered after a fixed interval to subside the pain. This work aims to establish a preprogrammed drug delivery system of aceclofenac with a predetermined lag time for the treatment of arthritis. This new preprogrammed formulation microsphere reduces the time-dependent dose administration as it steadily releases the drug in the blood circulation reducing side effects and increasing patient compliance. Aceclofenac (ACF) loaded polymer microspheres were prepared by a new emulsification and crosslinking method using glutaraldehyde as cross-linking agent. Microspheres were prepared in 6 batches using different polymers like sodium alginate, guar gum and chitosan, alone, as well as in combinations. The type and quantity of polymers were changed in every batch while the amount of aceclofenac was unvarying. The microspheres were then evaluated for the particle size, drug content, percentage yield, percentage entrapment efficiency and percentage drug release followed by noting the lag time. The microsphere loaded with aceclofenac were formulated and evaluated, the result showed that all the preparations showed a good lag time (2–3 ​h), but chitosan (alone) gave the highest lag time, which fulfills the aim of pre-programmed drug delivery system. Preprogrammed drug release has been achieved from the microspheres over a period of 0–7 ​h, consistent with the demand for chronotherapeutic drug delivery for the treatment of arthritis. The major signification of the preparation technique includes short processing time and the lack of exposure of the ingredients to high temperatures. Aceclofenac-loaded microspheres offer a promising avenue for arthritis treatment, ensuring sustained drug release. Their potential clinical implications include enhanced therapeutic efficacy, reduced side effects, and improved patient compliance. Future directions may involve personalized formulations, targeted delivery systems, and exploring applications beyond arthritis, expanding the scope of this innovative drug delivery approach.

Stabilization mechanism of viscoelastic polymer microspheres on N2 foam system

Foam assisted flooding for crude oil displacement has been used as a commercially viable method for gas-enhanced oil recovery (EOR) processes, due to its outstanding ability in flow rate controlling. Micron-sized particles were continuously applied as the stabilizer for foam fluids, which can adsorb at the water–gas interface to increase interfacial elasticity, as such to prevent foam film rupture during bubble collisions. Current work synthesized two viscoelastic polymer microspheres by inversing emulsion polymerization, and evaluated their effectiveness as the foam fluids additives from the aspects of particle sizer and interfacial viscoelasticity. Furthermore, the ability of polymer microspheres to stabilize foam fluids was qualitatively analyzed according to the dynamics light scattering method and microscopic inspection. When containing 0.8 % SDS + 0.4 % polymer microspheres, the N2 foam system represented the most stable status for both viscoelastic polymer microspheres. The adsorption of microspheres at foam interface significantly increased the foam film strength that prevented lamella rupture when bubbles collision during the flooding process. Moreover, the sustained release property of viscoelastic polymer microspheres helped the fluid to be gradually released from the lamella, which further decreased the thinning speed of the liquid film between bubbles and to increase the foam stability.

Preparation of poly (butylene adipate-co-butylene terephthalate) microspheres via foam-transfer and investigation of their degradation behavior

Degradable polymer microspheres hold considerable significance for their application in everyday consumer products. In this study, poly (butylene adipate-co-butylene terephthalate) (PBAT) microspheres were synthesized using an improved solvent evaporation method via foam-transfer, and their degradation behavior was subsequently comprehensively examined. Experimental outcomes revealed that optimal conditions, including a PVA concentration of 2.0 wt %, a stirring rate of 600 rpm, a polymer/solvent ratio of 1:16, and a temperature of 45°C, yielded PBAT microspheres through the foam-transfer method with an impressive yield of up to 90 wt %. The degradation of PBAT microspheres was influenced by various factors, including environmental conditions, particle size, and structure. Specifically, PBAT microspheres exhibited heightened degradation when immersed in an acidic environment, possessing smaller particle sizes and a more intricate structure. In a water environment with a pH of 4, PBAT microspheres displayed a degradation rate of 36.16 wt % over a 90-day period. Furthermore, PBAT microspheres with particle sizes ranging from 20 to 30 μm showcased a degradation rate of 49.54 wt % after a 90-day immersion in water at 25°C. Notably, microspheres characterized by substantial porosity, with a porogen to polymer ratio of 180 wt %, exhibited a remarkable degradation rate of 61.66 wt % under the same conditions. As a result, this study offers a promising solution to address the issue of microplastic pollution in everyday consumer products.

Berberine-Encapsulated Poly(lactic-co-glycolic acid)-Hydroxyapatite (PLGA/HA) Microspheres Synergistically Promote Bone Regeneration with DOPA-IGF-1 via the IGF-1R/PI3K/AKT/mTOR Pathway.

Polymer microspheres have recently shown outstanding potential for bone tissue engineering due to their large specific surface area, good porosity, injectable property, good biocompatibility, and biodegradability. Their good load-release function and surface modifiability make them useful as a carrier of drugs or growth factors for the repair of bone defects in irregularly injured or complex microenvironments, such as skull defects. In this study, berberine (BBR)-encapsulated poly(lactic-co-glycolic acid) (PLGA)/hydroxyapatite (HA) microspheres were fabricated using electrified liquid jets and a phase-separation technique, followed by modification with the 3,4-hydroxyphenalyalanine-containing recombinant insulin-like growth-factor-1 (DOPA-IGF-1). Both the BBR and the IGF-1 exhibited sustained release from the IGF-1@PLGA/HA-BBR microspheres, and the composite microspheres exhibited good biocompatibility. The results of the alkaline phosphatase (ALP) activity assays showed that the BBR and IGF-1 in the composite microspheres synergistically promoted the osteogenic differentiation of MC3T3-E1 cells. Furthermore, it was confirmed that immobilized IGF-1 enhances the mRNA expression of an osteogenic-related extracellular matrix and that BBR accelerates the mRNA expression of IGF-1-mediated osteogenic differentiation and cell mineralization. Further cellular studies demonstrate that IGF-1 could further synergistically activate the IGF-1R/PI3K/AKT/mTOR pathway using BBR, thereby enhancing IGF-1-mediated osteogenesis. Rat calvarial defect repair experiments show that IGF-1@PLGA/HA-BBR microspheres can effectively promote the complete bony connection required to cover the defect site and enhance bone defect repair. These findings suggest that IGF-1@PLGA/HA-BBR composite microspheres show a great potential for bone regeneration.