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Deferoxamine (DFO) is a water-soluble iron chelator used pharmacologically for the management of patients with transfusional iron overload. However, DFO is not cell-permeable and has a short plasma half-life, which necessitates lengthy parenteral administration with an infusion pump. We previously reported the synthesis of chitosan (CS) nanoparticles for sustained slow release of DFO. In the present study, we developed solid dispersions and nanoparticles of a carboxymethyl water-soluble chitosan derivative (CMCS) for improved DFO encapsulation and release. CS dispersions and nanoparticles with DFO have been prepared by ironical gelation using sodium triphosphate (TPP) and were examined for comparison purposes. The successful presence of DFO in CMCS polymeric dispersions and nanoparticles was confirmed through FTIR measurements. Furthermore, the formation of CMCS nanoparticles led to inclusion of DFO in an amorphous state, while dispersion of DFO in the polymeric matrix led to a decrease in its crystallinity according to X-ray diffraction (XRD) and differential scanning calorimetry (DSC) results. An in vitro release assay indicated sustained release of DFO from CS and CMCS nanoparticles over 48 h and 24 h, respectively. Application of CMCS-DFO dispersions to murine RAW 264.7 macrophages or human HeLa cervical carcinoma cells triggered cellular responses to iron deficiency. These were exemplified in the induction of the mRNA encoding transferrin receptor 1, the major iron uptake protein, and the suppression of ferritin, the iron storage protein. Our data indicate that CMCS-DFO nanoparticles release bioactive DFO that causes effective iron chelation in cultured cells.
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Quitosana , Humanos , Animais , Camundongos , Desferroxamina/farmacologia , Quelantes , Transporte Biológico , FerroRESUMO
Two series of newly synthesized sustainable block copolymers based on poly(butylene succinate) (PBSu) and polylactide (PLA) were studied. The copolymers were synthesized by a ring-opening polymerization of PLA in the presence of two initial PBSu of low molar mass. We focused on the effects of the PBSu/PLA ratio (1/99 up to 15/85), chain length and initial PBSu length on the final thermal transitions in the copolymers with an emphasis on molecular mobility/dynamics and subsequently on crystallization. Both aspects are considered relevant to the final materials performance, as well as facilitation of polymer renewability. Calorimetry and dielectric spectroscopy were the main investigation tools. In the amorphous state (i.e., in which the direct effects of copolymer structure are assessable), the segmental mobility of neat PLA was significantly faster in the copolymers. Segmental mobility was monitored via the decrease in the calorimetric and dielectric (α relaxation) glass-transition temperatures, Tg and Tg,diel, respectively. The effect was systematic with an increase in the PBSu/PLA ratio, and was rationalized through the plasticizing role of PBSu (low-Tg component) and facilitated also by the simultaneous lowering of the chain length in the copolymers. Dielectric spectroscopy allowed evaluation of the dynamical fragility (cooperativity) of chains, which was strongly suppressed in the copolymers. This finding suggested an increase in free volume or a gradual increase of interchain distances. This phenomenon could favor the natural enzymatic degradation of the systems (compostability), which is limited in neat PLA. We recorded enhancement of nucleation and the crystalline fraction in the copolymers that was likely connected with faster chain diffusion. Further lowering of the Tg with the implementation of crystallization was noted (which seemed a controversial effect) but which indicated crystallization-induced phase separation.
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Chitosan is a polysaccharide vastly examined in polymer science for its unique structure. In the present study, CS was derivatized with 2-methoxy-4vinylphenol (MVP) in four different ratios through a free radical reaction. The CS-MVP derivatives were characterized through FTIR, 1H-NMR, XRD, swelling, and solubility measurements. Owing to the enhanced antioxidant character of the MVP monomer, the antioxidant activity of the CS-MVP derivatives was assessed. In the optimum CS-MVP ratio, blends between CS and CS-MVP were prepared in ratios of 90:10, 80:20, 70:30, 60:40, 50:50, 40:60, 30:70, 20:80, and 10:90 w/w, and their miscibility was examined by scanning electron microscopy (SEM) and viscosity measurements. In the optimum ratios, highly concentrated inks were prepared, and their viscosity measurements revealed the successful formation of highly viscous gels with shear thinning behavior. These inks could be appropriate candidates for biomedical and drug delivery applications.
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Quitosana , Quitosana/química , Antioxidantes/farmacologia , Polímeros/química , Sistemas de Liberação de Medicamentos , Impressão Tridimensional , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
Synthetic polymers have been an integral part of modern society since the early 1960s. Besides their most well-known applications to the public, such as packaging, construction, textiles and electronics, synthetic polymers have also revolutionized the field of medicine. Starting with the first plastic syringe developed in 1955 to the complex polymeric materials used in the regeneration of tissues, their contributions have never been more prominent. Decades of research on polymeric materials, stem cells, and three-dimensional printing contributed to the rapid progress of tissue engineering and regenerative medicine that envisages the potential future of organ transplantations. This perspective discusses the role of synthetic polymers in tissue engineering, their design and properties in relation to each type of application. Additionally, selected recent achievements of tissue engineering using synthetic polymers are outlined to provide insight into how they will contribute to the advancement of the field in the near future. In this way, we aim to provide a guide that will help scientists with synthetic polymer design and selection for different tissue engineering applications.
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Materiais Biocompatíveis , Engenharia Tecidual , Polímeros , Impressão Tridimensional , Medicina Regenerativa , Engenharia Tecidual/métodos , Alicerces TeciduaisRESUMO
A series of novel block copolymers based on two biodegradable polymers, poly(ε-caprolactone), PCL, and poly(isosorbide), PIS, with PIS fractions 5, 10, and 25 wt%, are studied herein. The aim is to assess the effects of the amorphous PIS phase on the properties of the semicrystalline PCL (majority), in addition to the synthesis strategy. The latter involved the polymerization of caprolactone onto initial PIS of low molar mass, resulting, thus, in gradually shorter PCL blocks when the starting amount of PIS is increased. The structure-property relationship investigation, with an emphasis on molecular mobility and crystallization, involves the following sum of complementary techniques: differential scanning calorimetry, dielectric spectroscopy, polarized optical microscopy and X-ray diffraction. The molecular mobility map for these PCL/PIS and initial PIS is drawn here for the first time. Despite the high glass transition temperature of PIS (Tg â¼ 51 °C) compared to that of PCL (-66 °C), the Tg of the copolymers barely changes, as it is mainly ruled by crystallinity. The latter seems to be facilitated in the copolymers, in both the amount and the rate. The local molecular mobility of PCL and PCL/PIS consists of faster γPCL relaxation which is unaffected in the copolymers, whereas the slower ßPCL process arising from the backbone ester group rotation exhibits a systematic deceleration in the presence of PIS. A connection between such local motions and the corresponding segmental α relaxation, observed previously in other polyesters, is also found to be true here. Apart from that, the dielectric Tg as well as the cooperativity of the polymer chains drop moderately, which indicates spatial confinement between the PCL crystals, whereas correlations with the looser lamellar chain packing within the spherulites are gained. The relaxations of initial PIS, i.e., γPIS, ßPIS and αPIS, could not be resolved within the copolymers. Along with other properties, such as ionic conductivity, we conclude to the homogeneity of our systems, with sufficient PCL/PIS distribution.
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Poliésteres , Polímeros , Cristalização , Poliésteres/química , Polímeros/químicaRESUMO
In this work, we study a series of sustainable block copolymers based on polylactide, PLA, and poly(propylene adipate), PPAd, both polymers being prepared from renewable resources. Envisaging a wide range of future applications in the frame of a green and circular economy, e.g., packaging materials replacing conventional petrochemicals, the employment of PPAd aims at lowering the glass transition and melting temperatures of PLA and, finally, facilitation of the enzymatic degradation and compostability. The copolymers have been synthesized via ring opening polymerization of lactides in the presence of propylene adipate oligomers (5, 15 and 25%). The direct effects on the molecular mobility by the structure/composition are assessed in the amorphous state employing broadband dielectric spectroscopy (BDS) and calorimetry. BDS allowed the recording of local PLA and PPAd dynamics in all cases. The effects on local relaxations suggest favoring of interchain interactions, both PLA-PPAd and PPAd-PPAd. Regarding the more important segmental dynamics, the presence of PPAd leads to faster polymer chain diffusion, as monitored by the significant lowering of the dielectric and calorimetric glass transition temperature, Tg. This suggests the plasticizing role of PPAd on PLA (majority) in combination with the lowering of the average molar mass, Mn, in the copolymers from â¼75 to â¼30 kg mol-1, which is the actual scope for the synthesis of these materials. Interestingly, a strong suppression in fragility (chain cooperativity) is additionally recorded. In contrast to calorimetry and due to the high resolving power of BDS, for the higher PPAd fraction, the weak segmental relaxation of PPAd was additionally recorded. Overall, the recordings suggest a strong increase in free volume and two individual dynamic states, one for 0 and 5% PPAd and another for 15 and 25% PPAd. Within the latter, we gained indications for partial phase nano-separation of PPAd. Regarding indirect effects, these were followed via crystallization. Independent of the method of crystallization, namely, melt or cold, the presence of PPAd led to the systematic lowering of crystallization and melting temperatures and enthalpies. The effects reflect the decrease of crystalline nuclei, which is confirmed by optical microscopy as in the copolymers fewer although larger crystals are formed.
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This work deals with molecular mobility in renewable block copolymers based on polylactide (PLA) and poly(propylene adipate) (PPAd). In particular, we assess non-trivial effects on the mobility arising from the implementation of crystallization. Differential scanning calorimetry, polarized light microscopy and broadband dielectric spectroscopy were employed in combination for this study. The materials were subjected to various thermal treatments aiming at the manipulation of crystallization, namely, fast and slow cooling, isothermal melt- and cold-crystallization. Subsequently, we evaluated the changes recorded in the overall thermal behavior, semicrystalline morphology and molecular mobility (segmental and local). The molecular dynamics map for neat PPAd is presented here for the first time. Unexpectedly, the glass transition temperature, Tg, in the amorphous state drops upon crystallization by 8-50 K. The drop becomes stronger with the increase in the PPAd fraction. Compared to the amorphous state, crystallization leads to significantly faster segmental dynamics with severely suppressed cooperativity. For the PLA/PPAd copolymers, the effects are systematically stronger in the cold- as compared to the melt-crystallization, whereas the opposite happens for neat PLA. The local ßPLA relaxation of PLA was, interestingly, recorded to almost vanish upon crystallization. This suggests that the corresponding molecular groups (carbonyl) are strongly involved and immobilized within the semicrystalline regions. The overall results suggest the involvement of either spatial nanoconfinement imposed on the mobile chains within the inter-crystal amorphous areas and/or a crystallization-driven effect of nanophase separation. The latter phase separation seems to be at the origins of the significant discrepancy recorded between the calorimetric and dielectric recordings on Tg in the copolymers. Once again, compared to more conventional techniques such as calorimetry, dielectric spectroscopy was proved a powerful and quite sensitive tool in recording such effects as well as in providing indirect indications for the polymer chains' topology.
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Poliésteres , Temperatura de Transição , Cristalização/métodosRESUMO
This work describes the synthesis of poly(butylene adipate) (PBAd), by melt polycondensation, poly(l-lactic acid) (PLLA), by ring opening polymerization, and the new block copolymer PLLA/PBAd in ratios 90/10, 95/5, 75/25 and 50/50. Due to the biocompatibility and low toxicity of neat PBAd and PLLA, these copolymers are suitable to be used in biomedical applications. The 1H and 13C nuclear magnetic resonance spectroscopy techniques were employed for structural characterization. The thermal transitions, with an emphasis on crystallization, were assessed by differential scanning calorimetry, supplemented by X-ray diffraction and polarized optical microscopy. Molecular mobility studies were conducted using two advanced techniques, broadband dielectric spectroscopy and thermally stimulated depolarization currents. The results from the structural techniques, in combination with each other, provided proof of the presence of PLLA and PBAd blocks and, moreover, the successful copolymer synthesis. The overall data showed that the different co-polymer compositions result directly in severe changes in the polymer crystal distribution and, indirectly, the formation of PBAd micro/nano domains surrounded by PLLA. Furthermore, it was demonstrated that both the continuity of the two polymers throughout the copolymer volume and the semicrystalline morphology can be tuned to a wide extent. The latter makes these systems quite promising envisaging biomedical applications, including the encapsulation of small molecules, e.g. drug solutions. The molecular mobility map was constructed for these systems for the first time, revealing the local (short scale) and segmental (larger nm scale) mobility of PBAd and PLLA, as well as intermediate behaviors of the copolymers.
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Poliésteres , Polímeros , Butileno Glicóis , Ácido Láctico , Difração de Raios XRESUMO
In this work, we synthesized poly(ε-caprolactone) (PCL) and three copolyesters of different architectures based on three different alcohols, namely a three arm-copolymer based on 1% glycerol (PCL_Gly), a four arm-copolymer based on 1% pentaerythrytol (PCL_PE), and a linear block copolymer based on â¼50% methoxy-poly(ethylene glycol) (PCL_mPEG), all simultaneously with the ring opening polymerization (ROP) of PCL. Due to their biocompatibility and low toxicity, these systems are envisaged for use in drug delivery and tissue engineering applications. Due to the in situ ROP during the copolyesters synthesis, the molecular weight of PCL, Wm initially â¼62 kg mol-1, drops in the copolymers from â¼60k down to â¼5k. For the structure-properties investigation we employed differential scanning calorimetry (DSC and TMDSC), X-ray diffraction (XRD), nuclear magnetic resonance (NMR), Fourier transform infra red (FTIR) spectroscopy, polarized optical microscopy (POM), broadband dielectric spectroscopy (BDS) and isothermal water sorption. DSC revealed that the crystalline fraction of PCL increases whereas the crystallization rate drops in the copolymers in the order PCL â¼ PCL_Gly > PCL_PE â« PCL_mPEG, which coincides with that of decreasing Wm. In PCL_mPEG the major amount of PCL (87%) was found to crystallize while the majority of mPEG (92%) was found amorphous exhibiting constrained amorphous mobility and severely slower/weaker crystallization as compared to neat mPEG. Segmental dynamics in BDS, in agreement with DSC, is similar and in general slow for the samples of star-like structure for Wm ≥ 30k arising from PCL, whereas it is severely faster and enhanced in strength for the linear PCL_mPEG (lower Wm) copolymer arising from mPEG. For the latter system, the data provide indications for the formation of complex structures consisting of many small PCL crystallites surrounded by amorphous mPEG segments with constrained dynamics and severely suppressed hydrophilicity. These effects cannot be easily assessed by conventional XRD and POM, confirming the power of the dielectric technique. The overall recordings indicated that the different polymer architecture results in severe changes in the semicrystalline morphology, which demonstrates the potential for tuning the final product performance (permeability, mechanical).
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Espectroscopia Dielétrica , Poliésteres , Varredura Diferencial de Calorimetria , Cristalização , PolietilenoglicóisRESUMO
The utilization of polymer/metal organic framework (MOF) nanocomposites in various biomedical applications has been widely studied due to their unique properties that arise from MOFs or hybrid composite systems. This review focuses on the types of polymer/MOF nanocomposites used in drug delivery and imaging applications. Initially, a comprehensive introduction to the synthesis and structure of MOFs and bio-MOFs is presented. Subsequently, the properties and the performance of polymer/MOF nanocomposites used in these applications are examined, in relation to the approach applied for their synthesis: (i) non-covalent attachment, (ii) covalent attachment, (iii) polymer coordination to metal ions, (iv) MOF encapsulation in polymers, and (v) other strategies. A critical comparison and discussion of the effectiveness of polymer/MOF nanocomposites regarding their synthesis methods and their structural characteristics is presented.
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Estruturas Metalorgânicas/química , Estruturas Metalorgânicas/síntese química , Metais/química , Nanocompostos/química , Polímeros/química , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Sistemas de Liberação de Medicamentos , Ligação de Hidrogênio , Imageamento por Ressonância Magnética , Estruturas Metalorgânicas/farmacologia , Metais/metabolismo , Metais/farmacologia , Nanocompostos/uso terapêutico , Polimerização , Eletricidade EstáticaRESUMO
Chitosan (CS) is a natural polysaccharide, widely studied in the past due to its unique properties such as biocompatibility, biodegradability and non-toxicity. Chemical modification of CS is an effective pathway to prepare new matrices with additional functional groups and improved properties, such as increment of hydrophilicity and swelling rate, for drug delivery purposes. In the present study, four derivatives of CS with trans-aconitic acid (t-Acon), succinic anhydride (Succ), 2-hydroxyethyl acrylate (2-HEA) and acrylic acid (AA) were prepared, and their successful grafting was confirmed by FTIR and 1H-NMR spectroscopies. Neat chitosan and its grafted derivatives were fabricated for the encapsulation of fluticasone propionate (FLU) and salmeterol xinafoate (SX) drugs, used for chronic obstructive pulmonary disease (COPD), via the ionotropic gelation technique. Scanning electron microscopy (SEM) micrographs demonstrated that round-shaped microparticles (MPs) were effectively prepared with average sizes ranging between 0.4 and 2.2 µm, as were measured by dynamic light scattering (DLS), while zeta potential verified in all cases their positive charged surface. FTIR spectroscopy showed that some interactions take place between the drugs and the polymeric matrices, while X-ray diffraction (XRD) patterns exhibited that both drugs were encapsulated in MPs' interior with a lower degree of crystallinity than the neat drugs. In vitro release studies of FLU and SX exposed a great amelioration in the drugs' dissolution profile from all modified CS's MPs, in comparison to those of neat drugs. The latter fact is attributed to the reduction in crystallinity of the active substances in the MPs' interior.
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Fluticasona , Xinafoato de Salmeterol , Administração por Inalação , Cápsulas , Preparações de Ação Retardada/química , Preparações de Ação Retardada/farmacocinética , Preparações de Ação Retardada/farmacologia , Fluticasona/química , Fluticasona/farmacocinética , Fluticasona/farmacologia , Humanos , Tamanho da Partícula , Doença Pulmonar Obstrutiva Crônica/tratamento farmacológico , Doença Pulmonar Obstrutiva Crônica/metabolismo , Xinafoato de Salmeterol/química , Xinafoato de Salmeterol/farmacocinética , Xinafoato de Salmeterol/farmacologiaRESUMO
In a century when environmental pollution is a major issue, polymers issued from bio-based monomers have gained important interest, as they are expected to be environment-friendly, and biocompatible, with non-toxic degradation products. In parallel, hyperbranched polymers have emerged as an easily accessible alternative to dendrimers with numerous potential applications. Glycerol (Gly) is a natural, low-cost, trifunctional monomer, with a production expected to grow significantly, and thus an excellent candidate for the synthesis of hyperbranched polyesters for pharmaceutical and biomedical applications. In the present article, we review the synthesis, properties, and applications of glycerol polyesters of aliphatic dicarboxylic acids (from succinic to sebacic acids) as well as the copolymers of glycerol or hyperbranched polyglycerol with poly(lactic acid) and poly(ε-caprolactone). Emphasis was given to summarize the synthetic procedures (monomer molar ratio, used catalysts, temperatures, etc.,) and their effect on the molecular weight, solubility, and thermal and mechanical properties of the prepared hyperbranched polymers. Their applications in pharmaceutical technology as drug carries and in biomedical applications focusing on regenerative medicine are highlighted.
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Materiais Biocompatíveis , Dendrímeros , Portadores de Fármacos , Glicerol , Poliésteres , Polímeros , Materiais Biocompatíveis/síntese química , Materiais Biocompatíveis/química , Materiais Biocompatíveis/uso terapêutico , Dendrímeros/síntese química , Dendrímeros/química , Dendrímeros/uso terapêutico , Portadores de Fármacos/síntese química , Portadores de Fármacos/química , Portadores de Fármacos/uso terapêutico , Glicerol/síntese química , Glicerol/química , Glicerol/uso terapêutico , Humanos , Poliésteres/síntese química , Poliésteres/química , Poliésteres/uso terapêutico , Polímeros/síntese química , Polímeros/química , Polímeros/uso terapêutico , Medicina RegenerativaRESUMO
The attraction of nucleic acids to lipidic compartments is the first step for carriers of potentially inheritable information to self-organise in functionalised synthetic cells. Confocal fluorescence imaging shows that a synthetic amphiphilic peptidyl RNA molecule spontaneously accumulates at the outer bilayer membranes of phospho- and glycolipidic giant vesicles. Cooperatively attractive interactions of -3.4 to -4.0 kcal mol(-1) between a random coil hydrophobic peptide and lipid membranes can thus pilot lipophobic RNA to its compartmentation. The separation of mixed lipid phases in the membranes further enhances the local concentration of anchored RNA.
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Bicamadas Lipídicas/química , Peptídeos/química , RNA/química , Interações Hidrofóbicas e Hidrofílicas , Lipídeos de Membrana/química , Peptídeos/síntese química , Tensoativos/síntese química , Tensoativos/químicaRESUMO
A series of novel renewable copolymers based on poly(ethylene succinate) (PESu) and poly(isosorbide succinate) (PISSu), with the Isosorbide (Is)/PESu molar ratio varying from 5/95 to 75/25, were synthesized in-situ and studied in this work. A sum of characterization techniques was employed here for the structural and thermo-dynamical characterization. The sophisticated technique of dielectric spectroscopy, along with proper analysis, enabled the molecular dynamics mapping of both the local and segmental types, which is presented for such materials for the first time. With increasing the Is fraction, shorter copolymeric entities were gradually formed. Based on the overall findings, the systems were found to be homogeneous, e.g., exhibiting single glass transitions, with the two polymer segments being found to be excellently distributed. The latter is indirect, although strong, evidence for the successful copolymerization. The thermal degradation mechanism for the copolymers was exhaustingly explored employing analytical pyrolysis. The systems exhibited, in general, good thermal stability, according to the thermogravimetric analysis. Confirming one of the initial scopes for the present systems, isosorbide plays here the role of hardener (PISSu) over the soft polymer (PESu), and this is reflected in the monotonic increase of the glass transition temperature, Tg, from -16 to ~56 °C. The introduction of Is results in an increase in constraints (hardening of the matrix), while there seems to be an overall densification of the polymer (decrease of the free volume).
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In the present work, novel interpenetrated networks (IPNs) of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide) (SBMA) and poly(vinyl alcohol) (PVA) were prepared for the ocular co-administration of timolol maleate (TIM) and dorzolamide hydrochloride (DORZ), two drugs widely used for the treatment of glaucoma. The successful polymerization of SBMA, in the presence of PVA, led to the formation of semi-interpenetrated pSBMA-PVA networks (IPNs), in the form of sponges, exhibiting intrinsic antimicrobial properties attributed to SBMA. Fourier-transform infrared spectroscopy (FTIR) was utilized to confirm the successful synthesis of the IPNs. Further assessments, including contact angle and water sorption measurements, highlighted their significant hydrophilicity, a feature that makes them suitable for ocular applications. Differential scanning calorimetry (DSC) measurements indicated that PVA serves as a plasticizer, while an assessment of the water sorption capacity of these materials suggested that although the incorporation of PVA results in slightly less hydrophilic materials, the prepared sponges still remain sufficiently hydrophilic for ocular use. Following their characterization, the optimal pSBMA-PVA IPN was used to encapsulate TIM and DORZ. Irritation tests, performed using the HET-CAM method, confirmed that the drug-loaded sponges were safe and potentially well-tolerated for ophthalmic use. Finally, the co-release study for the two drugs revealed a sustained release pattern in both cases, while drug release from the sponges was primarily controlled by diffusion.
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This work aimed to produce bio-based poly(ethylene furanoate) (PEF) with a high molecular weight using 2,5-furan dicarboxylic acid (FDCA) or its derivative dimethyl 2,5-furan dicarboxylate (DMFD), targeting food packaging applications. The effect of monomer type, molar ratios, catalyst, polycondensation time, and temperature on synthesized samples' intrinsic viscosities and color intensity was evaluated. It was found that FDCA is more effective than DMFD in producing PEF with higher molecular weight. A sum of complementary techniques was employed to study the structure-properties relationships of the prepared PEF samples, both in amorphous and semicrystalline states. The amorphous samples exhibited an increase in glass transition temperature of 82-87 °C, and annealed samples displayed a decrease in crystallinity with increasing intrinsic viscosity, as analyzed by differential scanning calorimetry and X-ray diffraction. Dielectric spectroscopy showed moderate local and segmental dynamics and high ionic conductivity for the 2,5-FDCA-based samples. The spherulite size and nuclei density of samples improved with increased melt crystallization and viscosity, respectively. The hydrophilicity and oxygen permeability of the samples were reduced with increased rigidity and molecular weight. The nanoindentation test showed that the hardness and elastic modulus of amorphous and annealed samples is higher at low viscosities due to high intermolecular interactions and degree of crystallinity.
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3D printing, or additive manufacturing, has gained considerable interest due to its versatility regarding design as well as in the large choice of materials. It is a powerful tool in the field of personalized pharmaceutical treatment, particularly crucial for pediatric and geriatric patients. Polysaccharides are abundant and inexpensive natural polymers, that are already widely used in the food industry and as excipients in pharmaceutical and cosmetic formulations. Due to their intrinsic properties, such as biocompatibility, biodegradability, non-immunogenicity, etc., polysaccharides are largely investigated as matrices for drug delivery. Although an increasing number of interesting reviews on additive manufacturing and drug delivery are being published, there is a gap concerning the printing of polysaccharides. In this article, we will review recent advances in the 3D printing of polysaccharides focused on drug delivery applications. Among the large family of polysaccharides, the present review will particularly focus on cellulose and cellulose derivatives, chitosan and sodium alginate, printed by fused deposition modeling and extrusion-based printing.
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This research focuses on key priorities in the field of sustainable plastic composites that will lead to a reduction in CO2 pollution and support the EU's goal of becoming carbon neutral by 2050. The main challenge is to develop high-performance polyphenol-reinforced thermoplastic composites, where the use of natural fillers replaces the usual chemical additives with non-toxic ones, not only to improve the final performance but also to increase the desired multifunctionalities (structural, antioxidant, and antibacterial). Therefore, poly (lactic acid) (PLA) composites based on Kraft lignin (KL) and tannin (TANN) were investigated. Two series of PLA composites, PLA-KL and PLA-TANN, which contained natural fillers (0.5%, 1.0%, and 2.5% (w/w)) were prepared by hot melt extrusion. The effects of KL and TANN on the PLA matrices were investigated, especially the surface physicochemical properties, mechanical properties, and antioxidant/antimicrobial activity. The surface physicochemical properties were evaluated by measuring the contact angle (CA), roughness, zeta potential, and nanoindentation. The results of the water contact angle showed that neither KL nor TANN caused a significant change in the wettability, but only a slight increase in the hydrophilicity of the PLA composites. The filler loading, the size of the particles with their available functional groups on the surfaces of the PLA composites, and the interaction between the filler and the PLA polymer depend on the roughness and zeta potential behavior of the PLA-KL and PLA-TANN composites and ultimately improve the surface mechanical properties. The antioxidant properties of the PLA-KL and PLA-TANN composites were determined using the DPPH (2,2'-diphenyl-1-picrylhydrazyl) test. The results show an efficient antioxidant behavior of all PLA-KL and PLA-TANN composites, which increases with the filler content. Finally, the KL- and PLA-based TANN have shown resistance to the Gram-negative bacteria, E. coli, but without a correlation trend between polyphenol filler content and structure.
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In the present work, Risperidone microparticles from poly(lactic acid)/poly(hexylene succinate) (PLA-b-PHSu) block copolymers in different ratios, 95/05, 90/10 and 80/20 w/w, were examined as long-acting injectable formulations. Nuclear magnetic resonance (NMR) was used to verify the successful synthesis of copolymers. Enzymatic hydrolysis showed an increase in weight loss as the content of PHSu increased, while the cytotoxicity studies confirmed the biocompatibility of the copolymers. The polyesters were further used to encapsulate Risperidone by spray drying. The drug-loaded microparticles were studied by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). SEM microphotographs confirmed that spherically shaped microparticles were prepared with sizes about 5-12 µm, while XRD and differential scanning calorimetry (DSC) studies evidenced that Risperidone was encapsulated in amorphous form. The drug loading and the entrapment efficiency of Risperidone were studied as well as the in vitro release from the prepared microparticles. As the content of PHSu increased, a higher release of Risperidone was observed, with PLA-b-PHSu 80/20 w/w succeeding to release 100% of RIS within 12 days. According to theoretical modeling, the kinetics of RIS release from PLA-b-PHSu microparticles is complex, governed by both diffusion and polymer erosion.
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A series of N-methyl quaternized derivatives of poly(4-vinylpyridine) (PVP) were synthesized in high yields with different degrees of quaternization, obtained by varying the methyl iodide molar ratio and affording products with unexplored optical and solvation properties. The impact of quaternization on the physicochemical properties of the copolymers, and notably the solvation properties, was further studied. The structure of the synthesized polymers and the quaternization degrees were determined by infrared and nuclear magnetic spectroscopies, while their thermal characteristics were studied by differential scanning calorimetry and their thermal stability and degradation by thermogravimetric analysis (TG-DTA). Attention was given to their optical properties, where UV-Vis and diffuse reflectance spectroscopy (DRS) measurements were carried out. The optical band gap of the polymers was calculated and correlated with the degree of quaternization. The study was further orientated towards the solvation properties of the polymers in binary solvent mixtures that strongly depend on the degree of quaternization, enabling a better understanding of the key polymer (solute)-solvent interactions. The assessment of the underlying solvation phenomena was performed in a system of different ratios of DMSO/H2O and the solvatochromic indicator used was Reichardt's dye. Solvent polarity parameters have a significant effect on the visible spectra of the nitrogen quaternization of PVP studied in this work and a detailed path towards this assessment is presented.