PLGA Nanospheres Research Articles

The effect of the release behavior of simvastatin from different PLGA particles on bone regeneration in vitro and in vivo: Comparison of simvastatin-loaded PLGA microspheres and nanospheres

Simvastatin is a cholesterol-lowering drug known to affect bone formation in vivo and its sustainable administration into localized areas is of particular interest in the dental field. Two simvastatin-loaded poly(lactic-co-glycolic acid) (PLGA) formulations (PLGA microspheres and PLGA nanospheres) were compared to investigate whether a sustainable supply of simvastatin from a PLGA-based carrier is effective for bone regeneration. PLGA microspheres successfully presented sustained release of simvastatin for one month, whereas simvastatin was continuously released from PLGA nanospheres for one week. The difference of drug release pattern between two PLGA particles was confirmed by Korsmeyer–Peppas mathematical model. PLGA microspheres and simvastatin alone (no carrier) induced the proliferation MC3T3-E1 cells and increased alkaline phosphatase (ALP) activity, a differentiation marker of MC3T3-E1 cells, whereas PLGA nanospheres did not. These results suggested that PLGA nanospheres had an adverse effect on bone generation in vitro due to the production of PLGA metabolized products. Both PLGA microspheres and PLGA nanospheres provided a bone formation effect in an in vivo rat calvaria bone defect model and PLGA microspheres were superior to PLGA nanospheres. Our data suggest that simvastatin-loaded PLGA microspheres can release simvastatin sustainably and induce bone formation more efficiently than PLGA nanospheres, thus promoting bone regeneration.

Therapeutic Use of 3β-[N-(N',N'-Dimethylaminoethane) Carbamoyl] Cholesterol-Modified PLGA Nanospheres as Gene Delivery Vehicles for Spinal Cord Injury.

Gene delivery holds therapeutic promise for the treatment of neurological diseases and spinal cord injury. Although several studies have investigated the use of non-viral vectors, such as polyethylenimine (PEI), their clinical value is limited by their cytotoxicity. Recently, biodegradable poly (lactide-co-glycolide) (PLGA) nanospheres have been explored as non-viral vectors. Here, we show that modification of PLGA nanospheres with 3β-[N-(N′,N′-dimethylaminoethane) carbamoyl] cholesterol (DC-Chol) enhances gene transfection efficiency. PLGA/DC-Chol nanospheres encapsulating DNA were prepared using a double emulsion-solvent evaporation method. PLGA/DC-Chol nanospheres were less cytotoxic than PEI both in vitro and in vivo. DC-Chol modification improved the uptake of nanospheres, thereby increasing their transfection efficiency in mouse neural stem cells in vitro and rat spinal cord in vivo. Also, transgene expression induced by PLGA nanospheres was higher and longer-lasting than that induced by PEI. In a rat model of spinal cord injury, PLGA/DC-Chol nanospheres loaded with vascular endothelial growth factor gene increased angiogenesis at the injury site, improved tissue regeneration, and resulted in better recovery of locomotor function. These results suggest that DC-Chol-modified PLGA nanospheres could serve as therapeutic gene delivery vehicles for spinal cord injury.

3D printing biomimetic nanomaterials for highly efficient vascularized bone development

Event Abstract Back to Event 3D printing biomimetic nanomaterials for highly efficient vascularized bone development Benjamin Holmes1*, Michael Plesniak1* and Grace Zhang1, 2, 3 1 The George Washington University, Mechanical and Aerospace Engineering, United States 2 The George Washington University, Department of Biomedical Engineering, United States 3 The George Washington University, Division of Genomic Medicine, Department of Medicine, United States Introduction: Large critical sized bone defects are notoriously hard to regenerate due to the need for such large and complex portions of tissue to have an adequate vascular network. As an emerging tissue fabrication technique, 3D bioprinting offers great precision to control the internal architecture of a scaffold and print complicated structures close in architecture to biological tissue[1]. Thus, the objective of this study is to combine a microvascular 3D printed design with biomimetic nanomaterials (i.e., bone minerals, nanocrystalline hydroxyapatite (nHA) and growth factor loaded nanospheres) for highly efficient fluid perfusion and enhanced vascularized bone regeneration. Materials and Methods: Two types of scaffolds with both large (500 µm radius) and small (250 µm radius) fluid microchannels (Figure 1) were designed and 3D printed via fused deposition molding printing from biocompatible polylactic acid (PLA). Biomimetic osteogenic nHA and angiogenic vascular endothelial growth factor (VEGF) loaded PLGA nanospheres were fabricated and then conjugated onto the 3D printed scaffolds using a multi-step aminolysis process. The scaffolds were characterized via scanning electron microscopy (SEM). The VEGF release from the scaffolds was characterized for 7 days. Both human umbilical vein endothelial cell (HUVECs) and human bone marrow mesenchymal stem cell (hMSCs) functions in the 3D printed scaffolds were investigated in vitro. Figure 1; Computer aided designs (CAD) of large (left) and right (small) microvascular channel bone scaffolds. Results and Discussion: SEM showed that the conjugation of nanomaterials had a noticeable effect on the nano-topography when compared to untreated PLA. 7 day VEGF release study showed a slow release rate after 48 hours on scaffolds with VEGF encapsulated nanospheres, when compared to bare VEGF samples. In addition, the scaffolds with larger microchannels and a smaller PLGA nanosphere concentration both provide a more efficient mechanism for HUVEC cell invasion and proliferation. Figure 2 shows hMSC 3 week differentiation on scaffolds with pre-cultured HUVEC vascular networks. Figure 2; 1, 2 and 3 week calcium deposition of hMSCs cultured on scaffolds which have been pre-cultured with HUVECs for 1 week. Data are ± standard error of the mean, N=3; *p<0.05 when compared to all other groups at weeks 1 and 2, respectively; **p<0.05 when compared to scaffolds with large and small microchannels at week 1; ***p<0.05 when compared to scaffolds with small microchannels at week 3; and #p<0.05 when compared to all other groups at week 3. Excellent calcium deposition was exhibited on scaffolds with both VEGF loaded PLGA nanospheres and nHA. Yet, higher values in calcium were seen on samples with only PLGA nanospheres, when compared to plain PLA controls. A similar trend could be observed for collagen type I synthesis on scaffolds. In both cases, higher amount of bone matrix deposited can be attributed to the presence of nHA, but it can also be inferred that the presence of VEGF and HUVECs induced cell to cell interactions which also lead to faster bone tissue formation. Conclusion: Based on these results, it can be inferred that the use of a drug loaded nanoparticle delivery system, along with nHA, a bioactive conjugation method and highly efficient 3D printed micro designs for cell growth, infiltration and fluid perfusion can yield a highly effective method for the enhanced growth of vascularized bone.

Improvement of the Facial Pores Troubles with Functional Cosmetic Containing PLGA Nanospheres

Improvement of the Facial Pores Troubles with Functional Cosmetic Containing PLGA Nanospheres

Funded Research for Developing Pharmaceutical Preparations and Medical Devices with Drug Delivery System (DDS) Technology Utilizing PLGA Nanospheres

Funded Research for Developing Pharmaceutical Preparations and Medical Devices with Drug Delivery System (DDS) Technology Utilizing PLGA Nanospheres

Study of Thermal Degradation of PLGA, PLGA Nanospheres and PLGA/Maghemite Superparamagnetic Nanospheres

Poly(glycolide-co-lactide) (PLGA) nanospheres containing magnetic materials have been extensively studied because of its biomedical applications. Therefore, it is very important to know thermal properties of these materials in addition to other physical properties. Thermal degradation activation energy (Eα) of PLGA nanospheres with maghemite entrapment (PLGA-Mag), PLGA nanospheres (hollow spheres) (PLGA-H) obtained by an emulsion method and unprocessed PLGA (PLGA-R) were calculated by isoconversional Vyazovkin method based on data of TG analysis in order to evaluate modifications in thermal behavior caused by nanospheres obtainment process or by maghemite entrapment. Both hydrodynamic diameter in the range of 200-250 nm and polydispersity index lower than 0.3 are considered satisfactory. Thermal degradation of PLGA-R begins at higher temperatures than those of PLGA-H and PLGA-Mag, but processed samples presented increase in thermal stability, which was greater before processing by emulsion and in the presence of the magnetic materials. PLGA-Mag presents superparamagnetic behavior at room temperature.

Surface functionalization of polymeric nanospheres modulates macrophage activation: relevance in leishmaniasis therapy.

To characterize the production and application of carbohydrate functionalized poly(D,L-lactide-co-glycolide) (PLGA) nanospheres as immune-modulatory mediators in the treatment of visceral leishmaniasis (VL). PLGA nanospheres were prepared by nanoprecipitation and surface functionalized with mannose, mannan or mannosamine moieties using a carbodiimide reaction. Flow cytometry and fluorescence microscopy revealed the interaction of these nanospheres with macrophages. The nanocarriers were taken up by murine primary macrophages using clathrin-mediated endocytosis. Co-culture of macrophages with carbohydrate-functionalized nanospheres led to their activation and production of pro-inflammatory cytokines. One dose of amphotericin B-loaded on mannan-functionalized nanospheres resulted in an efficacy VL therapy. This approach provides a promising therapy for VL and a new therapeutic nanoplatform for obligate intracellular pathogens.

Patterned substrates fabricated by a controlled freezing approach and biocompatibility evaluation by stem cells.

Patterned substrates have been widely used in the studies investigating how to regulate cell growth and alignment. Such substrates may be fabricated by various techniques such as photolithography, soft lithography and microcontact printing. We report here a facile approach to fabricate aligned and grid surface patterns by a controlled freezing approach and further investigate their biocompatibility. The fabrication has been demonstrated with polymers (hydrophilic & hydrophobic), nanoparticles (organic & inorganic), or mixtures of these components. For the aligned surface patterns, the spacings between the patterned ridges can be tuned by varying the freezing rates. The biocompatibility of the substrates is evaluated by WST-8 viability tests with cell counting kit-8 (CCK-8) and by culturing with mouse mesenchymal stem cells (mMSCs). Three surface-patterned substrates (PLGA, PLGA nanospheres with chitosan, and silica colloids) are evaluated in more details to show that the mMSCs can grow alongside the aligned ridges while the cells grow randomly when plain glass slides are used as control. Further observations show that PLGA substrates undergo degradation, and are thus unsuitable for cell culture over the longer term. On the other hand, the PLGA-chitosan substrate and silica substrate were stable and could maintain mMSC alignment throughout the culture period.

Nanocomposite hydrogels based on embedded PLGA nanoparticles in gelatin

Novel nanocomposites based on gelatin polymer networks containing poly(lactic-co-glycolide) (PLGA) nanoparticles (PLGA-NPs) were prepared and morphological, chemical and rheological properties were investigated. The successful incorporation of PLGA nanoparticles into the gelatin gels was confirmed by field emission scanning electron microscope (FESEM) and infrared spectroscopy (FT-IR). FESEM microscopy showed also a more homogeneous pore structure of the nanocomposite with respect to the primary gel. The introduction of PLGA nanospheres at a 1% w/v with respect to gelatin weight does not influence the elastic modulus of the pristine gelatin but an increase in the amount of PLGA spheres determine a negative effect on the elastic modulus. The prepared PLGA-NPs gelatin gels with biocompatible and biodegradable properties are very interesting from both applied and fundamental perspectives for a future application in biomedical and food fields for the control release of active molecules.

Formulation, characterization and evaluation of cyclodextrin-complexed bendamustine-encapsulated PLGA nanospheres for sustained delivery in cancer treatment

PLGA nanospheres are considered to be promising drug carrier in the treatment of cancer. Inclusion complex of bendamustine (BM) with epichlorohydrin beta cyclodextrin polymer was prepared by freeze-drying method. Phase solubility study revealed formation of AL type complex with stability constant (Ks = 645 M−1). This inclusion complex was encapsulated into PLGA nanospheres using solid-in-oil-in-water (S/O/W) technique. The particle size and zeta potential of PLGA nanospheres loaded with cyclodextrin-complexed BM were about 151.4 ± 2.53 nm and − 31.9 ± (−3.08) mV. In-vitro release study represented biphasic release pattern with 20% burst effect and sustained slow release. DSC studies indicated that inclusion complex incorporated in PLGA nanospheres was not in a crystalline state but existed in an amorphous or molecular state. The cytotoxicity experiment was studied in Z-138 cells and IC50 value was found to be 4.3 ± 0.11 µM. Cell viability studies revealed that the PLGA nanospheres loaded with complex exerts a more pronounced effect on the cancer cells as compared to the free drug. In conclusion, PLGA nanospheres loaded with inclusion complex of BM led to sustained drug delivery. The nanospheres were stable after 3 months of storage conditions with slight change in their particle size, zeta potential and entrapment efficiency.

Gemcitabine loaded biodegradable PLGA nanospheres for in vitro pancreatic cancer therapy.

Pancreatic cancer is the fourth leading cancer with 85% mortality rate in USA alone and it is prevalent in many other developed and developing countries. Clinically, gemcitabine is prescribed as the first line chemotherapeutic drug for pancreatic cancer treatment. Gemcitabine-loaded poly(lactide-co-glycolide) (PLGA) nanospheres were synthesized and their physico-chemical properties were evaluated. The FESEM images showed that the gemcitabine loaded and blank nanospheres were 180 nm and 200 nm, respectively. The optimized encapsulation efficiency of gemcitabine was 15%. It was observed that 100% of gemcitabine was released from the PLGA nanospheres for 41 days in phosphate buffered saline (PBS) at pH7.4. The uptake of nanospheres in MiaPaCa-2 cells was studied using sulforhodamine B loaded PLGA nanospheres and our results showed that the nanospheres were taken up within 3h. Furthermore, the cytotoxicity of PLGA nanospheres loaded with gemcitabine showed a relative decrease in IC50 in MiaPaCa-2 and ASPC-1 pancreatic cancer cells in comparison to free gemcitabine. The study demonstrates that this system hold promise to improve the therapeutic efficacy of gemcitabine in vitro.

P56 * CONVECTION-ENHANCED DELIVERY (CED) OF CARBOPLATIN NANOSPHERES FOR THE TREATMENT OF GLIOBLASTOMA

INTRODUCTION: We are currently investigating CED of the platinum-based drug, carboplatin as a novel treatment strategy for high grade glioma in adults and children. Although initial results show significant promise, our current treatment strategy requires intermittent infusions due to rapid clearance of carboplatin from the brain. Furthermore, carboplatin is not specifically toxic to tumour cells and has been associated with neurotoxicity at high infused concentrations. We sought to encapsulate carboplatin in lactic acid-glycolic acid copolymer (PLGA) to develop a novel drug delivery system with improved safety and persistence within the brain and increased cancer cytotoxicity. METHOD: We compared the neuronal and tumour cytotoxicity of free carboplatin with encapsulated carboplatin in primary neuronal and GBM cultures. We studied distribution, tissue clearance and toxicity of carboplatin nanospheres following intrastriatal CED in rats. RESULTS: Encapsulation of carboplatin in PLGA nanospheres conferred greater tumour cytotoxicity, reduced neuronal toxicity and prolonged tissue half-life compared with the free drug. CONCLUSION: Encapsulation of carboplatin in PLGA onfers increased safety, with significant increases in tumour cytotoxicity and persistence within the brain. Further investigation is required to determine the translational potential of using PLGA encapsulated-carboplatin as a novel anti-glioma treatment strategy.

Preparation and characterization of PLGA nanospheres loaded with inactivated influenza virus, CpG-ODN and Quillaja saponin.

The purpose of this study was preparation and evaluation of PLGA nanospheres containing the influenza virus and different adjuvants, Quillaja saponin (QS) and CpG-ODN. Nanospheres were prepared using the double emulsion-solvent evaporation method. The morphological and physicochemical properties were studied by scanning electron microscopy (SEM), determination of zeta potential, encapsulation efficiency and release profile. The particle size of formulations was less than 1000 nm, except for formulations containing antigen. The results were confirmed with SEM images. Encapsulation efficiency of antigen, QS and CpG ODN were 80%, 62% and 31%, respectively. The zeta potential of nanospheres was about -30 mV. The burst release was observed for all encapsulates and reached to about 48%, 44% and 35% within 90 min for antigen, CpG-ODN and Qs content, respectively. The formulations showed proper physicochemical properties. These nanospheres have good potential to be used as delivery systems/adjuvants for immunization against influenza.

Continued sustained release of VEGF by PLGA nanospheres modified BAMG stent for the anterior urethral reconstruction of rabbit

ObjectiveTo study the biocompatibility and neovascularization of the PLGA nanospheres wrapped with vascular endothelial growth factor (VEGF), which can improve bladder acellular matrix graft (BAMG) with local continuous release of VEGF. MethodsA total of 18 rabbit model (length of stenosis: 3cm) with anterior urethral stricture were used as experimental animals and divided into three groups. Group A as the control group: Simple BAMG scaffold materials for urethral reconstruction. Group B as the blank group: PLGA microspheres modified BAMG for urethral reconstruction. Group C: PLGA conjugated with VEGF and modified BAMG for the urethral reconstruction. All rabbits underwent urethral angiography after 7 days, 15 days, 1 month and 3 months after the operation, and one rabbit in each group was sacrificed to be prepared for the organization histologic examination, HE staining, masson staining, CD31, 34 and a-SAM immunohistochemical detection in the repaired sites. ResultsIn group A, significant urethral restenosis occurred in two rabbits after 15 days of the operation, HE and masson staining showed a lot of collagen arranged in the repaired sites, and there were a large number of inflammatory cell infiltration, and there were also CD31, 34 in the repaired sites. a-SAM microvascular tag count showed a small amount of microvascular; Group B showed anastomotic restenosis, HE and masoon staining showed inflammatory cell infiltration and collagen deposition; Group C: urethrography showed lumen patency. There were a small amount of inflammatory cell infiltration after 7 and 15 days after the operation, and there were also CD31, 34 in the repaired sites. The a-SAM microvascular tag count showed many microvascular. And the difference was significant. ConclusionsAnterior urethral reconstruction with sustained-release of VEGF by PLGA nanospheres modified BAMG stents can reduce postoperative restenosis. It can also reduce collagen deposition and scar formation, promote angiogenesis of the repair tissue; therefore it in valuable in the tissue-engineered urethral reconstruction.

Flurbiprofen PLGA-PEG nanospheres: Role of hydroxy-β-cyclodextrin on ex vivo human skin permeation and in vivo topical anti-inflammatory efficacy

In this study, flurbiprofen (FB) loaded poly(d,l-lactide-co-glycolide) (PLGA) and PLGA with poly(ethylene glycol) (PLGA-PEG) nanospheres (NSs) with and without hydroxypropyl-β-cyclodextrin (HPβCD) were developed as skin controlled delivery systems. X-ray diffraction was used to determine the physical state of the entrapped drug. Results showed that the drug in PLGA NSs was present in the form of a molecular dispersion (dissolved state) in the polymers, whereas in PLGA-PEG NSs, the drug was present in both molecular dispersion and crystalline forms. Furthermore, HPβCD provided solubilization of the free FB present on the surface of the PLGA-PEG NSs and a complete amorphosization of the drug was obtained. Optical analyses using TurbiscanLab® demonstrated that HPβCD provided an efficient steric stability of the NSs, preventing particle aggregation. The ex vivo permeation profiles of the NSs and conventional FB solution were evaluated using human skin. Results demonstrated that only PLGA-PEG NSs showed slight permeation improvement. However, after 24h, the FB retained in the skin was about 9-fold higher with NSs compared with the control solution, attributed to the reservoir effect of NSs acting as a depot, sustaining the drug and limiting its systemic absorption. In vivo performance of NSs was evaluated by assessing anti-inflammatory efficacy in TPA-induced mouse ear edema. Topically applied NSs significantly decreased in vivo inflammation compared to the control solution and the anti-inflammatory efficacy of HPβCD NSs was stronger than NSs without HPβCD. In vivo skin irritation evaluated by the in vivo Draize test showed no irritation of the formulations tested.

Optimization of maghemite-loaded PLGA nanospheres for biomedical applications

Magnetic nanoparticles have been proposed as interesting tools for biomedical purposes. One of their promising utilization is the MRI in which magnetic substances like maghemite are used in a nanometric size and encapsulated within locally biodegradable nanoparticles. In this work, maghemite has been obtained by a modified sol–gel method and encapsulated in polymer-based nanospheres. The nanospheres have been prepared by single emulsion evaporation method. The different parameters influencing the size, polydispersity index and zeta potential surface of nanospheres were investigated. The size of nanospheres was found to increase as the concentration of PLGA increases, but lower sizes were obtained for 3min of sonication time and surfactant concentration of 1%. Zeta potential response of magnetic nanospheres towards pH variation was similar to that of maghemite-free nanospheres confirming the encapsulation of maghemite within PLGA nanospheres. The maghemite entrapment efficiency and maghemite content for nanospheres are 12% and 0.59% w/w respectively.

CHARACTERIZATION AND TOXICITY OF CARBON DOT-POLY(LACTIC-CO-GLYCOLIC ACID) NANOCOMPOSITES FOR BIOMEDICAL IMAGING

Semiconductor quantum dots (QDs) have achieved initial success as biomedical imaging agents. However, significant cytotoxicity in the biological environment prohibits their use in vivo. Here, we introduce nanocomposites composed of carbon dots (C-dots) in poly(lactic-co-glycolic acid) (PLGA) carriers as possible imaging agents for in vivo applications. An initial hurdle to clinical use is overcome by synthesizing C-dots with commercially available carbon black precursors, permitting scalable nanomanufacturing. These fluorescent nanoparticles, which have a mean diameter of ~1 nm, display a disordered graphitic structure. To overcome a second clinical hurdle (i.e., rapid renal clearance of nanoparticles &lt;~6 nm in diameter), C-dots were encapsulated in biodegradable PLGA nanospheres. The resulting nanocomposites showed a mean diameter of 344 ± 23 nm, which should reduce renal clearance. With further optimization, nanocarriers could be optimized to sizes &lt;200 nm to reduce accumulation in the reticuloendothelial system (RES). Toxicity of both C-dots and C-dot-PLGA nanocomposites was evaluated using HepG2 liver cell lines. Unlike QDs, which can induce toxicological responses at concentrations as low as 0.005 mg/mL, C-dots exhibited cytotoxicity at concentrations greater than 0.2 mg/mL, while their derived nanocomposites did not exhibit cytotoxicity at any concentration tested (i.e., 0.02 mg/mL, 0.1 mg/mL and 0.2 mg/mL).

Transdermal absorption enhancement of papain loaded in elastic niosomes incorporated in gel for scar treatment

Papain is one of the protease enzymes from Carica papaya latex which is widely used in dermatology for scar treatment. The aim of this study was to compare the penetration of papain from gel formulations containing niosomes and nanospheres loaded with papain. The vesicular sizes of all niosomes and nanospheres in the gel formulations were in the range of 220.7–520.2nm. Papain loaded in elastic niosomes and incorporated in gel exhibited the accumulate amounts and fluxes of 0.226mg/cm2 and 0.029mg/cm2/h in the whole rat skin and 0.220mg/cm2 and 0.037mg/cm2/h in the receiving solution, which were 3.10, 2.38 and 2.24, 2.25; 10.08, 7.78 and 4.92, 4.93; 4.86, 3.71 and 7.38, 7.38 times more than that from gel containing papain loaded in non-elastic niosomes, PLGA nanospheres and in solution, respectively, investigated by Franz diffusion cells at 6h. All gel formulations incorporated with papain loaded in niosomes and nanospheres gave no irritation on rabbit skin. Gel containing papain loaded in elastic niosomes gave superior chemical stability to gel containing free papain of 1.13, 1.29 and 1.35 times when stored at 4±2, 27±2 and 45±2°C after 3months, respectively. After 28days of application, gel containing papain loaded in elastic niosomes (GEN) exhibited higher reduction of hypertrophic scars of the induced scar on rabbits’ ears determined by a vernier caliper than gel base (GB), gel containing free papain (GS), and gel containing papain loaded in non-elastic niosomes (GNN) of 10.20, 2.73 and 2.31 times, respectively. For histological examination, the numbers of collagen fibres and the height of the scars treated with GEN were significantly decreased compared with the control group. This study has demonstrated the potential of niosomes, especially the elastic niosomes, for the enhancement of rat skin transdermal absorption of papain and the improvement of scar reduction in rabbit ear model which will be beneficial for the development of topical products for scar treatment.

Possibility for the development of cosmetics with PLGA nanospheres

The optimized preparation of Poly–(lactide-co-glycolic acid) (PLGA) nanospheres containing ubiquinone (UQ) for cosmetic products was pursued. By investigating various conditions for the preparation of UQ/PLGA nanospheres such as the molecular weight of PLGA, PLGA concentration, and UQ concentration, UQ/PLGA nanospheres with increased stability and slower drug release at a higher drug loading efficiency were prepared. Permeation tests on the prepared nanospheres using iontophoresis via electric dermal administration on membrane filters (200 nm pore size) and hairless mouse skin samples were also carried out. After iontophoresis, the nanospheres choked the membrane filter and remained on the horny layer of the hairless mouse skin, even after washing. Therefore, the prepared UQ/PLGA nanospheres and the established iontophoresis technique with the PLGA nanospheres in the present study can be applied to the future development of cosmetics.

Chemical stability enhancement and cytotoxicity reduction of papain loaded in PLGA nanospheres

Poly(lactic-co-glycolic acid) (PLGA) nanospheres loaded with papain were prepared by the emulsion solvent diffusion in water (ESD) and the w/o/w emulsion solvent evaporation (ESE) methods. The nanosphere loaded with papain from the ESE method gave smaller particle sizes (220–232 nm) and higher encapsulation efficiency of about two-folds than those from the ESD method. The morphology of the nanospheres loaded with papain prepared by the ESE method exhibited spherical shape and smooth surface investigated by SEM and TEM. The release profile of papain from the PLGA nanospheres of the ESD and ESE method indicated two phases with an initial rapid phase of 6 h and followed by the slow release phase of 48 h. The unloaded PLGA nanospheres from the two methods did not show any cytotoxicity in human skin fibroblasts, while the unloaded papain gave toxicity more than the loaded papain of 1.5 times. Papain loaded in PLGA nanospheres prepared by the ESE method was more chemical stable than the unloaded papain of eight and three times when kept at 4°C and 25°C for 6 weeks, respectively. The developed stable and low cytotoxic nanosphere loaded with papain can be further developed as topical products.