In Vitro Enhanced Osteogenic Potential of Human Mesenchymal Stem Cells Seeded in a Poly (Lactic-co-Glycolic) Acid Scaffold: A Systematic Review

Study Design

Human bone marrow stem cells (hBMSCs) and human adipose-derived stem cells (hADSCs) have demonstrated the capability to regenerate bone once they have differentiated into osteoblasts.

Objective

This systematic review aimed to evaluate the in vitro osteogenic differentiation potential of these cells when seeded in a poly (lactic-co-glycolic) acid (PLGA) scaffold.

Methods

A literature search of 4 databases following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was conducted in January 2021 for studies evaluating the osteogenic differentiation potential of hBMSCs and hADSCs seeded in a PLGA scaffold. Only in vitro models were included. Studies in languages other than English were excluded.

Results

A total of 257 studies were identified after the removal of duplicates. Seven articles fulfilled our inclusion and exclusion criteria. Four of these reviews used hADSCs and three used hBMSCs in the scaffold. Upregulation in osteogenic gene expression was seen in all the cells seeded in a 3-dimensional scaffold compared with 2-dimensional films. High angiogenic gene expression was found in hADSCs. Addition of inorganic material to the scaffold material affected cell performance.

Conclusions

Viability, proliferation, and differentiation of cells strongly depend on the environment where they grow. There are several factors that can enhance the differentiation capacity of stem cells. A PLGA scaffold proved to be a biocompatible material capable of boosting the osteogenic differentiation potential and mineralization capacity in hBMSCs and hADSCs.

Preliminary study on a novel biological scaffold loaded with Apelin13 sustainedrelease microcapsules for promoting fallopian tube recanalization in rabbits

OBJECTIVES

Tubal factor infertility severely impairs the natural fertility of women, and there is for genuine tubal recanalization, including restoration of both the anatomy and function of the diseased fallopian tubes. Currently, there is no effective treatment available. This study aims to explore methods for promoting the repair and recanalization of fallopian tubes from these 2 aspects.

METHODS

Apelin-13 sustained-release microspheres and poly (lactic-co-glycolic acid) (PLGA) three-dimensional (3D) biodegradable scaffolds were prepared. The basic characteristics and in vivo degradation (mass loss rate) of the biodegradable scaffolds were tested, along with the in vitro drug release (cumulative release rate), the in vivo drug release (Apelin-13 plasma concentration), and in vitro degradation (degradation rate) of the microspheres. The Apelin-13 microspheres (microsphere group)/PLGA 3D scaffolds loaded with Apelin-13 sustained-release microspheres (scaffold-microcapsule group) were injected/placed into the fallopian tubes of New Zealand rabbit of chronic salpingitis models. The patency, microscopic structure, and positive expression of estrogen receptor and progesterone receptor of the fallopian tubes in the control group, the model group, the microcapsule group, and the scaffold-microcapsule group was observed and compared.

RESULTS

At the 4th week post-operation, the mass loss rate of the PLGA 3D scaffolds, the degradation rate of the microspheres, and the Apelin-13 sustained-release microspheres-generated cumulative release rate in vitro over 30 days were 98.66%, 70.58%, and 98.68% respectively. The plasma concentration of Apelin-13 reached its peak within 5 days and remained stable for 25 days. Compared with the model and microsphere groups, the scaffold-microsphere group showed a milder inflammatory reaction within the tubal lumen, a higher rate of fallopian tube patency, and higher expression levels of estrogen and progesterone receptors (all P<0.05). The indicators of the scaffold-microsphere group were close to those of the control group.

CONCLUSIONS

The PLGA 3D scaffolds loaded with Apelin-13 sustained-release microspheres can comprehensively repair the anatomical structure and physiological function of the fallopian tubes and hold promise for truly effective tubal recanalization.

Cationic Nanoparticle-Stabilized Vaccine Delivery System for the H9N2 Vaccine to Promote Immune Response in Chickens

Chinese yam polysaccharides (CYPs) have received wide attention for their immunomodulatory activity. Our previous studies had discovered that the Chinese yam polysaccharide PLGA-stabilized Pickering emulsion (CYP-PPAS) can serve as an efficient adjuvant to trigger powerful humoral and cellular immunity. Recently, positively charged nano-adjuvants are easily taken up by antigen-presenting cells, potentially resulting in lysosomal escape, the promotion of antigen cross-presentation, and the induction of CD8 T-cell response. However, reports on the practical application of cationic Pickering emulsions as adjuvants are very limited. Considering the economic damage and public-health risks caused by the H9N2 influenza virus, it is urgent to develop an effective adjuvant for boosting humoral and cellular immunity against influenza virus infection. Here, we applied polyethyleneimine-modified Chinese yam polysaccharide PLGA nanoparticles as particle stabilizers and squalene as the oil core to fabricate a positively charged nanoparticle-stabilized Pickering emulsion adjuvant system (PEI-CYP-PPAS). The cationic Pickering emulsion of PEI-CYP-PPAS was utilized as an adjuvant for the H9N2 Avian influenza vaccine, and the adjuvant activity was compared with the Pickering emulsion of CYP-PPAS and the commercial adjuvant (aluminum adjuvant). The PEI-CYP-PPAS, with a size of about 1164.66 nm and a ζ potential of 33.23 mV, could increase the H9N2 antigen loading efficiency by 83.99%. After vaccination with Pickering emulsions based on H9N2 vaccines, PEI-CYP-PPAS generated higher HI titers and stronger IgG antibodies than CYP-PPAS and Alum and increased the immune organ index of the spleen and bursa of Fabricius without immune organ injury. Moreover, treatment with PEI-CYP-PPAS/H9N2 induced CD4⁺ and CD8⁺ T-cell activation, a high lymphocyte proliferation index, and increased cytokine expression of IL-4, IL-6, and IFN-γ. Thus, compared with the CYP-PPAS and aluminum adjuvant, the cationic nanoparticle-stabilized vaccine delivery system of PEI-CYP-PPAS was an effective adjuvant for H9N2 vaccination to elicit powerful humoral and cellular immune responses.

The Idiosyncratic Efficacy of Spironolactone-Loaded PLGA Nanoparticles Against Murine Intestinal Schistosomiasis

Background

Schistosomiasis is a chronic debilitating parasitic disease accompanied with severe mortality rates. Although praziquantel (PZQ) acts as the sole drug for the management of this disease, it has many limitations that restrict the use of this treatment approach. Repurposing of spironolactone (SPL) and nanomedicine represents a promising approach to improve anti-schistosomal therapy. We have developed SPL-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) to enhance the solubility, efficacy, and drug delivery and hence decrease the frequency of administration, which is of great clinical value.

Methods

The physico-chemical assessment was performed starting with particle size analysis and confirmed using TEM, FT-IR, DSC, and XRD. The antischistosomal effect of the SPL-loaded PLGA NPs against Schistosoma mansoni (S. mansoni)-induced infection in mice was also estimated.

Results

Our results manifested that the optimized prepared NPs had particle size of 238.00 ± 7.21 nm, and the zeta potential was -19.66 ± 0.98 nm, effective encapsulation 90.43±8.81%. Other physico-chemical features emphasized that nanoparticles were completely encapsulated inside the polymer matrix. The in vitro dissolution studies revealed that SPL-loaded PLGA NPs showed sustained biphasic release pattern and followed Korsmeyer-Peppas kinetics corresponding to Fickian diffusion (n<0.45). The used regimen was efficient against S. mansoni infection and induced significant reduction in spleen, liver indices, and total worm count (ρ<0.05). Besides, when targeting the adult stages, it induced decline in the hepatic egg load and the small intestinal egg load by 57.75% and 54.17%, respectively, when compared to the control group. SPL-loaded PLGA NPs caused extensive damage to adult worms on tegument and suckers, leading to the death of the parasites in less time, plus marked improvement in liver pathology.

Conclusion

Collectively, these findings provided proof-of-evidence that the developed SPL-loaded PLGA NPs could be potentially used as a promising candidate for new antischistosomal drug development.

Osteotome-mediated sinus floor elevation using an in situ hardening biphasic calcium phosphate bone graft substitute compared to xenograft: A randomized controlled clinical trial

Aim

To assess osteotome-mediated sinus floor elevation (OMSFE) with simultaneous implant placement using an in situ hardening biphasic calcium phosphate (BCP) compared to xenograft as a control.

Methods

Patient in need for sinus floor augmentation in one or both sinuses were selected for this randomised controlled clinical trial. Sites presenting a residual sinus floor height of 3-6 mm and eligible for OMSFE were randomly assigned to receive either BCP (test) or xenograft particles (control). CBCT scans were performed before and at the time of implant loading (180 days). The difference in sinus floor height gain between the two groups was set as the primary endpoint parameter for equivalence testing. The implant insertion torque (ITV) was recorded and Implant stability quotients (ISQ) was assessed upon implant placement, abutment connection (160 days) and implant loading (180 days).

Results

A total of 54 sinus lifts were performed in 42 patients including 12 bilateral cases. Four implants failed (two in each group) and a total of six patients were lost to follow-up. Statistical analysis of sinus floor height revealed no significant differences (p < 0.05) between groups at baseline nor at 180 days after augmentation. There was no statistical difference in sinus floor height gain between the two groups as supported by the 90% confidence intervals of the difference between groups. Good primary implant stability was confirmed in both treatment groups by ITV and ISQ measurements.

Conclusions

Within the limits of this study, it can be concluded that OMSFE using in situ hardening BCP particles results in equivalent sinus floor height gain than using xenograft particles but offers an easier application.

Prime Vaccination with Chitosan-Coated Phipps BCG and Boosting with CFP-PLGA against Tuberculosis in a Goat Model

Simple Summary

Bovine tuberculosis is a disease that affects cattle and other animal species worldwide and represents a risk to public health. Even though there is a vaccine that has been used to control tuberculosis in humans for almost 100 years, up to now, it has not been used in animals. The reason is that vaccination interferes with the tuberculin test, the current test to diagnose tuberculosis in the field, and shows an inconsistent efficacy in animals. Recent studies report that prime vaccinating with BCG and boosting with proteins vaccinations perform better. In addition, there are reports that some polymers increase the immune response against various infectious diseases; therefore, testing a vaccine formula with polymers sounds like a wise thing to do. In this study, we showed that priming with BCG and boosting with a culture filtrate protein, alone or in combination with a polymer, the number of animals with lesions, the number of lesions per animal, and the size of the lesions in vaccinated animals, compared with those not vaccinated or those vaccinated with BCG alone, are significantly reduced. Our results mean that a vaccination used as a complement of actual tuberculosis control programs in animal populations can be useful to reduce tuberculosis dissemination.

Abstract

Attempts to improve the immune response and efficacy of vaccines against tuberculosis in cattle, goats, and other animal species have been the focus of research in this field during the last two decades. Improving the vaccine efficacy is essential prior to running long-lasting and expensive field trials. Studies have shown that vaccine protocols utilizing boosting with proteins improve the vaccine efficacy. The use of polymers such as chitosan and PolyLactic-co-Glycolic Acid (PLGA) improves the immune response against different diseases by improving the interaction of antigens with the cellular immune system and modulating the host immune response. This study shows that the prime BCG vaccination, boosted with a culture filtrate protein (CFP), alone or in combination with chitosan and PolyLactic-co-Glycolic Acid (PLGA), have the potential to reduce tuberculosis (TB) dissemination by reducing the number of animals with lesions, the number of lesions per animal, and the size of the lesions in vaccinated animals, compared with those not vaccinated or those vaccinated with BCG alone. The vaccinated groups showed significantly higher Interferon-γ levels in the blood compared to the control, nonvaccinated group after vaccination, after boosting, and after the challenge with the wild-type Mycobacterium bovis strain.

Poly (Lactic-co-Glycolic Acid) Nanoparticles and Nanoliposomes for Protein Delivery in Targeted Therapy: A Comparative In Vitro Study

Over the previous years, the design, development, and potential application of nanocarriers in the medical field have been intensively studied for their ability to preserve drug properties, especially their pharmacological activity, and to improve their bioavailability. This work is a comparative study between two different types of nanocarriers, poly (lactic-co-glycolic acid)-based nanoparticles and phosphatidylcholine-based nanoliposomes, both prepared for the encapsulation of bovine serum albumin as a model protein. Polymeric nanoparticles were produced using the double emulsion water-oil-water evaporation method, whereas nanoliposomes were obtained by the thin-film hydration method. Both nanocarriers were characterized by morphological analysis, particle mean size, particle size distribution, and protein entrapment efficiency. Invitro release studies were performed for 12 days at 37 °C. In order to explore a possible application of these nanocarriers for a targeted therapy in the cardiovascular field, hemolytic activity and biocompatibility, in terms of cell viability, were performed by using human red blood cells and EA.hy926 human endothelial cell line, respectively.

A Regenerative Polymer Blend Composed of Glycylglycine ethyl ester-substituted Polyphosphazene and Poly (lactic-co-glycolic acid)

In the pursuit of continuous improvement in the area of biomaterial design, blends of mixed-substituent polyphosphazenes and poly (lactic acid-glycolic acid) (PLGA) were prepared, and their morphology of phase distributions for the first time was studied. The degradation mechanism and osteocompatibility of the blends were also evaluated for their use as regenerative materials. Poly [(ethyl phenylalanato)25(glycine ethyl glycinato)75phosphazene](PNEPAGEG) and poly [(glycine ethyl glycinato)75(phenylphenoxy)25phosphazene](PNGEGPhPh) were blended with PLGA at various weight ratios to yield different blends, namely PNEPAGEG-PLGA 25:75, PNEPAGEG-PLGA 50:50, PNGEGPhPh-PLGA 25:75, and PNGEGPhPh-PLGA 50:50. The molecular interactions, domain sizes, and phase distributions of the blends were confirmed by atomic force microscopy (AFM) as the PNEPAGEG-PLGA and PNGEGPhPh-PLGA blends showed different domain sizes and phase distributions. Due to the extensive hydrogen bonding within the two polymer components, PNEPAGEG-PLGA exhibited small-sized domains and well-distributed morphology. While for the PNGEGPhPh-PLGA blends, the presence of phenylphenol (PhPh) caused the formation of PLGA large-sized domains as the PLGA formed a continuous phase and PNGEGPhPh constituted a dispersed phase. In addition to AFM results, scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDS), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and Fourier transform infrared spectroscopy (FTIR) results demonstrated the miscibility of the blends. The PNEPAGEG-PLGA and PNGEGPhPh-PLGA blends presented in situ 3D interconnected porous structures upon degradation in phosphate-buffered saline (PBS) media at 37°C. However, the blends showed different mechanistic pathways to the formations of the pores. The difference in the erosion patterns could be attributed to the nature of molecular attractions that exist in the blends. Furthermore, the novel blends were able to support cell growth as compared to PLGA, and accommodate cell infiltrations, which ultimately augmented surface area for better cell-material interactions.

Aligned Biofunctional Electrospun PLGA-LysoGM1 Scaffold for Traumatic Brain Injury Repair

Due to poor regenerative capabilities of the brain, a treatment for traumatic brain injury (TBI) presents a serious challenge to modern medicine. Biofunctional scaffolds that can support neuronal growth, guide neurite elongation, and re-establish impaired brain tissues are urgently needed. To this end, we developed an aligned biofunctional scaffold (aPLGA-LysoGM1), in which poly (lactic-co-glycolic acid) (PLGA) was functionalized with sphingolipid ceramide N-deacylase (SCDase)-hydrolyzed monosialotetrahexosylganglioside (LysoGM1) and electrospinning was used to form an aligned fibrous network. As a ganglioside of neuronal membranes, the functionalized LysoGM1 endows the scaffold with unique biological properties favoring the growth of neuron and regeneration of injured brain tissues. Moreover, we found that the aligned PLGA-LysoGM1 fibers acted as a topographical cue to guide neurite extension, which is critical for organizing the formation of synaptic networks (neural networks). Systematic in vitro studies demonstrated that the aligned biofunctional scaffold promotes neuronal viability, neurite outgrowth, and synapse formation and also protects neurons from pressure-related injury. Additionally, in a rat TBI model, we demonstrated that the implantation of aPLGA-LysoGM1 scaffold supported recovery from brain injury, as more endogenous neurons were found to migrate and infiltrate into the defect zone compared with alternative scaffold. These results suggest that the aligned biofunctional aPLGA-LysoGM1 scaffold represents a promising therapeutic strategy for brain tissue regeneration following TBI.

[Anti-CD206 antibody-conjugated Fe3O4-based PLGA nanoparticles selectively promotes M1 polarization of tumorassociated macrophages in mice]

OBJECTIVE

To enhance the anti-tumor immunity of macrophages by increasing iron concentration in the macrophages using nanospheres.

METHODS

Anti-CD206 antibody-conjugated Fe₃O₄-based polylactic acid glycolic acid (CD206- Fe₃O₄-PLGA) nanoparticles were prepared with the W/O/W method. The particle diameter was measured using Malvern particle size detector, the Zeta potential was determined using Zeta potentiometry, and the encapsulation efficiency of Fe₃O₄ was determined using an iron determination kit. The macrophage-binding and targeting abilities of the conjugated nanoparticles were evaluated using immunofluorescence assay, and the polarization index of macrophages was determined with Western blotting and qRT-PCR. BALB/C-57 mouse models bearing subcutaneous tumors were used to verify the efficacy of the nanoparticles to promote polarization of the tumor-associated macrophages (TAMs).

RESULTS

The conjugated nanoparticles had a mean diameter of 260-295 nm with Zeta potential values ranging from -19 mV to -33 mV, encapsulation efficiency of Fe₃O₄ ranging from 65% to 75%, and anti-CD206 conjunction efficiency of 65%-70%. Immunofluorescence assay verified the targeted binding ability of the nanoparticles with M2 macrophages. Western blotting and qRT-PCR confirmed that both CD206-Fe₃O₄-PLGA and Fe₃O₄-PLGA nanoparticles promoted the expression of TNF-α, iNOS and IL-1β (P < 0.05). In the tumor-bearing mouse models, CD206-Fe₃O₄-PLGA nanoparticles were confirmed to promote CD86 expression in the TAMs.

CONCLUSIONS

CD206-Fe₃O₄-PLGA nanoparticles are capable of targeted binding to M2 macrophages and reversing the M2 macrophages to M1 phenotype by releasing coated iron oxide particles.

Preparation and Characterization of Surface Heat Sintered Nanohydroxyapatite and Nanowhitlockite Embedded Poly (Lactic-co-glycolic Acid) Microsphere Bone Graft Scaffolds: In Vitro and in Vivo Studies

In the context of using bone graft materials to restore and improve the function of damaged bone tissues, macroporous biodegradable composite bone graft scaffolds have osteoinductive properties that allow them to provide a suitable environment for bone regeneration. Hydroxyapatite (HAP) and whitlockite (WLKT) are the two major components of hard tissues such as bone and teeth. Because of their biocompatibility and osteoinductivity, we synthesized HAP (nHAP) and WLKT nanoparticles (nWLKT) by using the chemical precipitation method. The nanoparticles were separately incorporated within poly (lactic-co-glycolic acid) (PLGA) microspheres. Following this, the composite microspheres were converted to macroporous bone grafts with sufficient mechanical strength in pin or screw shape through surface sintering. We characterized physico-chemical and mechanical properties of the nanoparticles and composites. The biocompatibility of the grafts was further tested through in vitro cell adhesion and proliferation studies using rabbit bone marrow stem cells. The ability to promote osteogenic differentiation was tested through alkaline phosphate activity and immunofluorescence staining of bone marker proteins. For in vivo study, the bone pins were implanted in tibia bone defects in rabbits to compare the bone regeneration ability though H&E, Masson's trichrome and immunohistochemical staining. The results revealed similar physico-chemical characteristics and cellular response of PLGA/nHAP and PLGA/nWLKT scaffolds but the latter is associated with higher osteogenic potential towards BMSCs, pointing out the possibility to use this ceramic nanoparticle to prepare a sintered composite microsphere scaffold for potential bone grafts and tissue engineered implants.

Exploring Trehalose on the Release of Levonorgestrel from Implantable PLGA Microneedles

Hydrophobic drugs wrapped in poly (lactic-co-glycolic acid) (PLGA)-based microneedles (MNs) require a long time to release completely. To obtain the desired duration, it is still necessary to modulate the release of hydrophobic drugs from MNs, while the PLGA composition is unchangeable. In this work, implantable PLGA microneedles (IPMNs) composed of PLGA arrowheads encapsulating levonorgestrel (LNG) and a water-soluble supporting array were designed. We explored trehalose used as a porogen on the release of hydrophobic LNG from PLGA-based MNs. Varying the trehalose content in PLGA arrowheads could induce different rates of drug release. The highest cumulative release of LNG was 76.2 ± 3.9% for IPMNs with 33.3% trehalose during 21 days in vitro, while the cumulative release of LNG was 60.4 ± 3.5% for IPMNs without trehalose. Pharmacokinetic results in rats showed that plasma levels of LNG were sustained for 13 days for IPMNs with 33.3% trehalose and 16 days for IPMNs without trehalose. Furthermore, the PLGA arrowheads with trehalose degraded more rapidly than those without trehalose over 21 days in rats. Consequently, using trehalose as a porogen was a feasible approach to modulate the release of a hydrophobic drug from PLGA-based MNs.

Recent Advances in Nanoencapsulation Systems Using PLGA of Bioactive Phenolics for Protection against Chronic Diseases

Plant-derived polyphenolic compounds have gained widespread recognition as remarkable nutraceuticals for the prevention and treatment of various disorders, such as cardiovascular, neurodegenerative, diabetes, osteoporosis, and neoplastic diseases. Evidence from the epidemiological studies has suggested the association between long-term consumption of diets rich in polyphenols and protection against chronic diseases. Nevertheless, the applications of these phytochemicals are limited due to its low solubility, low bioavailability, instability, and degradability by in vivo and in vitro conditions. Therefore, in recent years, newer approaches have been attempted to solve the restrictions related to their delivery system. Nanoencapsulation of phenolic compounds with biopolymeric nanoparticles could be a promising strategy for protection and effective delivery of phenolics. Poly(lactic-co-glycolic acid) (PLGA) is one of the most successfully developed biodegradable polymers that has attracted considerable attention due to its attractive properties. In this review, our main goal is to cover the relevant recent studies that explore the pharmaceutical significance and therapeutic superiority of the advance delivery systems of phenolic compounds using PLGA-based nanoparticles. A summary of the recent studies implementing encapsulation techniques applied to polyphenolic compounds from plants confirmed that nanoencapsulation with PLGA nanoparticles is a promising approach to potentialize their therapeutic activity.

PHBV/PLGA nanoparticles for enhanced delivery of 5-fluorouracil as promising treatment of colon cancer

5-Fluorouracil (5-FU) is one of the most widely used agents in the first-line chemotherapy for colon cancer. However, clinical use of 5-FU is limited because of the low efficacy of drug uptake and systemic toxic effects. Therefore, there is a critical need to find better drug delivery systems in order to improve the efficacy of the drug. In the present study, we have developed a novel combination drug delivery system based on PHBV/PLGA NPs for delivery of 5-FU to cancer cells. NPs were prepared by the double emulsion method and their optimization of preparation was evaluated using Box-Behnken design (BBD) of response surface methodology (RSM). 5-FU loaded NPs were characterized by scanning electron microscope (SEM), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), and Fourier transformed infra-red spectroscopy (FT-IR). SEM image implied that NPs were spherical in shape and the results of DSC, TGA, and FT-IR suggest that 5-FU was encapsulated into NPs. The obtained results revealed that 5-FU loaded PHBV/PLGA NPs induced significant higher cell death at concentration much lower than free 5-FU. Results of hemolysis assay indicated that the NPs were hemo-compatible. In vivo anti-tumor studies showed that 5-FU loaded NPs reduced tumor volume significantly in comparison with free 5-FU. As the first example of using PHBV/PLGA as nano-drug delivery system with enhanced anti-tumor activities, this study establishes PHBV/PLGA as a novel promising drug delivery platform for treatment of colon cancer.

Three Dimensional Printing Bilayer Membrane Scaffold Promotes Wound Healing

Full-thickness skin wounds are common and could be a heavy physical and economic burden. With the development of three dimensional (3D) printing technology, skin-like constructs have been fabricated for skin wound healing and regeneration. Although the 3D printed skin has great potential and enormous advantages before vascular networks can be well-constructed, living cells are not recommended for 3D skin printing for in vivo applications. Herein, we designed and printed a bilayer membrane (BLM) scaffold consisting of an outer poly (lactic-co-glycolic acid) (PLGA) membrane and a lower alginate hydrogel layer, which respectively mimicked the skin epidermis and dermis. The multi-porous alginate hydrogel of the BLM scaffolds promoted cell adhesion and proliferation in vitro, while the PLGA membrane prevented bacterial invasion and maintained the moisture content of the hydrogel. Skin regeneration using the bilayer scaffold was compared with that of PLGA, alginate hydrogel and the untreated defect in vivo. Tissue samples were analyzed using histopathological and immunohistochemical staining of CD31. In addition, mRNA expression levels of collagen markers [collagen type 1 alpha 1 (COL1a1) and collagen type 3 alpha 1 (COL3a1)] and inflammatory markers [interleukin-1β (IL-1β), as well as tumor necrosis factor (TNF-α)] were measured. Conclusively, the application of BLM scaffold resulted in highest levels of best skin regeneration by increasing neovascularization and boosting collagen I/III deposition. Taken together, the 3D-printed BLM scaffolds can promote wound healing, and are highly suitable for a wide range of applications as wound dressings or skin substitutes.

Generational Biodegradable and Regenerative Polyphosphazene Polymers and their Blends with Poly (lactic-co-glycolic acid)

New fields such as regenerative engineering have driven the design of advanced biomaterials with a wide range of properties. Regenerative engineering is a multidisciplinary approach that integrates the fields of advanced materials science and engineering, stem cell science, physics, developmental biology, and clinical translation for the regeneration of complex tissues. The complexity and demands of this innovative approach have motivated the synthesis of new polymeric materials that can be customized to meet application-specific needs. Polyphosphazene polymers represent this fundamental change and are gaining renewed interest as biomaterials due to their outstanding synthetic flexibility, neutral bioactivity (buffering degradation products), and tunable properties across the range. Polyphosphazenes are a unique class of polymers composed of an inorganic backbone with alternating phosphorus and nitrogen atoms. Each phosphorus atom bears two substituents, with a wide variety of side groups available for property optimization. Polyphosphazenes have been investigated as potential biomaterials for regenerative engineering. Polyphosphazenes for use in regenerative applications have evolved as a class to include different generations of degradable polymers. The first generation of polyphosphazenes for tissue regeneration entailed the use of hydrolytically active side groups such as imidazole, lactate, glycolate, glucosyl, or glyceryl groups. These side groups were selected based on their ability to sensitize the polymer backbone to hydrolysis, which allowed them to break down into non-toxic small molecules that could be metabolized or excreted. The second generation of degradable polyphosphazenes developed consisted of polymers with amino acid ester side groups. When blended with poly (lactic acid-co-glycolic acid) (PLGA), the feasibility of neutralizing acidic degradation products of PLGA was demonstrated. The blends formed were mostly partially miscible. The desire to improve miscibility led to the design of the third generation of degradable polyphosphazenes by incorporating dipeptide side groups which impart significant hydrogen bonding capability to the polymer for the formation of completely miscible polyphosphazene-PLGA blends. Blend system of the dipeptide-based polyphosphazene and PLGA exhibit a unique degradation behavior that allows the formation of interconnected porous structures upon degradation. These inherent pore-forming properties have distinguished degradable polyphosphazenes as a potentially important class of biomaterials for further study. The design considerations and strategies for the different generations of degradable polyphosphazenes and future directions are discussed.

Self-assembled nanoparticles of reduction-sensitive poly (lactic-co-glycolic acid)-conjugated chondroitin sulfate A for doxorubicin delivery: preparation, characterization and evaluation

In this study, reduction-sensitive self-assembled polymer nanoparticles based on poly (lactic-co-glycolic acid) (PLGA) and chondroitin sulfate A (CSA) were developed and characterized. PLGA was conjugated with CSA via a disulfide linkage (PLGA-ss-CSA). The critical micelle concentration (CMC) of PLGA-ss-CSA conjugate is 3.5 µg/mL. The anticancer drug doxorubicin (DOX) was chosen as a model drug, and was effectively encapsulated into the nanoparticles (PLGA-ss-CSA/DOX) with high loading efficiency of 15.1%. The cumulative release of DOX from reduction-sensitive nanoparticles was only 34.8% over 96 h in phosphate buffered saline (PBS, pH 7.4). However, in the presence of 20 mM glutathione-containing PBS environment, DOX release was notably accelerated and almost complete from the reduction-sensitive nanoparticles up to 96 h. Moreover, efficient intracellular DOX release of PLGA-ss-CSA/DOX nanoparticles was confirmed by CLSM assay in A549 cells. In vitro cytotoxicity study showed that the half inhibitory concentrations of PLGA-ss-CSA/DOX nanoparticles and free DOX against A549 cells were 1.141 and 1.825 µg/mL, respectively. Therefore, PLGA-ss-CSA/DOX nanoparticles enhanced the cytotoxicity of DOX in vitro. These results suggested that PLGA-ss-CSA nanoparticles could be a promising carrier for drug delivery.

[Fabrication of poly (lactic-co-glycolic acid)/decellularized articular cartilage extracellular matrix scaffold by three-dimensional printing technology and investigating its physicochemical properties]

Objective

To manufacture a poly (lactic-co-glycolic acid) (PLGA) scaffold by low temperature deposition three-dimensional (3D) printing technology, prepare a PLGA/decellularized articular cartilage extracellular matrix (DACECM) cartilage tissue engineered scaffold by combining DACECM, and further investigate its physicochemical properties.

Methods

PLGA scaffolds were prepared by low temperature deposition 3D printing technology, and DACECM suspensions was prepared by modified physical and chemical decellularization methods. DACECM oriented scaffolds were prepared by using freeze-drying and physicochemical cross-linking techniques. PLGA/DACECM oriented scaffolds were prepared by combining DACECM slurry with PLGA scaffolds. The macroscopic and microscopic structures of the three kinds of scaffolds were observed by general observation and scanning electron microscope. The chemical composition of DACECM oriented scaffold was analyzed by histological and immunohistochemical stainings. The compression modulus of the three kinds of scaffolds were measured by biomechanical test. Three kinds of scaffolds were embedded subcutaneously in Sprague Dawley rats, and HE staining was used to observe immune response. The chondrocytes of New Zealand white rabbits were isolated and cultured, and the three kinds of cell-scaffold complexes were prepared. The growth adhesion of the cells on the scaffolds was observed by scanning electron microscope. Three kinds of scaffold extracts were cultured with L-929 cells, the cells were cultured in DMEM culture medium as control group, and cell counting kit 8 (CCK-8) was used to detect cell proliferation.

Results

General observation and scanning electron microscope showed that the PLGA scaffold had a smooth surface and large pores; the surface of the DACECM oriented scaffold was rough, which was a 3D structure with loose pores and interconnected; and the PLGA/DACECM oriented scaffold had a rough surface, and the large hole and the small hole were connected to each other to construct a vertical 3D structure. Histological and immunohistochemical qualitative analysis demonstrated that DACECM was completely decellularized, retaining the glycosaminoglycans and collagen typeⅡ. Biomechanical examination showed that the compression modulus of DACECM oriented scaffold was significantly lower than those of the other two scaffolds ( P<0.05). There was no significant difference between PLGA scaffold and PLGA/DACECM oriented scaffold ( P>0.05). Subcutaneously embedded HE staining of the three scaffolds showed that the immunological rejections of DACECM and PLGA/DACECM oriented scaffolds were significantly weaker than that of the PLGA scaffold. Scanning electron microscope observation of the cell-scaffold complex showed that chondrocytes did not obviously adhere to PLGA scaffold, and a large number of chondrocytes adhered and grew on PLGA/DACECM oriented scaffold and DACECM oriented scaffold. CCK-8 assay showed that with the extension of culture time, the number of cells cultured in the three kinds of scaffold extracts and the control group increased. There was no significant difference in the absorbance ( A) value between the groups at each time point ( P>0.05).

Conclusion

The PLGA/DACECM oriented scaffolds have no cytotoxicity, have excellent physicochemical properties, and may become a promising scaffold material of tissue engineered cartilage.

Poly (lactide-co-glycolide) (PLGA) Scaffold Induces Short-term Nerve Regeneration and Functional Recovery Following Sciatic Nerve Transection in Rats

Peripheral nerve injury is an important cause of incapability and has limited available treatment. Autologous donor nerve implant is the golden standard treatment, however, may cause secondary deficits. Stem cells show positive results in preclinical settings, preserving tissue and function. We tested the efficacy of stem cells derived from human exfoliated deciduous teeth seeded in poly (lactide-co-glycolide) scaffolds in sciatic nerve transection model. Seventy-two adult male Wistar rats had 7-mm nerve gap bridge using scaffolds with (or without) stem cells. Animals were randomly divided into: sham-operated; sham-operated without scaffold; sham-operated + scaffold + stem cells; sciatic transection + no treatment; sciatic transection + acellular scaffolds; sciatic transection + scaffold + stem cells. Sciatic Functional Index and Ladder Rung Walking tests were performed before (-1), 14 and 28 days after surgery. Morphometric nerve measurement and muscle weights were assessed. Scaffolds with stem cells improved function in Sciatic Functional Index. Acellular scaffold was effective, promoting functional recovery and nerve regeneration following nerve injury. Scaffolds provide better nerve regeneration and functional recovery after sciatic transection. Despite cell therapy promoting faster recovery after sciatic transection in the Sciatic Index Score, stem cells did not improve functional and morphological recovery after nerve injury. This is the first study testing the potential use of scaffolds combined with stem cells in the early stages after injury. Scaffolds with stem cells could accelerate nerve recovery and favor adjuvant therapies, evidencing the need for further studies to increase the knowledge about stem cells' mechanisms.

3D Printing Bioactive PLGA Scaffolds Using DMSO as a Removable Solvent

Present bioprinting techniques lack the methodology to print with bioactive materials that retain their biological functionalities. This constraint is due to the fact that extrusion-based printing of synthetic polymers is commonly performed at very high temperatures in order to achieve desired mechanical properties and printing resolutions. Consequently, current methodology prevents printing scaffolds embedded with bioactive molecules, such as growth factors. With the wide use of mesenchymal stem cells (MSCs) in regenerative medicine research, the integration of growth factors into 3D printed scaffolds is critical because it can allow for inducible MSC differentiation. We have successfully incorporated growth factors into extrusion printed poly (lactic-co-glycolic acid) (PLGA) scaffolds by introducing dimethyl sulfoxide (DMSO) for low temperature printing. Mechanical testing results demonstrated significantly different compressive and tensile properties for PLGA scaffold printed with or without DMSO. In particular, the PLGA-DMSO scaffold displayed a highly stretchable feature compared to the regular PLGA scaffold. The cellular response of growth factor introduction was evaluated in vitro using human mesenchymal stem cells (hMSCs). By evaporating the DMSO after printing, we ensured that there was no cytotoxic effect on seeded hMSCs. The addition of lineage specific growth factors led to increased expression of corresponding genetic markers for chondrogenesis, osteogenesis, and adipogenesis. We concluded that the use of DMSO for 3D printed scaffold fabrication with bioactive items is a revolutionary methodology in advancing regenerative medicine. The incorporation of bioactive molecules opens pathways to more therapeutic uses for 3D printing in treating damaged or deteriorating native tissue.

[Preparation of multifunctional nanoparticles targeting tongue cancer and in vitro study]

OBJECTIVE

This study aims to prepare docetaxel (DOC)-loaded multifunctional nanoparticles containing indocyanine green (ICG) and perfluorohexane (PFH) as targeted drug delivery system, which is supplemented with stromal cellderived factor-1 (SDF-1), and characterize their properties.

METHODS

Multifunctional nanoparticles were prepared by using the double emulsion method. SDF-1 was covalently conjugated to the surface of the nanoparticles through thioether bonding. Their particle size, distribution, and surface potential were determined with the Malvern measuring instrument. The conjugation of SDF-1 was evaluated by confocal laser scanning microscope. Encapsulation efficiency (ELC), drug loading capacity (DLC), and release regularity of the nanoparticles were determined by high-performance liquid chromatography (HPLC). In vitro photothermal property was recorded by a thermal imager. The in vitro imaging capacity was observed by a photoacoustic instrument and an ultrasonic diagnostic apparatus. Targeting capability was assessed by flow cytometry. The cell activity on SCC-15 cells was checked by CCK-8 method.

RESULTS

The targeted multifunctional nanoparticles showed regularly sphericity. The diameter was (502.88±17.92) nm. The zeta potential was (-11.5±3.15) mV. ELC was 54.12%±1.74%. DLC was 1.08 mg·mL-1. In vitro drug release was initially fast and subsequently slow. The photothermal characteristics were related to the concentration; the higher the concentration, the higher the temperature. Nanoparticles could detect significant photoacoustic and ultrasound signals. The in vitro targeting rate was 89.99%. No significant differences of cell viability in the SINPs groups were observed at each concentration (P>0.05). The inhibition effect of DOC-SINPs was stronger than that of SINPs whether or not in the presence of laser irradiation among the groups of 150 and 200 μg·mL-1 (P<
0.05).

CONCLUSIONS

Multifunctional nanoparticles for diagnosis and treatment were successfully prepared and displayed dualmode ultrasound/photoacoustic imaging and antitumor effects of chemotherapy and photothermal therapy.

[Construction and bioactivity evaluation of hepatocyte growth factor-loaded poly (lactic-co-glycolic acid) nanoparticles]

OBJECTIVE

To explore the optimum conditions for preparing poly(lactic-co-glycolic) acid (PLGA) nanoparticles and evaluate the bioactivity of hepatocyte growth factor (HGF)-loaded PLGA nanoparticles.

METHODS

Bovine serum albumin (BSA)-loaded PLGA nanoparticles were prepared using a double emulsion-solvent evaporation method. The preparation process of nanoparticles was optimized by orthogonal test with the particle size, encapsulation efficiency (EE), drug loading (DD), and recovery as the indexes. HGF-loaded nanoparticles were then prepared under the optimized conditions. The EE, DD and release characteristics of BSA?loaded nanoparticles and HGF-loaded nanoparticles were evaluated using a BCA kit and HGF ELISA kit. The bioactivity of HGF-loaded nanoparticles was evaluated using CCK8 proliferation assay.

RESULTS

The HGF-loaded nanoparticles prepared under the optimized conditions had a uniform size with a mean diameter of 234.4∓4.8 nm, an EE of (77.75∓3.04)% and a recovery rate of (49.33∓9.34)%. The in vitro release curve highlighted an initial burst drug release followed by sustained release from the nanoparticles. HGF-loaded nanoparticles obviously promoted the proliferation of Hacat keratinocytes in vitro.

CONCLUSION

HGF-loaded nanoparticles prepared using double emulsion?solvent evaporation method under optimized conditions possesses a high EE with a good sustained drug release profile and a good bioactivity.

[Construction and bioactivity evaluation of hepatocyte growth factor-loaded poly (lactic-co-glycolic acid) nanoparticles]

OBJECTIVE

To explore the optimum conditions for preparing poly(lactic-co-glycolic) acid (PLGA) nanoparticles and evaluate the bioactivity of hepatocyte growth factor (HGF)-loaded PLGA nanoparticles.

METHODS

Bovine serum albumin (BSA)-loaded PLGA nanoparticles were prepared using a double emulsion-solvent evaporation method. The preparation process of nanoparticles was optimized by orthogonal test with the particle size, encapsulation efficiency (EE), drug loading (DD), and recovery as the indexes. HGF-loaded nanoparticles were then prepared under the optimized conditions. The EE, DD and release characteristics of BSA?loaded nanoparticles and HGF-loaded nanoparticles were evaluated using a BCA kit and HGF ELISA kit. The bioactivity of HGF-loaded nanoparticles was evaluated using CCK8 proliferation assay.

RESULTS

The HGF-loaded nanoparticles prepared under the optimized conditions had a uniform size with a mean diameter of 234.4∓4.8 nm, an EE of (77.75∓3.04)% and a recovery rate of (49.33∓9.34)%. The in vitro release curve highlighted an initial burst drug release followed by sustained release from the nanoparticles. HGF-loaded nanoparticles obviously promoted the proliferation of Hacat keratinocytes in vitro.

CONCLUSION

HGF-loaded nanoparticles prepared using double emulsion?solvent evaporation method under optimized conditions possesses a high EE with a good sustained drug release profile and a good bioactivity.

Immunochemotherapy mediated by thermosponge nanoparticles for synergistic anti-tumor effects

The efficacy of immunotherapy was demonstrated to be compromised by reduced immunogenicity of tumor cells and enhanced suppressive properties of the tumor microenvironment in cancer treatment. There is growing evidence that low-dose chemotherapy can modulate the immune system to improve the anti-tumor effects of immunotherapy through multiple mechanisms, including the enhancement of tumor immunogenicity and reversal of the immunosuppressive tumor microenvironment. Here, we fabricated thermosponge nanoparticles (TSNs) for the co-delivery of chemotherapeutic drug paclitaxel (PTX) and immunostimulant interleukin-2 (IL-2) to explore the synergistic anti-tumor effects of chemotherapy and immunotherapy. The distinct temperature-responsive swelling/deswelling character facilitated the effective post-entrapment of cytokine IL-2 in nanoparticles by a facile non-solvent mild incubation method with unaffected bioactivity and favorable pharmacokinetics. PTX and IL-2 co-loaded TSNs exhibited significant inhibition on tumor growth and metastasis, and prolonged overall survival for tumor-bearing mice compared with the corresponding monotherapies. The synergistic effect was evidenced from the remodeled tumor microenvironment in which low-dose chemotherapeutics disrupted the immunosuppressive tumor microenvironment and enhanced tumor immunogenicity, and immunostimulant cytokine promoted the anti-tumor immune response of immune effector cells. The immunochemotherapy mediated by this thermosponge nanoplatform may provide a promising treatment strategy against cancer.

Ultrasound molecular imaging with cRGD-PLGA-PFOB nanoparticles for liver fibrosis staging in a rat model

Hepatic fibrosis is the only chronic liver disease process that can be reversed. Developing non-invasive and effective methods to quantitatively assess the degree of liver fibrosis is of great clinical significance and remains a major challenge. The key factors in hepatic fibrosis pathogenesis are the activation and proliferation of hepatic stellate cells that subsequently express integrin α_vβ₃. An ultrasound (US) agent combined with a targeting peptide may be used for the early and non-invasive diagnosis of hepatic fibrosis. Herein, we report the synthesis of core-shell nanoparticles (NPs) successfully engineered by conjugation with cyclic arginine-glycine-aspartic acid (cRGD) octapeptide, allowing hepatic integrin α_vβ₃ targeting for liver fibrosis staging. This system consists of a perfluorooctyl bromide (PFOB) liquid in the core that is stabilized with a Poly (lactic-co-glycolic acid) (PLGA) polymer shell and modified with a cRGD. These core-shell NPs (cRGD-PLGA-PFOB NPs) exhibited useful US molecular imaging features including high imaging contrast among liver fibrotic stages and the adjacent tissues. Our results indicate that the cRGD-PLGA-PFOB NPs have significant potential to distinguish different liver fibrotic stages and could be used in clinical applications.

Control-released Alpha-lipoic acid-loaded PLGA microspheres enhance bone formation in type 2 diabetic rat model

Since diabetes lead to alterations in bone metabolism with reductions in bone mineral content and delayed bone formation, the most effective method for bone regeneration in diabetes remains to be determined. In this study, type 2 diabetes were successfully induced via a high-fat diet and low-dose streptozotocin intraperitoneal injection. Excess reactive oxygen species (ROS) has been implicated in diabetes mellitus. Overexpression of ROS can lead to oxidative stress and subsequently to H₂O₂-mediated impaired proliferation and delayed cellular differentiation. As a result, antioxidant alpha-lipoic acid (ALA)-loaded poly (lactic-co-glycolic acid) (PLGA) microspheres were fabricated using the emulsion solvent evaporation method, and a sustained and controlled release of ALA was observed up to 27 days. It was demonstrated that biodegradable PLGA microspheres loaded with ALA acted as ROS scavengers and partially recover the mesenchymal stem cell proliferation and differentiation. The bone formation of ALA loaded scaffolds in rat cranial bone defects were greater than the prime three-dimensional collagen scaffold. These results suggest the application of ALA loaded PLGA microsphere exhibit good bioactivity and bone forming ability in diabetes.

Poly(Lactic-co-Glycolic Acid): Applications and Future Prospects for Periodontal Tissue Regeneration

Periodontal tissue regeneration is the ultimate goal of the treatment for periodontitis-affected teeth. The success of regenerative modalities relies heavily on the utilization of appropriate biomaterials with specific properties. Poly (lactic-co-glycolic acid) (PLGA), a synthetic aliphatic polyester, has been actively investigated for periodontal therapy due to its favorable mechanical properties, tunable degradation rates, and high biocompatibility. Despite the attractive characteristics, certain constraints associated with PLGA, in terms of its hydrophobicity and limited bioactivity, have led to the introduction of modification strategies that aimed to improve the biological performance of the polymer. Here, we summarize the features of the polymer and update views on progress of its applications as barrier membranes, bone grafts, and drug delivery carriers, which indicate that PLGA can be a good candidate material in the field of periodontal regenerative medicine.

Preparation and characterization of gadolinium-loaded PLGA particles surface modified with RGDS for the detection of thrombus

Thrombotic disease is a leading cause of death and disability worldwide. The development of magnetic resonance molecular imaging provides potential promise for early disease diagnosis. In this study, we explore the preparation and characterization of gadolinium (Gd)-loaded poly (lactic-co-glycolic acid) (PLGA) particles surface modified with the Arg-Gly-Asp-Ser (RGDS) peptide for the detection of thrombus. PLGA was employed as the carrier-delivery system, and a double emulsion solvent-evaporation method (water in oil in water) was used to prepare PLGA particles encapsulating the magnetic resonance contrast agent Gd diethylenetriaminepentaacetic acid (DTPA). To synthesize the Gd-PLGA/chitosan (CS)-RGDS particles, carbodiimide-mediated amide bond formation was used to graft the RGDS peptide to CS to form a CS-RGDS film that coated the surface of the PLGA particles. Blank PLGA, Gd-PLGA, and Gd-PLGA/CS particles were fabricated using the same water in oil in water method. Our results indicated that the RGDS peptide successfully coated the surface of the Gd-PLGA/CS-RGDS particles. The particles had a regular shape, smooth surface, relatively uniform size, and did not aggregate. The high electron density of the Gd-loaded particles and a translucent film around the particles coated with the CS and CS-RGDS films could be observed by transmission electron microscopy. In vitro experiments demonstrated that the Gd-PLGA/CS-RGDS particles could target thrombi and could be imaged using a clinical magnetic resonance scanner. Compared with the Gd-DTPA solution, the longitudinal relaxation time of the Gd-loaded particles was slightly longer, and as the Gd-load concentration increased, the longitudinal relaxation time values decreased. These results suggest the potential of the Gd-PLGA/CS-RGDS particles for the sensitive and specific detection of thrombus at the molecular level.

Formulation and optimization of mucoadhesive nanodrug delivery system of acyclovir

Acyclovir is an antiviral drug used for the treatment of herpes simplex virus infections, with an oral bioavailability of only 10-20% [limiting absorption in gastrointestinal tract to duodenum and jejunum] and half-life of about 3 h, and is soluble only at acidic pH (pKa 2.27). Mucoadhesive polymeric nanodrug delivery systems of acyclovir have been designed and optimized using 2(3) full factorial design. Poly (lactic-co-glycolic acid) (PLGA) (50:50) was used as the polymer along with polycarbophil (Noveon AA-1) as the mucoadhesive polymer and pluronic F68 as the stabilizer. From the preliminary trials, the constraints for independent variables X(1) (amount of PLGA), X(2) (amount of pluronic F68) and X(3) (amount of polycarbophil) have been fixed. The dependent variables that were selected for study were particle size (Y(1)), % drug entrapment (Y(2)) and % drug release in 12 h (Y(3)). The derived polynomial equations were verified by check point formulation. The application of factorial design gave a statistically systematic approach for the formulation and optimization of nanoparticles with the desired particle size, % drug release and high entrapment efficiency. Drug: Polymer ratio and concentration of stabilizer were found to influence the particle size and entrapment efficiency of acyclovir-loaded PLGA nanoparticles. The release was found to follow Fickian as well as non-Fickian diffusion mechanism with zero-order drug release for all batches. In vitro intestinal mucoadhesion of nanoparticles increased with increasing concentration of polycarbophil. These preliminary results indicate that acyclovir-loaded mucoadhesive PLGA nanoparticles could be effective in sustaining drug release for a prolonged period.

Practical preparation procedures for docetaxel-loaded nanoparticles using polylactic acid-co-glycolic acid

Background

Nanoparticles fabricated from the biodegradable and biocompatible polymer, polylactic-co-glycolic acid (PLGA), are the most intensively investigated polymers for drug delivery systems. The objective of this study was to explore fully the development of a PLGA nanoparticle drug delivery system for alternative preparation of a commercial formulation. In our nanoparticle fabrication, our purpose was to compare various preparation parameters.

Methods

Docetaxel-loaded PLGA nanoparticles were prepared by a single emulsion technique and solvent evaporation. The nanoparticles were characterized by various techniques, including scanning electron microscopy for surface morphology, dynamic light scattering for size and zeta potential, x-ray photoelectron spectroscopy for surface chemistry, and high-performance liquid chromatography for in vitro drug release kinetics. To obtain a smaller particle, 0.2% polyvinyl alcohol, 0.03% D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS), 2% Poloxamer 188, a five-minute sonication time, 130 W sonication power, evaporation with magnetic stirring, and centrifugation at 8000 rpm were selected. To increase encapsulation efficiency in the nanoparticles, certain factors were varied, ie, 2–5 minutes of sonication time, 70–130 W sonication power, and 5–25 mg drug loading.

Results

A five-minute sonication time, 130 W sonication power, and a 10 mg drug loading amount were selected. Under these conditions, the nanoparticles reached over 90% encapsulation efficiency. Release kinetics showed that 20.83%, 40.07%, and 51.5% of the docetaxel was released in 28 days from nanoparticles containing Poloxamer 188, TPGS, or polyvinyl alcohol, respectively. TPGS and Poloxamer 188 had slower release kinetics than polyvinyl alcohol. It was predicted that there was residual drug remaining on the surface from x-ray photoelectron spectroscopy.

Conclusion

Our research shows that the choice of surfactant is important for controlled release of docetaxel.

In situ forming polymeric drug delivery systems

In situ forming polymeric formulations are drug delivery systems that are in sol form before administration in the body, but once administered, undergo gelation in situ, to form a gel. The formation of gels depends on factors like temperature modulation, pH change, presence of ions and ultra violet irradiation, from which the drug gets released in a sustained and controlled manner. Various polymers that are used for the formulation of in situ gels include gellan gum, alginic acid, xyloglucan, pectin, chitosan, poly(DL-lactic acid), poly(DL-lactide-co-glycolide) and poly-caprolactone. The choice of solvents like water, dimethylsulphoxide, N-methyl pyrrolidone, triacetin and 2-pyrrolidone for these formulations depends on the solubility of polymer used. Mainly in situ gels are administered by oral, ocular, rectal, vaginal, injectable and intraperitoneal routes. The in situ gel forming polymeric formulations offer several advantages like sustained and prolonged action in comparison to conventional drug delivery systems. The article presents a detailed review of these types of polymeric systems, their evaluation, advancements and their commercial formulations. From a manufacturing point of view, the production of such devices is less complex and thus lowers the investment and manufacturing cost.