Preparation and characterization of silk fibroin/oligochitosan nanoparticles for siRNA delivery

Thermo-responsive composite nanoparticles based on hydroxybutyl chitosan oligosaccharide: Fabrication, stimulus release and cancer therapy

Designing thermo-responsive nanocarriers based on biopolymers is fascinating and challenging for cancer therapy. In this study, thermo-responsive composite nanoparticles (CNPs) were prepared using hydroxybutyl chitosan oligosaccharide (HBCOS) and sodium caseinate (SC) via electrostatic interactions and covalent crosslinking. The temperature-responsive behaviors of CNPs were induced by the breakage of hydrogen bonds and the shrinkage of chains in nanoparticles. The CNPs exhibited concentration-independent thermo-responsive behavior, non-adsorption aggregation, and non-hemolysis, suggesting excellent stability and thermo-sensitivity. The initial release rate and final amount of DOX released from CNPs at 42 °C were higher than that at 37 °C, showing a thermo-responsive release, which was also more prominent at lower pH. The release of DOX from CNPs followed first order kinetics based on Fickian diffusion. In vitro cytotoxicity assays confirmed the thermo-responsive antitumor activity of DOX-loaded CNPs as the HT-29 cell viability incubated with DOX-loaded CNPs at 42 °C was significantly lower than that at 37 °C. Cellular uptake experiments proved that DOX-loaded CNPs accumulated in the cytoplasm after being endocytosed and promoted DOX release by increasing environment temperature. This study generated stable thermo-sensitive CNPs based on biopolymers, which can be used as potential nanocarriers for the controlled release of anticancer drugs for cancer therapy.

Protein-based nanoparticles for therapeutic nucleic acid delivery

To realize the full potential of emerging nucleic acid therapies, there is a need for effective delivery agents to transport cargo to cells of interest. Protein materials exhibit several unique properties, including biodegradability, biocompatibility, ease of functionalization via recombinant and chemical modifications, among other features, which establish a promising basis for therapeutic nucleic acid delivery systems. In this review, we highlight progress made in the use of non-viral protein-based nanoparticles for nucleic acid delivery in vitro and in vivo, while elaborating on key physicochemical properties that have enabled the use of these materials for nanoparticle formulation and drug delivery. To conclude, we comment on the prospects and unresolved challenges associated with the translation of protein-based nucleic acid delivery systems for therapeutic applications.

Development of nanostructured formulation from naringenin and silk fibroin and application for inhibition of lipoxygenase (LOX)

A simple low-energy method was used to obtain polymeric nanoparticles containing silk fibroin (SF), fatty butyl esters (oily phase) and the flavonoid naringenin. Experimental planning (Box-Behnken) was applied to investigate the optimal conditions for three factors (variation of the concentrations of SF, naringenin and fatty butyl ester) at three levels, with evaluation of particle size, polydispersity index (PDI) and zeta potential (ZP) as responses. The results showed that the polymeric particle was formed with sizes of 179.6 to 633.9 nm, PDI of 0.33 to 0.77 and ZP of -60.4 to -38.8 mV. The best responses under the optimized conditions (Nari-SF 9 and 15) were characterized through transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR), visible ultraviolet (UV-vis) and fluorescence, which confirmed that coated nanoparticles had been obtained. It was shown that the nanoformulation had excellent stability, the bioavailability of naringenin had been improved through use of the biopolymer and high inhibition of the enzyme lipoxygenase had been achieved in vitro.

Allotropy of selenium nanoparticles: Colourful transition, synthesis, and biotechnological applications

Elemental selenium (Se⁰ ) nanomaterials undergo allotropic transition from thermodynamically-unstable to more stable phases. This process is significantly different when Se⁰ nanoparticles (NPs) are produced via physico-chemical and biological pathways. While the allotropic transition of physico-chemically synthesized Se⁰ is fast (minutes to hours), the biogenic Se⁰ takes months to complete. The biopolymer layer covering biogenic Se⁰ NPs might be the main factor controlling this retardation, but this still remains an open question. Phylogenetically-diverse bacteria reduce selenium oxyanions to red amorphous Se⁰ allotrope, which has low market value. Then, red Se⁰ undergoes allotropic transition to trigonal (metallic grey) allotrope, the end product having important industrial applications (e.g. semiconductors, alloys). Is it not yet clear whether biogenic Se⁰ presents any biological function, or it is mainly a detoxification and respiratory by-product. The better understanding of this transition would benefit the recovery of Se⁰ NPs from secondary resources and its targeted utilization with respect to each allotropic stage. This review article presents and critically discusses the main physico-chemical methods and biosynthetic pathways of Se⁰ (bio)mineralization. In addition, the article proposes a conceptual model for the resource recovery potential of trigonal selenium nanomaterials in the context of circular economy.

Enhanced osteogenic effect in reduced BMP-2 doses with siNoggin transfected pre-osteoblasts in 3D silk scaffolds

Bone morphogenetic proteins (BMPs), especially BMP-2, are being increasingly used in bone tissue engineering due to its osteo-inductive effects. Although recombinant human BMP-2 (rhBMP-2) was approved by Food and Drug Administration (FDA) to use for bone repair, its high doses cause undesired side effects. In order to reduce the BMP-2 dose for enhanced osteogenic differentiation, in this study we decided to suppress the synthesis of Noggin protein, the primary antagonist of BMP-2, on the MC3T3-E1 cells using Noggin targeted small interfering RNA (siRNA). Unlike other studies, Noggin siRNA (siNoggin) transfected cells were seeded on silk scaffolds, and osteogenic differentiation was investigated for a long-term period (21 days) with MTT, qPCR, SEM/EDS, and histological analysis. Besides, siNoggin transfected MC3T3-E1 cells were evaluated as a new cell source for tissue engineering studies. It was determined that Nog gene expression was suppressed in the siNoggin group and Ocn gene expression increased 5-fold compared to the control group (*p < 0.05). The osteogenic effect of BMP-2 was clearly observed in siNoggin transfected cells. According to the SEM/EDS analysis, the siNoggin group has mineral structures clustered on cells, which contain intense Ca and P elements. Histological staining showed that the siNoggin group has a more intense mineralized area than that of the control group. In conclusion, this study indicated that Noggin silencing by siRNA induces osteogenic differentiation in reduced BMP-2 doses for scaffold-based bone regeneration. This non-gene integration strategy has as a safe therapeutic potential to enhance tissue regeneration.

Systemic and Local Silk-Based Drug Delivery Systems for Cancer Therapy

For years, surgery, radiotherapy, and chemotherapy have been the gold standards to treat cancer, although continuing research has sought a more effective approach. While advances can be seen in the development of anticancer drugs, the tools that can improve their delivery remain a challenge. As anticancer drugs can affect the entire body, the control of their distribution is desirable to prevent systemic toxicity. The application of a suitable drug delivery platform may resolve this problem. Among other materials, silks offer many advantageous properties, including biodegradability, biocompatibility, and the possibility of obtaining a variety of morphological structures. These characteristics allow the exploration of silk for biomedical applications and as a platform for drug delivery. We have reviewed silk structures that can be used for local and systemic drug delivery for use in cancer therapy. After a short description of the most studied silks, we discuss the advantages of using silk for drug delivery. The tables summarize the descriptions of silk structures for the local and systemic transport of anticancer drugs. The most popular techniques for silk particle preparation are presented. Further prospects for using silk as a drug carrier are considered. The application of various silk biomaterials can improve cancer treatment by the controllable delivery of chemotherapeutics, immunotherapeutics, photosensitizers, hormones, nucleotherapeutics, targeted therapeutics (e.g., kinase inhibitors), and inorganic nanoparticles, among others.

Combination Therapy of Breast Cancer by Codelivery of Doxorubicin and Survivin siRNA Using Polyethylenimine Modified Silk Fibroin Nanoparticles

Here, polyethylenimine (PEI) modified silk fibroin nanoparticles (SFNPs) were prepared for codelivery of doxorubicin (DOX) and survivin siRNA. The prepared NPs were characterized in terms of stability and structural, functional, and physicochemical properties. Moreover, the ability of the conjugate to escape from the endosome and cellular uptake were assessed. Afterward, the in vivo therapeutic efficacy was analyzed in the mice model. The siRNA loaded PEI-SFNPs showed acceptable size, zeta potential, and stability in serum. It also effectively induced apoptosis in the 4T1 mouse mammary tumor cell line. Cellular uptake and endosomal escape analyses confirmed that PEI-SFNPs containing siRNA could escape from the endosome and accumulate in the cytoplasm of 4T1 cells. Real time-PCR indicated the significant decrease in the expression of survivin mRNA in the 4T1 cell line 48 h postincubation with siRNA loaded PEI-SFNPs. In vivo biodistribution of PEI-SFNPs confirmed higher accumulation of SFNPs in the tumor site compared with other organs. The codelivery systems remarkably reduced the growth rate of breast tumor in the mice model without any obvious weight lost. Histopathological and tunnel staining exhibited more apoptotic tumor cells in the group containing both DOX and survivin siRNA. Tumorigenic breast tissue resected from the animals after treatment with siRNA also exhibited significant suppression of survivin gene. In conclusion, the prepared drug delivery system had an acceptable potential in tumor removal, apoptosis induction in cancer cells, and therapeutic efficacy. Thus, it would be a good candidate for breast cancer therapy.

Preparation of AuNPs/SF Nanofibers and Its Ability to Inhibit Tumor Growth in Breast Cancer-Bearing Animal Models

Silk fibroin was used as a stabilizer for gold nanoparticles, and a direct silk fibroin-gold nanoparticle composite system was prepared by a direct compounding method in this paper. The stability of Au NPs/SF in phosphate buffer solution with different pH and KCl concentration was studied. The Au NPs/SF system was characterized by UV-visible light spectrum, transmission electron microscope and infrared spectrum. The silk fibroin-gold nanoparticle composite system was prepared by in situ reduction of chloroauric acid with silk fibroin, according to the change of solution color and the change of ultraviolet absorption peak. The effects of exogenous factors on the stability of the silk fibroin-gold nanoparticle in situ composite system were initially discussed, and its inhibition in breast cancer-bearing animal models was studied. In vivo experiments show that in situ injection of Au NPs/SF nanofibers and treatment with light can effectively control tumor growth. Compared with monodisperse gold nanoparticles, silk fibroin-gold nanoparticles can kill tumor cells and inhibit tumor tissue growth more effectively.

Fibroin nanoparticles: a promising drug delivery system

Fibroin is a dominant silk protein that possesses ideal properties as a biomaterial for drug delivery. Recently, the development of fibroin nanoparticles (FNPs) for various biomedical applications has been extensively studied. Due to their versatility and chemical modifiability, FNPs can encapsulate different types of therapeutic compounds, including small and big molecules, proteins, enzymes, vaccines, and genetic materials. Moreover, FNPs are able to be administered both parenterally and non-parenterally. This review summaries basic information on the silk and fibroin origin and characteristics, followed by the up-to-date data on the FNPs preparation and characterization methods. In addition, their medical applications as a drug delivery system are in-depth explored based on several administrative routes of parenteral, oral, transdermal, ocular, orthopedic, and respiratory. Finally, the challenges and suggested solutions, as well as the future outlooks of these systems are discussed.

Silk Particles as Carriers of Therapeutic Molecules for Cancer Treatment

Although progress is observed in cancer treatment, this disease continues to be the second leading cause of death worldwide. The current understanding of cancer indicates that treating cancer should not be limited to killing cancer cells alone, but that the target is the complex tumor microenvironment (TME). The application of nanoparticle-based drug delivery systems (DDS) can not only target cancer cells and TME, but also simultaneously resolve the severe side effects of various cancer treatment approaches, leading to more effective, precise, and less invasive therapy. Nanoparticles based on proteins derived from silkworms' cocoons (like silk fibroin and sericins) and silk proteins from spiders (spidroins) are intensively explored not only in the oncology field. This natural-derived material offer biocompatibility, biodegradability, and simplicity of preparation methods. The protein-based material can be tailored for size, stability, drug loading/release kinetics, and functionalized with targeting ligands. This review summarizes the current status of drug delivery systems' development based on proteins derived from silk fibroin, sericins, and spidroins, which application is focused on systemic cancer treatment. The nanoparticles that deliver chemotherapeutics, nucleic acid-based therapeutics, natural-derived agents, therapeutic proteins or peptides, inorganic compounds, as well as photosensitive molecules, are introduced.

Protein-Based Nanoparticles as Drug Delivery Systems

Nanoparticles have been extensively used as carriers for the delivery of chemicals and biomolecular drugs, such as anticancer drugs and therapeutic proteins. Natural biomolecules, such as proteins, are an attractive alternative to synthetic polymers commonly used in nanoparticle formulation because of their safety. In general, protein nanoparticles offer many advantages, such as biocompatibility and biodegradability. Moreover, the preparation of protein nanoparticles and the corresponding encapsulation process involved mild conditions without the use of toxic chemicals or organic solvents. Protein nanoparticles can be generated using proteins, such as fibroins, albumin, gelatin, gliadine, legumin, 30Kc19, lipoprotein, and ferritin proteins, and are prepared through emulsion, electrospray, and desolvation methods. This review introduces the proteins used and methods used in generating protein nanoparticles and compares the corresponding advantages and disadvantages of each.

All-Trans Retinoic Acid Grafted Poly Beta-Amino Ester Nanoparticles: A Novel Anti-angiogenic Drug Delivery System

Purpose: Developing chemotherapy with nanoplatforms offers a promising strategy for effective cancer treatment. In the present study, we propose a novel all-trans retinoic acid (ATRA) grafted poly beta-amino ester (PBAE) copolymer for preparing nanoparticles (NPs). Methods: ATRA grafted PBAE (ATRA-g-PBAE) copolymer was synthesized by grafting ATRA to PBAE; it was characterized by proton nuclear magnetic resonance, Fourier transform infrared, and thermogravimetric analysis. ATRA-g-PBAE NPs were prepared by the solvent displacement method. Design-Expert software was employed to optimize size of NPs. The morphology was evaluated by transmission electron microscope, and ultraviolet-visible spectroscopy was applied for drug release. Cytotoxicity was evaluated toward HUVEC cell line, and the 3D collagencytodex model was used to evaluate anti-angiogenic property of PBAE, ATRA, and NPs. Results: The optimum size of the NPs was 139.4 ± 1.41 nm. After 21 days, 66.09% ± 1.39 and 42.14% ± 1.07 of ATRA were released from NPs at pH 5.8 and 7.4, respectively. Cell culture studies demonstrated antiangiogenic effects of ATRA-g-PBAE NPs. Anti-angiogenesis IC50 was 0.007 mg/mL for NPs (equal to 0.002 mg/mL of ATRA) and 0.005 mg/mL for free ATRA. Conclusion: This study proposes the ATRA-g-PBAE NPs with inherent anti-angiogenic effects as promising carrier for anticancer drugs with purpose of dual drug delivery.

Preparation and Characterization of Silk Fibroin Nanoparticles as a Potential Drug Delivery System for 5-Fluorouracil

Purpose: The aim of this study is to prepare 5-fluorouracil (5-FU) loaded silk fibroin nanoparticles (SFNPs) and to achieve a controlled release delivery system with the high loading capacity. Methods: SFNPs with 1:1, 1:3, and 1:10 ratios of 5-FU to silk fibroin were prepared. SFNPs were characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) analysis, Scanning electron microscope (SEM), and Transmission electron microscope (TEM). Loading efficiency, in vitro release, and cell viability were studied for optimal SFNPs. Results: The ratio of 1:1 was optimal formulation with the size and polydispersity index (PDI) of 221.03 nm and 0.093 before freeze drying, and 286.7 nm and 0.154 after freeze drying by lactose, respectively. The loading efficiency and loading content of this ratio were 52.32% and 34.35%, respectively. FT-IR and XRD analysis indicated the conformational change (from random coil to β-sheet) in the structure of nanoparticles by increasing amount of the drug, which caused the smaller size, the higher loading efficiency, and the slower release pattern. The drugloaded nanoparticles reached to the half maximal inhibitory concentration (IC50) that were comparable with free drug on MCF7 (human breast cancer) cell line. Conclusion: This study was planned to achieve a promising controlled release drug delivery system for carrying 5-FU, as a potent anticancer drug. SFNPs were found proper candidates for delivery of a hydrophilic drug such as 5-FU.

Alphastatin-Loaded Chitosan Nanoparticle Preparation and Its Antiangiogenic Effect on Lung Carcinoma

Alphastatin is a 24-amino acid peptide and can suppress tumor angiogenesis by inhibiting both the migration and tubule formation of vascular endothelial cells. However, the anticancer effect of Alphastatin is limited due to the short half-life and degradation in the body. In this study, Alphastatin-loaded chitosan nanoparticles (AsCs NPs) were prepared with an initial concentration of 2 mg/ml for chitosan and 1 mg/ml for Alphastatin. AsCs NPs presented the encapsulation efficiency of 32.4%, the mean particle size of 387.4 nm, the polydispersity index of 0.223, and the zeta potential of +28.1 mV. AsCs NPs have a sustained release for 6 days and were stable in serum for at least 24 hours. And the NPs could preserve the integrity of encapsulated Alphastatin and released Alphastatin for 24 hours. In a subcutaneous LA975 lung carcinoma xenograft T739 mouse model, AsCs NPs significantly inhibited the tumor growth, tumor volume, and microvessel density (MVD), and the antitumor effect was even stronger than that of Alphastatin. In addition, the VEGF-induced tube formation of HUVEC could be inhibited by AsCs NPs in vitro and the serum containing AsCs NPs, and the protein level of SphK1 in HUVEC was also decreased by AsCs NPs, suggesting an inhibitory effect of AsCs NPs on the SphK1-S1P signaling pathway. Furthermore, hemolysis assay showed a safety on blood compatibility of AsCs NPs. Our study indicated that AsCs NPs inhibited the SphK1-S1P signaling pathway and enhanced the antiangiogenic effect of Alphastatin both in vitro and in vivo.

Exploring the Structural Transformation Mechanism of Chinese and Thailand Silk Fibroin Fibers and Formic-Acid Fabricated Silk Films

Silk fibroin (SF) is a protein polymer derived from insects, which has unique mechanical properties and tunable biodegradation rate due to its variable structures. Here, the variability of structural, thermal, and mechanical properties of two domesticated silk films (Chinese and Thailand B. Mori) regenerated from formic acid solution, as well as their original fibers, were compared and investigated using dynamic mechanical analysis (DMA) and Fourier transform infrared spectrometry (FTIR). Four relaxation events appeared clearly during the temperature region of 25 °C to 280 °C in DMA curves, and their disorder degree (fdis) and glass transition temperature (Tg) were predicted using Group Interaction Modeling (GIM). Compared with Thai (Thailand) regenerated silks, Chin (Chinese) silks possess a lower Tg, higher fdis, and better elasticity and mechanical strength. As the calcium chloride content in the initial processing solvent increases (1%⁻6%), the Tg of the final SF samples gradually decrease, while their fdis increase. Besides, SF with more non-crystalline structures shows high plasticity. Two α- relaxations in the glass transition region of tan δ curve were identified due to the structural transition of silk protein. These findings provide a new perspective for the design of advanced protein biomaterials with different secondary structures, and facilitate a comprehensive understanding of the structure-property relationship of various biopolymers in the future.

DNA preservation in silk

The structure of DNA is susceptible to alterations at high temperature and on changing pH, irradiation and exposure to DNase. Options to protect and preserve DNA during storage are important for applications in genetic diagnosis, identity authentication, drug development and bioresearch. In the present study, the stability of total DNA purified from human dermal fibroblast cells, as well as that of plasmid DNA, was studied in silk protein materials. The DNA/silk mixtures were stabilized on filter paper (silk/DNA + filter) or filter paper pre-coated with silk and treated with methanol (silk/DNA + PT-filter) as a route to practical utility. After air-drying and water extraction, 50-70% of the DNA and silk could be retrieved and showed a single band on electrophoretic gels. 6% silk/DNA + PT-filter samples provided improved stability in comparison with 3% silk/DNA + filter samples and DNA + filter samples for DNA preservation, with ∼40% of the band intensity remaining at 37 °C after 40 days and ∼10% after exposure to UV light for 10 hours. Quantitative analysis using the PicoGreen assay confirmed the results. The use of Tris/borate/EDTA (TBE) buffer enhanced the preservation and/or extraction of the DNA. The DNA extracted after storage maintained integrity and function based on serving as a functional template for PCR amplification of the gene for zinc finger protein 750 (ZNF750) and for transgene expression of red fluorescence protein (dsRed) in HEK293 cells. The high molecular weight and high content of a crystalline beta-sheet structure formed on the coated surfaces likely accounted for the preservation effects observed for the silk/DNA + PT-filter samples. Although similar preservation effects were also obtained for lyophilized silk/DNA samples, the rapid and simple processing available with the silk-DNA-filter membrane system makes it appealing for future applications.

Mechanistic In vitro Evaluation of Prosopis farcta Roots Potential as an Antidiabetic Folk Medicinal Plant

OBJECTIVE

Prosopis farcta has been used as a traditional herbal medicine for treating Diabetes mellitus. The aim of this study is to investigate the antidiabetic mechanisms of infusion (INF) extract of P. farcta and discovering the active extract for the first time.

MATERIALS AND METHODS

Six different extracts of P. farcta were prepared using five different solvents (ethanol, n-hexane, acetone, ethanol:water (1:1 v/v), and water). Cytotoxicity and cell proliferation assays were performed on mouse pancreatic β-cells (β-TC3) using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium method. The effects of P. farcta on glucose metabolism (in a hepatocellular carcinoma cell line [HepG2]) and glucose diffusion across a dialysis membrane (as a model of cellular glucose absorption) were evaluated. The protective effect of various P. farcta extracts on cytotoxicity, mitochondrial membrane potential (MMP), and streptozotocin (STZ)-induced apoptosis in β-TC3 cells was investigated.

RESULTS

Cytotoxicity study indicated that extracts were safe on β-TC3 and HepG2 (≤0.5 mg/ml). INF protected β-TC3 cells from apoptosis induced by STZ and improved cell viability for 20% and significantly decrease depolarization of MMP (P < 0.005). The results showed that INF inhabited breaking/streaking the DNA. Proliferation study showed no significant increase in the number of cells either at single or multiple doses. In moderate hyperglycemia (11.1 mmol/l), a significant glucose-lowering effect was observed but glucose diffusion was not the probable mechanism of extracts antidiabetic effect. In conclusion, only INF, the traditionally used extract, has an antidiabetic potential by attenuating the death and apoptosis induced by STZ in β-TC3 cells and increase glucose consumption.

CONCLUSION

The present study demonstrates that only INF extract have an antidiabetic potential by attenuating the death and apoptosis induced by STZ in β-TC3 cells and increase glucose consumption.

SUMMARY

Six different extracts from P. farcta were prepared using five different solvents [ethanol, n-hexane, acetone, ethanol: water (1:1 v/v), and water]The protective effect of various P. farcta extracts on cytotoxicity, mitochondrial membrane potential (MMP), and Streptozotocin-induced apoptosis in β-TC3 cells were investigated.Infusion has an antidiabetic potential by attenuating the death and apoptosis induced by STZ in β-TC3 cells and increase glucose consumptionThe effect of infusion extract on glucose consumption in hepatocellular carcinoma cell line cells (a) and effect of infusion extract on glucose consumption in hepatocellular carcinoma cell line cells adjusted by optical density MTT (b). Significance was calculated by analysis of variance (*P ≤ 0.05). MTT: 3 (4,5 dimethylthiazol 2 yl) 2,5 diphenyltetrazolium. Abbreviations used: AC: Acetone extract; ANOVA: Analysis of variance; BSA: Bovine serum albumin; β-TC3: Mouse pancreatic β-cells; DMEM: Dulbecco modified Eagle medium; DMSO: Dimethyl sulfoxide; ETH: Ethyl acetate extract; FBS: Fetal bovine serum; HDETH: Hydroethanolic extract; HepG2: Hepatocellular carcinoma cell line; HEX: Hexane extract; INF: Infusion; KUMS: Kermanshah University of Medical Sciences; MMP: Mitochondrial membrane potential; MTT: 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium; NaCl: Natrium chloride; OD: Optical density; spp: Species; STZ: Streptozotocin; Tag: T-antigen; USA: United States of America.

Silk Materials Functionalized via Genetic Engineering for Biomedical Applications

The great mechanical properties, biocompatibility and biodegradability of silk-based materials make them applicable to the biomedical field. Genetic engineering enables the construction of synthetic equivalents of natural silks. Knowledge about the relationship between the structure and function of silk proteins enables the design of bioengineered silks that can serve as the foundation of new biomaterials. Furthermore, in order to better address the needs of modern biomedicine, genetic engineering can be used to obtain silk-based materials with new functionalities. Sequences encoding new peptides or domains can be added to the sequences encoding the silk proteins. The expression of one cDNA fragment indicates that each silk molecule is related to a functional fragment. This review summarizes the proposed genetic functionalization of silk-based materials that can be potentially useful for biomedical applications.

Preparation of 5-fluorouracil-loaded chitosan nanoparticles and study of the sustained release in vitro and in vivo

The sustained-release properties of the biodegradable nano-drug delivery systems were used to improve the residence time of the chemotherapeutic agent in the body. These drug delivery systems were widely used to deliver chemotherapeutic drugs. The 5-fluorouracil loaded chitosan nanoparticles prepared in this paper have the above advantage. Here, we found that when the mass ratio of 5-fluorouracil and chitosan was 1:1, the maximum drug loading of nanoparticles was 20.13 ± 0.007%, the encapsulation efficiency was 44.28 ± 1.69%, the particle size was 283.9 ± 5.25 nm and the zeta potential was 45.3 ± 3.23 mV. The prepared nanoparticles had both burst-release and sustained-release phases in vitro release studies. In addition, the inhibitory effect of the prepared nanoparticles on gastric cancer SGC-7901 cells was similar to that of 5-fluorouracil injection, and the blank vector had no obvious inhibitory effect on SGC-7901 cells. In the pharmacokinetic study of rats in vivo, we found that AUC _(0−t), MRT _(0−t) and t_1/2z of nanoparticles were significantly increased in vivo compared with 5-fluorouracil solution, indicating that the prepared nanoparticles can play a role in sustained-release.

Preparation and Characterization of Pistacia khinjuk Gum Nanoparticles Using Response Surface Method: Evaluation of Its Anti-Bacterial Performance and Cytotoxicity

Purpose: This study aims to prepare a novel, natural nanoparticle (NP) as a drug carrier, which also has inherent therapeutic effects.

Methods: Pistacia khinjuk gum NPs were prepared and Response surface methodology (RSM) was used for statistical analysis of data and optimizing the size of NPs.

Results: NPs were in the range of 75.85–241.3 nm. The optimization study was carried out, and an optimized size (70.86nm) was obtained using DMSO as a solvent. The volume of the organic phase was 111.25µl, and the concentration of gum was 1% w/v. The cell viability assay was performed on the pure gum and NPs toward β-TC₃, MCF7, and HT29 cell lines. It was observed that NPs have higher cytotoxic activity in comparison with pure gum, and that the IC₅₀value was achieved at 1% of NPs in β-TC3 cells. The obtained NPs demonstrated antibacterial activity against two bacterial strains (Pseudomonas aeruginosa and Staphylococcus aureus).

Conclusion: Altogether, according to the obtained results, these NPs with inherent cytotoxicity and antibacterial activity are an attractive carrier for drug delivery.

Cytotoxic effect of zinc oxide nanoparticles on murine photoreceptor cells via potassium channel block and Na+ /K+ -ATPase inhibition

OBJECTIVE

Zinc oxide (ZnO) nanoparticles can exhibit toxicity towards organisms and oxidative stress is often hypothesized to be one of the most important factors. Nevertheless, the detailed mechanism of toxicity-induced by ZnO nanoparticles has not been completely addressed. The present study aimed to investigate the toxic effects of ZnO nanoparticles on the expression and activity of Na⁺ /K⁺ -ATPase and on potassium channel block.

MATERIALS AND METHODS

In the present study, we explored the cytotoxic effect of ZnO nanoparticles on murine photoreceptor cells using lactate dehydrogenase (LDH) release assay, reactive oxygen species (ROS) determination, mitochondrial membrane potential (Δφm) measurement, delayed rectifier potassium current recordings and Na⁺ /K⁺ -ATPase expression and activity monitoring.

RESULTS

The results indicated that ZnO nanoparticles could increase the LDH release in medium, aggravate the ROS level within cells, collapse the Δφm, block the delayed rectifier potassium current, and attenuate the expressions of Na⁺ /K⁺ -ATPase at both mRNA and protein levels and its activity, and thus exert cytotoxic effects on murine photoreceptor cells, finally damaging target cells.

CONCLUSION

Our findings will facilitate the understanding of the mechanism involved in ZnO nanoparticle-induced cytotoxicity in murine photoreceptor cells via potassium channel block and Na⁺ /K⁺ -ATPase inhibition.

Anti-EphA10 antibody-conjugated pH-sensitive liposomes for specific intracellular delivery of siRNA

Therapeutic delivery of small interfering RNA (siRNA) is a major challenge that limits its potential clinical application. Here, a pH-sensitive cholesterol–Schiff base–polyethylene glycol (Chol–SIB–PEG)-modified cationic liposome–siRNA complex, conjugated with the recombinant humanized anti-EphA10 antibody (Eph), was developed as an efficient nonviral siRNA delivery system. Chol–SIB–PEG was successfully synthesized and confirmed with FTIR and ¹H-NMR. An Eph–PEG–SIB–Chol-modified liposome–siRNA complex (EPSLR) was prepared and characterized by size, zeta potential, gel retardation, and encapsulation efficiency. Electrophoresis results showed that EPSLR was resistant to heparin replacement and protected siRNA from fetal bovine serum digestion. EPSLR exhibited only minor cytotoxicity in MCF-7/ADR cells. The results of flow cytometry and confocal laser scanning microscopy suggested that EPSLR enhanced siRNA transfection in MCF-7/ADR cells. Intracellular distribution experiment revealed that EPSLR could escape from the endo-lysosomal organelle and release siRNA into cytoplasm at 4 hours posttransfection. Western blot experiment demonstrated that EPSLR was able to significantly reduce the levels of MDR1 protein in MCF-7/ADR cells. The in vivo study of DIR-labeled complexes in mice bearing MCF-7/ADR tumor indicated that EPSLR could reach the tumor site rather than other organs more effectively. All these results demonstrate that EPSLR has much potential for effective siRNA delivery and may facilitate its therapeutic application.