Development of biocompatible electrostatic-repulsive microparticles for local tumor treatment

In this study, we reported pH-responsive microparticles consisting of poly(D,L-lactide-co-glycolide) (PLGA), aminated hyaluronic acid (aHA) conjugated with 2,3-dimethylmaleic anhydride (DMA, as a pH-responsive cleavable molecule) (aHA-DMA), and doxorubicin (DOX, as an antitumor drug) for local tumor treatment. The DOX-loaded microparticles, denoted as PLGA(aHA-DMA)/DOX MPs, were fabricated using the W₁/O/W₂ multi-emulsification method. These PLGA(aHA-DMA)/DOX MPs (~10 μm in diameter) accelerated the rate of DOX release at pH 6.8 due to the acidic pH-responsive cleavage of the DMA moieties followed by electrostatic-repulsion between aHA and DOX. This event caused the structural destabilization and collapse of the MPs, leading to the rapid release of DOX. Consequently, the PLGA(aHA-DMA)/DOX MPs resulted in significant inhibition of tumor growth, demonstrating their ability for acidic tumor-specific treatment.     

A pH-responsive ultrathin Cu-based nanoplatform for specific photothermal and chemodynamic synergistic therapy

Noninvasive tumor therapy requires a new generation of bionanomaterials towards sensitive response to the unique tumor microenvironment to achieve accurate and effective treatment. Herein, we have developed a tumor therapy nanoplatform by immobilizing natural glucose oxidase (GOD) onto Cu-based layered double hydroxide (CuFe-LDH) nanosheets, which for the first time integrates acid-enhanced photothermal therapy (PTT), and pH-responsive and heat-facilitated chemodynamic therapy (CDT) simultaneously. As demonstrated by EXAFS and HRTEM, CuFe-LDH nanosheets possess a considerable number of defects caused by different acid conditions, resulting in a significantly acid-enhanced photothermal conversion efficiency (83.2% at pH 5.4 vs. 46.0% at pH 7.4). Moreover, GOD/CuFe-LDH nanosheets can convert a cascade of glucose into hydroxyl radicals (˙OH) under tumor acid conditions, which is validated by a high maximum velocity (V_max = 2.00 × 10⁻⁷ M) and low Michaelis–Menten constant (K_M = 12.01 mM). With the combination of PTT and CDT, the tumor tissue in vivo is almost eliminated with low-dose drug injection (1 mg kg⁻¹). Therefore, this novel pH-responsive Cu-based nanoplatform holds great promise in tumor-specific CDT/PTT synergistic therapy.

A pH-responsive multifunctional nanosystem was synthesized by loading glucose oxidase (GOD) onto CuFe-layered double hydroxide (LDH) nanosheets, which exhibited synchronous acid-enhanced/responsive photothermal and chemodynamic synergistic therapy.     

Optical Properties of Doxorubicin Hydrochloride Load and Release on Silica Nanoparticle Platform

Silica nanoparticles (SiO₂ NPs) synthesized by the Stober method were used as drug delivery vehicles. Doxorubicin hydrochloride (DOX·HCl) is a chemo-drug absorbed onto the SiO₂ NPs surfaces. The DOX·HCl loading onto and release from the SiO₂ NPs was monitored via UV-VIS and fluorescence spectra. Alternatively, the zeta potential was also used to monitor and evaluate the DOX·HCl loading process. The results showed that nearly 98% of DOX·HCl was effectively loaded onto the SiO₂ NPs’ surfaces by electrostatic interaction. The pH-dependence of the process wherein DOX·HCl release out of DOX·HCl-SiO₂ NPs was investigated as well. For comparison, both the free DOX·HCl molecules and DOX·HCl-SiO₂ NPs were used as the labels for cultured cancer cells. Confocal laser scanning microscopy images showed that the DOX·HCl-SiO₂ NPs were better delivered to cancer cells which are more acidic than healthy cells. We propose that engineered DOX·HCl-SiO₂ systems are good candidates for drug delivery and clinical applications.     

Anti-Inflammatory CeO2 Nanoparticles Prevented Cytotoxicity Due to Exogenous Nitric Oxide Donors via Induction Rather Than Inhibition of Superoxide/Nitric Oxide in HUVE Cells

The mechanism behind the cytoprotective potential of cerium oxide nanoparticles (CeO₂ NPs) against cytotoxic nitric oxide (NO) donors and H₂O₂ is still not clear. Synthesized and characterized CeO₂ NPs significantly ameliorated the lipopolysaccharide (LPS)-induced cytokines IL-1β and TNF-α. The main goal of this study was to determine the capacities of NPs regarding signaling effects that could have occurred due to reactive oxygen species (ROS) and/or NO, since NP-induced ROS/NO did not lead to toxicity in HUVE cells. Concentrations that induced 50% cell death (i.e., IC50s) of two NO donors (DETA-NO; 1250 ± 110 µM and sodium nitroprusside (SNP); 950 ± 89 µM) along with the IC50 of H₂O₂ (120 ± 7 µM) were utilized to evaluate cytoprotective potential and its underlying mechanism. We determined total ROS (as a collective marker of hydrogen peroxide, superoxide radical (O₂^•−), hydroxyl radical, etc.) by DCFH-DA and used a O₂^•− specific probe DHE to decipher prominent ROS. The findings revealed that signaling effects mediated mainly by O₂^•− and/or NO are responsible for the amelioration of toxicity by CeO₂ NPs at 100 µg/mL. The unaltered effect on mitochondrial membrane potential (MMP) due to NP exposure and, again, CeO₂ NPs-mediated recovery in the loss of MMP due to exogenous NO donors and H₂O₂ suggested that NP-mediated O₂^•− production might be extra-mitochondrial. Data on activated glutathione reductase (GR) and unaffected glutathione peroxidase (GPx) activities partially explain the mechanism behind the NP-induced gain in GSH and persistent cytoplasmic ROS. The promoted antioxidant capacity due to non-cytotoxic ROS and/or NO production, rather than inhibition, by CeO₂ NP treatment may allow cells to develop the capacity to tolerate exogenously induced toxicity.     

Rational design of a “dual lock-and-key” supramolecular photosensitizer based on aromatic nucleophilic substitution for specific and enhanced photodynamic therapy

Photosensitizing agents are essential for precise and efficient photodynamic therapy (PDT). However, most of the conventional photosensitizers still suffer from limitations such as aggregation-caused quenching (ACQ) in physiological environments and toxic side-effects on normal tissues during treatment, leading to reduced therapeutic efficacy. Thus, integrating excellent photophysical properties and accurate carcinoma selectivity in a photosensitizer system remains highly desired. Herein, a “dual lock-and-key” supramolecular photosensitizer BIBCl–PAE NPs for specific and enhanced cancer therapy is reported. BIBCl–PAE NPs are constructed by encapsulating a rationally designed glutathione (GSH)-activatable photosensitizer BIBCl in a pH-responsive diblock copolymer. In normal tissues, BIBCl is “locked” in the hydrophobic core of the polymeric micelles due to ACQ. Under the “dual key” activation of low pH and high levels of GSH in a tumor microenvironment, the disassembly of micelles facilitates the reaction of BIBCl with GSH to release water-soluble BIBSG with ideal biocompatibility, enabling the highly efficient PDT. Moreover, benefiting from the Förster resonance energy transfer effect of BIBSG, improved light harvesting ability and ¹O₂ production are achieved. In vitro and vivo experiments have demonstrated that BIBCl–PAE NPs are effective in targeting and inhibiting carcinoma. BIBCl–PAE NPs show superior anticancer efficiency relative to non-activatable controls.

The “dual lock-and-key” supramolecular photosensitizers enable specific and enhanced photodynamic therapy (PDT).     

Hypocrellin B doped and pH-responsive silica nanoparticles for photodynamic therapy

pH-responsive ¹O₂ photosensitizing systems may serve as selective photodynamic therapy (PDT) agents by targeting the acidic interstitial fluid of many kinds of tumors. In this work, a natural and clinically used photosensitizer (Hypocrellin B, HB) and a pH indicator (Bromocresol Purple, BCP) were co-encapsulated in organically modified silica nanoparticles. BCP successfully regulated the ¹O₂ generation efficiency of HB through the “inner filter” effect, which shows much stronger ¹O₂ generation ability in an acidic than in a basic environment. In vitro experiments also demonstrated that HB-doped nanoparticles are effective in killing tumor cells by PDT.

     

Periodic Mesoporous Organosilica Nanoparticles for CO2 Adsorption at Standard Temperature and Pressure

(1) Background: Due to human activities, greenhouse gas (GHG) concentrations in the atmosphere are constantly rising, causing the greenhouse effect. Among GHGs, carbon dioxide (CO₂) is responsible for about two-thirds of the total energy imbalance which is the origin of the increase in the Earth’s temperature. (2) Methods: In this field, we describe the development of periodic mesoporous organosilica nanoparticles (PMO NPs) used to capture and store CO₂ present in the atmosphere. Several types of PMO NP (bis(triethoxysilyl)ethane (BTEE) as matrix, co-condensed with trialkoxysilylated aminopyridine (py) and trialkoxysilylated bipyridine (Etbipy and iPrbipy)) were synthesized by means of the sol-gel procedure, then characterized with different techniques (DLS, TEM, FTIR, BET). A systematic evaluation of CO₂ adsorption was carried out at 298 K and 273 K, at low pressure. (3) Results: The best values of CO₂ adsorption were obtained with 6% bipyridine: 1.045 mmol·g⁻¹ at 298 K and 2.26 mmol·g⁻¹ at 273 K. (4) Conclusions: The synthetized BTEE/aminopyridine or bipyridine PMO NPs showed significant results and could be promising for carbon capture and storage (CCS) application.     

Iron-siRNA Nanohybrids for Enhanced Chemodynamic Therapy via Ferritin Heavy Chain Downregulation

Ferrous iron (Fe²⁺) has more potent hydroxyl radical (⋅OH)-generating ability than other Fenton-type metal ions, making Fe-based nanomaterials attractive for chemodynamic therapy (CDT). However, because Fe²⁺ can be converted by ferritin heavy chain (FHC) to nontoxic ferric form and then sequestered in ferritin, therapeutic outcomes of Fe-mediated CDT agents are still far from satisfactory. Here we report the synthesis of siRNA-embedded Fe⁰ nanoparticles (Fe⁰-siRNA NPs) for self-reinforcing CDT via FHC downregulation. Upon internalization by cancer cells, pH-responsive Fe⁰-siRNA NPs are degraded to release Fe²⁺ and FHC siRNA in acidic endo/lysosomes with the aid of oxygen (O₂). The accompanied O₂ depletion causes an intracellular pH decrease, which further promotes the degradation of Fe⁰-siRNA NPs. In addition to initiating chemodynamic process, Fe²⁺-catalyzed ⋅OH generation facilitates endo/lysosomal escape of siRNA by disrupting the membranes, enabling FHC downregulation-enhanced CDT.     

Protein nanoparticles containing Cu(II) and DOX for efficient chemodynamic therapy via self-generation of H2O2

Chemodynamic therapy (CDT) refers to generating hydroxyl radical (OH) in tumor sites via hydrogen peroxide (H₂O₂) catalyzed by transition metal ions in cancer cells under acidic environment. However, H₂O₂ content is not enough for effective CDT, although H₂O₂ content in cancer cells is higher than that of normal cells. Herein, we synthesized DOX@BSA-Cu NPs (nanoparticles) for effective CDT by providing enhanced content of H₂O₂ in cancer cells. The results proved Cu²⁺ in NPs could be reduced to Cu⁺ by glutathione (GSH) and effectively converted H₂O₂ to OH. Moreover, the loaded low-dose doxorubicin (DOX) in the NPs could improve the content of H₂O₂ and resulted in more efficient generation of OH in cancer cells. Thus DOX@BSA-Cu NPs exhibited higher cytotoxicity to cancer cells. This research may provide new ideas for the further studies on more effective Cu(II)-based CDT nanoagents.     

Enhancing the photothermal conversion of tetrathiafulvalene-based MOFs by redox doping and plasmon resonance

Near-infrared (NIR) photothermal materials hold great promise for use in several applications, particularly in photothermal therapy, diagnosis, and imaging. However, current NIR responsive materials often show narrow absorption bands and low absorption efficiency, and have long response times. Herein, we demonstrate that the NIR absorption of tetrathiafulvalene-based metal–organic frameworks (MOFs) can be tuned by redox doping and using plasmonic nanoparticles. In this work, a MOF containing redox-active tetrathiafulvalene (TTF) units and Dy-carboxylate chains was constructed, Dy-m-TTFTB. The NIR absorption of the as-synthesized Dy-m-TTFTB was further enhanced by Ag⁺ or I₂ oxidation, transforming the neutral TTF into a TTF˙⁺ radical state. Interestingly, treatment with Ag⁺ not only generated TTF˙⁺ radicals, but it also formed Ag nanoparticles (NPs) in situ within the MOF pores. With both TTF˙⁺ radicals and Ag NPs, Ag NPs@Dy-m-TTFTB was shown to exhibit a wide range of absorption wavelengths (200–1000 nm) and also a high NIR photothermal conversion. When the system was irradiated with an 808 nm laser (energy power of 0.7 W cm⁻²), Ag NPs@Dy-m-TTFTB showed a sharp temperature increase of 239.8 °C. This increase was higher than that of pristine Dy-m-TTFTB (90.1 °C) or I₂ treated I₃⁻@Dy-m-TTFTB (213.0 °C).

The photo-response of the redox-active metal–organic framework has been systematically tuned by incorporating plasmonic Ag nanoparticles and tetrathiafulvalene radicals, resulting in efficient near-infrared photothermal conversion materials.     

Ranolazine-functionalized CuO NPs: efficient homogeneous and heterogeneous catalysts for reduction of 4-nitrophenol

In the present study copper oxide nanoparticles (CuO NPs) were synthesized using a hydrothermal method with ranolazine as a shape-directing agent. Ranolazine-functionalized CuO NPs were characterized by various analytical techniques such as scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The SEM pattern confirmed the morphology of ranolazine-functionalized CuO NPs with well-defined rice-like structures. FTIR spectroscopy confirmed the interaction between CuO NPs and ranolazine. The XRD analysis indicated that the structure of ranolazine-functionalized CuO NPs was monoclinic crystalline and the size ranged between 9 and 18 nm with an average particle size of 12 nm. The smaller size range of CuO NPs gave a large surface area that enhanced the efficiency of these catalysts employed for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the H ₂ O system. In homogeneous catalysis, results showed that 50 μL of CuO NPs was required in the presence of NaBH4 for 99% reduction of 4-NP in 240 s. On the other hand, for heterogeneous catalysis, 0.5 mg of CuO NPs was used in the presence of NaBH4 for 99% catalytic reduction of 4-NP to 4-AP in 320 s. The rate of reaction for homogeneous catalysis and heterogeneous catalysis was determined from the plots of In(Ct /C0) of 4-NP versus time (s), which showed good linearity with values of 1.3 × 10 ^-2 and 8.8 × 10 ^-3 s ^-1 . respectively. The high-quality catalytic efficiency, good reusability, nontoxic nature, and low cost are favorable properties of the synthesized CuO NPs for use as efficient catalysts for reduction of 4-AP to 4-NP in both homogeneous and heterogeneous media.     

One‐Step Synthesis of Small‐Sized and Water‐Soluble NaREF4 Upconversion Nanoparticles for In Vitro Cell Imaging and Drug Delivery

Small (2–28 nm) NaREF₄ (rare earth (RE)=Nd–Lu, Y) nanoparticles (NPs) were prepared by an oil/water two‐phase approach. Meanwhile, hydrophilic NPs can be obtained through a successful phase‐transition process by introducing the amphiphilic surfactant sodium dodecylsulfate (SDS) into the same reaction system. Hollow‐structured NaREF₄ (RE=Y, Yb, Lu) NPs can be fabricated in situ by electron‐beam lithography on solid NPs. The MTT assay indicates that these hydrophilic NPs with hollow structures exhibit good biocompatibility. The as‐prepared hollow‐structured NPs can be used as anti‐cancer drug carriers for drug storage/release investigations. Doxorubicin hydrochloride (DOX) was taken as model drug. The release of DOX from hollow α‐NaLuF₄:20 % Yb³⁺, 2 % Er³⁺ exhibits a pH‐sensitive release patterns. Confocal microscopy observations indicate that the NPs can be taken up by HeLa cells and show obvious anti‐cancer efficacy. Furthermore, α‐NaLuF₄:20 % Yb³⁺, 2 % Er³⁺ NPs show bright‐red emission under IR excitation, making both the excitation and emission light fall within the “optical window” of biological tissues. The application of α‐NaLuF₄:20 % Yb³⁺, 2 % Er³⁺ in the luminescence imaging of cells was also investigated, which shows a bright‐red emission without background noise.     

Correlation of Solubility Thermodynamics of Glibenclamide with Recrystallization and In Vitro Release Profile

The solubility of glibenclamide was evaluated in DMSO, NMP, 1,4-dioxane, PEG 400, Transcutol^® HP, water, and aqueous mixtures (T = 293.15~323.15 K). It was then recrystallized to solvate and compressed into tablets, of which 30-day stability and dissolution was studied. It had a higher solubility in 1,4-dioxane, DMSO, NMP (X_exp = 2.30 × 10³, 3.08 × 10⁴, 2.90 × 10⁴) at 323.15 K, its mixture (X_exp = 1.93 × 10³, 1.89 × 10⁴, 1.58 × 10⁴) at 298.15 K, and 1,4-dioxane (w) + water (1−w) mixture ratio of w = 0.8 (X_exp = 3.74 × 10³) at 323.15 K. Modified Apelblat (RMSD ≤ 0.519) and CNIBS/R-K model (RMSD ≤ 0.358) suggested good comparability with the experimental solubility. The minimum value of ΔG° vs ΔH° at 0.70 < x₂ < 0.80 suggested higher solubility at that molar concentration. Based on the solubility, it was recrystallized into the solvate, which was granulated and compressed into tablets. Among the studied solvates, the tablets of glibenclamide dioxane solvate had a higher initial (95.51%) and 30-day (93.74%) dissolution compared to glibenclamide reference (28.93%). There was no stability issue even after granulation, drying, or at pH 7.4. Thus, glibenclamide dioxane solvate could be an alternative form to improve the molecule’s properties.     

Mesoporous MnSiO3@Fe3O4@C Nanoparticle as pH-responsive T1-T2* Dual-modal Magnetic Resonance Imaging Contrast Agent for Tumor Diagnosis

Mesoporous structured MnSiO₃@Fe₃O₄@C nanoparticles (NPs) were prepared via a facile and efficient strategy, with negligible cytotoxicity and minor side efforts. The asprepared MnSiO₃@Fe₃O₄@C NPs hold great potential in serving as pH-responsive T₁-T₂^* dual-modal magnetic resonance (MR) imaging contrast agents. The released Mn²⁺ shortened T₁ relaxation time, meanwhile the superparamagnetic Fe₃O₄ enhanced T₂ contrast imaging. The release rate of Mn ions reaches 31.66% under the condition of pH=5.0, which is similar to tumor microenvironment and organelles. Cytotoxicity assays show that MnSiO₃@Fe₃O₄@C NPs have minor toxicity, even at high concentrations. After intravenous injection of MnSiO₃@Fe₃O₄@C NPs, a rapid contrast enhancement in tumors was achieved with a significant enhancement of 132% after 24 h of the administration. Moreover, a significant decreasement of 53.8% was witnessed in T₂ MR imaging signal. It demonstrated that MnSiO₃@Fe₃O₄@C NPs can act as both positive and negative MR imaging contrast agents. Besides, owing to the pH-responsive degradation of mesoporous MnSiO₃, MnSiO₃@Fe₃O₄@C NPs can also be used as potential drug systems for cancer theranostics.     

Molecularly Imprinted Silica-Coated CdTe Quantum Dots for Fluorometric Determination of Trace Chloramphenicol

A dual recognition system with a fluorescence quenching of quantum dots (QDs) and specific recognition of molecularly imprinted polymer (MIP) for the detection of chloramphenicol (CAP) was constructed. MIP@SiO₂@QDs was prepared by reverse microemulsion method with 3-aminopropyltriethoxysilane (APTS), tetraethyl orthosilicate (TEOS) and QDs being used as the functional monomer, cross-linker and signal sources, respectively. MIP can specifically recognize CAP, and the fluorescence of QDs can be quenched by CAP due to the photo-induced electron transfer reaction between CAP and QDs. Thus, a method for the trace detection of CAP based on MIP@SiO₂@QDs fluorescence quenching was established. The fluorescence quenching efficiency of MIP@SiO₂@QDs displayed a desirable linear response to the concentration of CAP in the range of 1.00~4.00 × 10² μmol × L⁻¹, and the limit of detection was 0.35 μmol × L⁻¹ (3σ, n = 9). Importantly, MIP@SiO₂@QDs presented good detection selectivity owing to specific recognition for CAP, and was successfully applied to quantify CAP in lake water with the recovery ranging 102.0~104.0%, suggesting this method has the promising potential for the on-site detection of CAP in environmental waters.     

Salt Stress Mitigation via the Foliar Application of Chitosan-Functionalized Selenium and Anatase Titanium Dioxide Nanoparticles in Stevia (Stevia rebaudiana Bertoni)

High salt levels are one of the significant and major limiting factors on crop yield and productivity. Out of the available attempts made against high salt levels, engineered nanoparticles (NPs) have been widely employed and considered as effective strategies in this regard. Of these NPs, titanium dioxide nanoparticles (TiO₂ NPs) and selenium functionalized using chitosan nanoparticles (Cs–Se NPs) were applied for a quite number of plants, but their potential roles for alleviating the adverse effects of salinity on stevia remains unclear. Stevia (Stevia rebaudiana Bertoni) is one of the reputed medicinal plants due to their diterpenoid steviol glycosides (stevioside and rebaudioside A). For this reason, the current study was designed to investigate the potential of TiO₂ NPs (0, 100 and 200 mg L⁻¹) and Cs–Se NPs (0, 10 and 20 mg L⁻¹) to alleviate salt stress (0, 50 and 100 mM NaCl) in stevia. The findings of the study revealed that salinity decreased the growth and photosynthetic traits but resulted in substantial cell damage through increasing H₂O₂ and MDA content, as well as electrolyte leakage (EL). However, the application of TiO₂ NPs (100 mg L⁻¹) and Cs–Se NPs (20 mg L⁻¹) increased the growth, photosynthetic performance and activity of antioxidant enzymes, and decreased the contents of H₂O₂, MDA and EL under the saline conditions. In addition to the enhanced growth and physiological performance of the plant, the essential oil content was also increased with the treatments of TiO₂ (100 mg L⁻¹) and Cs–Se NPs (20 mg L⁻¹). In addition, the tested NPs treatments increased the concentration of stevioside (in the non-saline condition and under salinity stress) and rebaudioside A (under the salinity conditions) in stevia plants. Overall, the current findings suggest that especially 100 mg L⁻¹ TiO₂ NPs and 20 mg L⁻¹ Cs–Se could be considered as promising agents in combating high levels of salinity in the case of stevia.     

Ceria–Zirconia Nanoparticles as an Enhanced Multi‐Antioxidant for Sepsis Treatment

The two oxidation states of ceria nanoparticles, Ce³⁺ and Ce⁴⁺, play a pivotal role in scavenging reactive oxygen species (ROS). In particular, Ce³⁺ is largely responsible for removing O₂⁻ and ^.OH that are associated with inflammatory response and cell death. The synthesis is reported of 2 nm ceria–zirconia nanoparticles (CZ NPs) that possess a higher Ce³⁺/Ce⁴⁺ ratio and faster conversion from Ce⁴⁺ to Ce³⁺ than those exhibited by ceria nanoparticles. The obtained Ce_0.7Zr_0.3O₂ (7CZ) NPs greatly improve ROS scavenging performance, thus regulating inflammatory cells in a very low dose. Moreover, 7CZ NPs are demonstrated to be effective in reducing mortality and systemic inflammation in two representative sepsis models. These findings suggest that 7CZ NPs have the potential as a therapeutic nanomedicine for treating ROS‐related inflammatory diseases.     

Synthesis and Guest-Binding Properties of pH/Reduction Dual-Responsive Cyclophane Dimer

A water-soluble cyclophane dimer having two disulfide groups as a reduction-responsive cleavable bond as well as several acidic and basic functional groups as a pH-responsive ionizable group 1 was successfully synthesized. It was found that 1 showed pH-dependent guest-binding behavior. That is, 1 strongly bound an anionic guest, 6-p-toluidinonaphthalene-2-sulfonate (TNS) with binding constant (K/M⁻¹) for 1:1 host-guest complexes of 9.6 × 10⁴ M⁻¹ at pH 3.8, which was larger than those at pH 7.4 and 10.7 (6.0 × 10⁴ and 2.4 × 10⁴ M⁻¹, respectively), indicating a favorable electrostatic interaction between anionic guest and net cationic 1. What is more, release of the entrapped guest molecules by 1 was easily controlled by pH stimulus. Large favorable enthalpies (ΔH) for formation of host-guest complexes were obtained under the pH conditions employed, suggesting that electrostatic interaction between anionic TNS and 1 was the most important driving force for host-guest complexation. Such contributions of ΔH for formation of host-guest complexes decreased along with increased pH values from acidic to basic solutions. Upon addition of dithiothreitol (DTT) as a reducing reagent to an aqueous PBS buffer (pH 7.4) containing 1 and TNS, the fluorescence intensity originating from the bound guest molecules decreased gradually. A treatment of 1 with DTT gave 2, having less guest-binding affinity by the cleavage of disulfide bonds of 1. Consequently, almost all entrapped guest molecules by 1 were released from the host. Moreover, such reduction-responsive cleavage of 1 and release of bound guest molecules was performed more rapidly in aqueous buffer at pH 10.7.     

Surfactant effects on the particle size,zeta potential,and stability of starch nanoparticles and their use in a pH-responsive manner

Storage conditions seem to be important in the long-term stability of nanoparticles (NPs). This work studies the effects of surfactants and storage container on particle size distribution and zeta potential during long-term storage of acid hydrolyzed potato starch NPs. The NPs were prepared from potato starch using acid hydrolysis and high-intensity ultrasonication. During the ultrasonic treatment, the surfactants were added dropwise to the solutions to reduce the size and stabilize the formed NPs. Particle size distribution, zeta potential, and FE-SEM were used to characterize the ensuing NPs. Additionally, a 5-month stability study was performed to evaluate the maintenance of potato starch NPs over time at different storage conditions. Then, NPs from corn starch were produced by the same procedure and were used for preparing pH-responsive nanocarriers containing NaHCO₃ for delivery of an anti-cancer drug, FTY720. These NPs were able to release the drug at pH 5.0 because of CO₂ generated from NaHCO₃ in acidic pH and released from the NPs by the production of pores, which accelerate drug release.     

Doxorubicin-loaded boron-rich polymer nanoparticles for orthotopically implanted liver tumor treatment

The in vivo behaviors of doxorubicin(DOX)-loaded dextran-poly(3-acrylamidophenylboronic acid)(DextranPAPBA) nanoparticles(NPs) were studied.The DOX-loaded NPs had a narrowly distributed diameter of ca.74 nm and mainly accumulated in liver of tumor-bearing mice after intravenous injection as demonstrated by in vivo real-time near infrared fluorescent imaging.The DOX contents in various tissues were quantified and consisted well with the results of fluorescent imaging.The biodistribution pattern of DOX-loaded NPs encourages us to investigate their liver tumor treatment by using an orthotopically implanted liver tumor model,revealing that the DOX-loaded NPs formulation had better antitumor effect than free DOX.