Interfacial Engineering over Pt-Calcium Ferrite/2D Carbon Nitride Nanosheet p-n Heterojunctions for Superior Photocatalytic Properties.

The present study discloses the fabrication of efficient p-n heterojunctions using n-type polymeric bulk carbon nitride (b-CN, E g = 2.7 eV) or exfoliated nanosheets of carbon nitride (NSCN, E g = 2.9 eV) with p-type spinel ferrite CaFe2O4 (CFO, E g = 1.9 eV) for photocatalytic hydrogen generation. A series of p-n combinations were fabricated and characterized by various techniques. The oxide-carbon nitride interactions, light absorption, band alignment at the interface, and water/H3O+ adsorption capability were elucidated over heterojunctions and correlated with the photocatalytic hydrogen yield. The main developments in the present study are as follows: (1) All heterojunctions were more active than pure phases. (2) The photocatalytic activity trend validated an increase in the lifetime of charge carriers from TRPL. Pt(1 wt %)-CFO(1 wt %)/NSCN (481.5 µmol/h/g under ultraviolet (UV)-visible-simulated light, 147.5 µmol/h/g under CFL illumination for 20 h, τavg = 10.33 ns) > Pt-NSCN > Pt-CFO/b-CN > CFO/NSCN > CFO/b-CN > NSCN > Pt/b-CN > mechanical mixture (MM) of 1 wt %CFO + NSCN-MM > 1 wt %CFO + b-CN-MM > CFO > b-CN (τavg = 4.5 ns). (3) Pt-CFO/NSCN was most active and exhibited 250 times enhanced photocatalytic activity as compared to parent bulk carbon nitride, 6.5 times more active than CFO/NSCN, and twice more active than Pt-NSCN. Thus, enhanced activity is attributed to the smooth channelizing of electrons across p-n junctions. (4) NSCN evidently offered improved characteristics as a support and photocatalyst over b-CN. The exfoliated NSCN occupied a superior few-layer morphology with 0.35 nm width as compared to parent b-CN. NSCN allowed 57% dispersion of 6 nm-sized CFO, while b-CN supported 14% dispersion of 7.8 nm-sized CFO particles, as revealed by small-angle X-ray scattering spectroscopy (SAXS). Sizes of 2-4 nm were observed for Pt nanoparticles in the 1 wt %Pt/1 wt % CFO/NSCN sample. A binding energy shift and an increase in the FWHM of X-ray photoelectron spectroscopy (XPS) core level peaks established charge transfer and enhanced band bending on p-n contact in Pt-CFO/NSCN. FsTAS revealed the decay of photogenerated electrons via trapping in shallow traps (τ1, τ2) and deep traps (τ3). Lifetimes τ1 (3.19 ps, 42%) and τ2 (187 ps, 31%) were higher in NSCN than those in b-CN (τ1 = 2.2 ps, 42%, τ2 = 30 ps, 31%), which verified that the recombination reaction rate was suppressed by 6 times in NSCN (k 2 = 0.53 × 1010 s-1) as compared to b-CN (k 2 = 3.33 × 1010 s-1). Deep traps lie below the H+/H2 reduction potential; thus, electrons in deep traps are not available for photocatalytic H2 generation. (5) The role of CFO in enhancing water adsorption capability was modeled by molecular dynamics. NSCN or b-CN both showed very poor interaction with water molecules; however, the CFO cluster adsorbed H3O+ ions very strongly through the electrostatic interaction between calcium and oxygen (of H3O+). Pt also showed a strong affinity for H2O but not for H3O+. Thus, both CFO and Pt facilitated NSCN to access water molecules, and CFO further sustained the adsorption of H3O+ molecules, crucial for the photocatalytic reduction of water molecules. (6) Band potentials of CFO and NSCN aligned suitably at the interface of CFO/NSCN, resulting in a type-II band structure. Valence band offset (VBO, ΔE VB) and conduction band offset (CBO, ΔE CB) were calculated at the interface, resulting in an effective band gap of 1.41 eV (2.9 - ΔE VB = 1.9 - ΔE CB), much lower than parent compounds. The interfacial band structure was efficient in driving photogenerated electrons from the CB of CFO to the CB of NSCN and holes from the VB of NSCN to the VB of CFO, thus successfully separating charge carriers, as supported by the increased lifetime of charge carriers and favorable photocatalytic H2 yield.

Impact of Ionic Liquids on the Physicochemical Behavior of Vesicles.

The effects of two ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim]BF4) and 1-butyl-1-methyl pyrrolidinium tetrafluoroborate ([bmp]BF4), on a mixture of phospholipids (PLs) 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC), 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), and 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG) (6:3:1, M/M/M, 70% PL) in combination with 30 mol % cholesterol (CHOL) were investigated in the form of a solvent-spread monolayer and bilayer (vesicle). Surface pressure (π)-area (A) isotherm studies, using a Langmuir surface balance, revealed the formation of an expanded monolayer, while the cationic moiety of the IL molecules could electrostatically and hydrophobically bind to the PLs on the palisade layer. Turbidity, dynamic light scattering (size, ζ-potential, and polydispersity index), electron microscopy, small-angle X-ray/neutron scattering, fluorescence spectroscopy, and differential scanning calorimetric studies were carried out to evaluate the effects of IL on the structural organization of bilayer in the vesicles. The ILs could induce vesicle aggregation by acting as a "glue" at lower concentrations (<1.5 mM), while at higher concentrations, the ILs disrupt the bilayer structure. Besides, ILs could result in the thinning of the bilayer, evidenced from the scattering studies. Steady-state fluorescence anisotropy and lifetime studies suggest asymmetric insertion of ILs into the lipid bilayer. MTT assay using human blood lymphocytes indicates the safe application of vesicles in the presence of ILs, with a minimal toxicity of up to 2.5 mM IL in the dispersion. These results are proposed to have applications in the field of drug delivery systems with benign environmental impact.

Synchronized Codelivery of Combination Chemotherapies Intratumorally Using a Lipidic Lyotropic Liquid Crystal System.

In this work, an injectable in situ depot-forming lipidic lyotropic liquid crystal (L3C) system is developed to codeliver a precisely synchronized combination of chemotherapeutics intratumorally. The developed L3C system is composed of amphiphilic lipids and surfactants, including monoolein, phosphatidylcholine, tocopherol acetate, and d-α-tocopherol polyethylene glycol 1000 succinate. Owing to its amphiphilic nature, the developed formulation can coaccommodate both hydrophobic and hydrophilic chemotherapeutic moieties simultaneously. The study presents a proof of concept by designing a combination chemotherapy regimen in vitro and demonstrating its in vivo translation using doxorubicin and paclitaxel as model hydrophilic and hydrophobic drug moieties, respectively. The synchronized combination of the two chemotherapeutics with maximum synergistic activity was identified, coloaded in the developed L3C system at predefined stoichiometric ratios, and evaluated for antitumor efficacy in the 4T1 breast tumor model in BALB/c mice. The drug-loaded L3C formulation is a low-viscosity injectable fluid with a lamellar phase that transforms into a hexagonal mesophase depot system upon intratumoral injection. The drug-loaded depot system locally provides sustained intratumoral delivery of the chemotherapeutics combination at their precisely synchronized ratio for over a period of one month. Results demonstrate that the exposure of the tumor to the precisely synchronized intratumoral chemotherapeutics combination via the developed L3C system resulted in significantly higher antitumor activity and reduced cardiotoxicity compared to the unsynchronized combination chemotherapy or the synchronized but uncoordinated drug delivery administered by a conventional intravenous route. These findings demonstrate the potential of the developed L3C system for achieving synchronized codelivery of the chemotherapeutics combination intratumorally and improving the efficacy of combination chemotherapy.

Smart Magnetic Nanocarriers for Codelivery of Nitric Oxide and Doxorubicin for Enhanced Apoptosis in Cancer Cells.

Extremely short half-life therapeutic molecule nitric oxide (NO) plays significant roles in the functioning of various physiological and pathological processes in the human body, whereas doxorubicin hydrochloride (DOX) is a clinically important anticancer drug widely used in cancer chemotherapy. Thus, the intracellular delivery of these therapeutic molecules is tremendously important to achieve their full potential. Herein, we report a novel approach for the development of highly water-dispersible magnetic nanocarriers for codelivery of NO and DOX. Primarily, bifunctional magnetic nanoparticles enriched with carboxyl and thiol groups were prepared by introducing cysteine onto the surface of citrate-functionalized Fe3O4 nanoparticles. DOX was electrostatically conjugated onto the surface of bifunctional nanoparticles via carboxyl moieties, whereas the thiol group was further nitrosated to provide NO-releasing molecules. The developed magnetic nanocarrier exhibited good aqueous colloidal stability, protein resistance behavior, and high encapsulation efficacy for NO (65.5%) and DOX (85%), as well as sustained release characteristics. Moreover, they showed superior cytotoxicity toward cancer (A549 and MCF-7) cells via apoptosis induction over normal (WI26VA4) cells. Specifically, we have developed magnetic nanocarriers having the capability of dual delivery of NO and DOX, which holds great potential for combinatorial cancer treatment.

Development of a rapid and ultra-sensitive RNA:DNA hybrid immunocapture based biosensor for visual detection of SARS-CoV-2 RNA.

The Development of reliable and field-compatible detection methods is essential to monitoring and controlling the spread of any global pandemic. We herein report a novel anti-RNA:DNA hybrid (anti-RDH) antibody-based biosensor for visual, colorimetric lateral flow assay, using gold nanoparticles, coupled with transcription-mediated-isothermal-RNA-amplification (TMIRA) for specific and sensitive detection of viral RNA. We have demonstrated its utility for SARS-CoV-2 RNA detection. This technique, which we have named RDH-LFA (anti-RNA:DNA hybrid antibody-based lateral flow assay), exploits anti-RDH antibody for immunocapture of viral RNA hybridized with specific DNA probes in lateral flow assay. This method uses biotinylated-oligonucleotides (DNAB) specific to SARS-CoV-2 RNA (vRNA) to generate a vRNA-DNAB hybrid. The biotin-tagged vRNA-DNAB hybrid molecules bind to streptavidin conjugated with gold nanoparticles. This hybrid complex is trapped by the anti-RDH antibody immobilized on the nitrocellulose membrane resulting in pink color signal leading to visual naked-eye detection in 1 minute. Combining RDH-LFA with isothermal RNA amplification (TMIRA) significantly improves the sensitivity (LOD:10 copies/µl) with a total turnaround time of an hour. More importantly, RDH-LFA coupled with the TMIRA method showed 96.6% sensitivity and 100% specificity for clinical samples when compared to a commercial gold standard reverse-transcription quantitative polymerase-chain-reaction assay. Thus, the present study reports a rapid, sensitive, specific, and simple method for visual detection of viral RNA, which can be used at the point-of-care without requiring sophisticated instrumentation.

An Injectable In Situ Depot-Forming Lipidic Lyotropic Liquid Crystal System for Localized Intratumoral Drug Delivery.

To address the need for localized chemotherapy against unresectable solid tumors, an injectable in situ depot-forming lipidic lyotropic liquid crystal system (L3CS) is explored that can provide spatiotemporal control over drug delivery. Although liquid crystals have been studied extensively before but their application as an injectable intratumoral depot system for locoregional chemotherapy has not been explored yet. The developed L3CS in the present study is a low-viscosity injectable fluid having a lamellar phase, which transforms into a hexagonal mesophase depot system on subcutaneous or intratumoral injection. The transformed depot system can be preprogrammed to provide tailored drug release intratumorally, over a period of one week to one month. To establish the efficacy of the developed L3CS, doxorubicin is used as a model drug. The drug release mechanism is studied in detail both in vitro and in vivo, and the efficacy of the developed system is investigated in the murine 4T1 tumor model. The direct intratumoral injection of the L3CS provided localized delivery of doxorubicin inside the tumor and restricted its access within the tumor only for a sustained period of time. This led to an over 10-fold reduction in tumor burden, reduced cardiotoxicity, and a significant increase in the median survival rate, compared to the control group. The developed L3CS thus provides an efficient strategy for localized chemotherapy against unresectable solid tumors with a great degree of spatial and temporal control over drug delivery.

Thermoresponsive liquid crystalline formulation of Exemestane: Design and structural characterization.

Exemestane (EXE), a drug used for the treatment of breast cancer, has limited aqueous solubility of 0.08 mg/mL and log P∼ 4.22. The only available marketed formulation in form of tablets possess limitations of poor oral absorption (∼ 42 %), low solubility, extensive hepatic metabolism and numerous adverse effects due to its peripheral absorption. In order to address these issues, an alternative route of topical application is attempted through a lamellar liquid crystal based formulation. Pluronic® was used as stabilizer due to its higher surface activity and gelling properties. The solubility enhancement of EXE was achieved using liquid crystal formulation. We have investigated the effect of concentration of oil, Smix (surfactant - cosurfactant mixture) and EXE on lattice parameter, rheology and drug release for various combinations of the formulation. The small angle x-ray scattering (SAXS) measurement demonstrated an evidence of a lamellar structure with lattice parameter ∼15 nm, which increases with corresponding increase in oil and EXE due to increase in hydrophobic interactions leading to an expansion of lamella. The inter lamellar distance decreases at higher surfactant concentration, due to the distribution of the same amount of oil and drug within larger concentration of surfactant molecules. The rheology measurement exhibited gel like properties at low shear rate indicating soft gel formation, which converts to Newtonian type flowing liquid at higher shear rate. At constant Smix with increasing oil content, the viscosity decreases, which is attributed to the dilution of the lamellar structures with oil. The temperature sweep rheology reveals a change in the viscosity near physiological temperature, which may be attributed to the structural transition of lamellae. The formulation remains gel like at room temperature, which aids in proper application to skin and converts it to free flowing liquid above 37 °C. The invitro drug release of optimized formulation for 24 h was ∼ 38 % at 37 °C, which increased to 50 % at 42 °C. Accordingly, this formulation containing thermoresponsive lamellar liquid crystal gels of EXE represents a viable option for hyperthermia induced enhanced drug release. The characteristic and advantageous features offered by this formulation includes improved bioavailability of EXE due to enhanced solubility, permeability and absorption.

Bivalirudin and sirolimus co-eluting coronary stent: Potential strategy for the prevention of stent thrombosis and restenosis.

Localized drug delivery with sustained elution characteristics from nanocarrier coated stents represents a viable therapeutic approach to circumvent concerns related to coronary stent therapy. We fabricated a Sirolimus (SRL) and Bivalirudin (BIV) releasing nanoparticles (NPs) coated stent for concurrent mitigation of vascular restenosis and acute stent thrombosis. SRL NPs were prepared by nanoprecipitation method whereas the BIV vesicles were generated using hydrophobic ion pair approach followed by micellization phenomenon. MTT assay and confocal microscopic analysis indicated superior anti-proliferative activity and higher cellular uptake of SRL NPs into human coronary artery smooth muscle cells, respectively. DSC and ATR-FTIR techniques confirmed the formation of complex between BIV and phosphatidylglycerol via some weak physical interactions. More than 2 fold rise in log P value was obtained for DSPG-BIV at 3:1 M ratio compared with native BIV solution. The SAXS analysis indicated formation of oligolamellar vesicles of DSPG-BIV complex which was preferentially entrapped into lipophilic lamellae of vesicles. APTT, PT, and TT tests revealed that the BIV vesicles caused significant prolongation of clotting time compared to native BIV solution. The SEM analysis showed uniform and defect free stent coating. In vitro release study demonstrated that SRL and BIV were eluted in a sustained manner from coated stents.

Spontaneous Formation of Cationic Vesicles in Aqueous DDAB-Lecithin Mixtures for Efficient Plasmid DNA Complexation and Gene Transfection.

Cationic liposomes have become an attractive tool to deliver genes and interfering RNA into cells. Herein, we report the application of spontaneously formed cationic vesicles in mixtures of lecithin and cationic amphiphiles for efficient transfection of plasmid DNA and siRNA into cells. The average hydrodynamic diameter of the phospholipid vesicles was modulated by changing the ratio of dihexadecyldimethylammonium bromide (DDAB) to phospholipid in the vesicles. The vesicles were characterized by dynamic light scattering, ζ potential, and small-angle X-ray scattering. Depending on the ratio of DDAB to phospholipid, the average size of the vesicles can be varied in the range of 150-300 nm with a ζ potential of +40 mV. The ability of these cationic vesicles to form lipoplexes upon binding with pDNA is demonstrated by ζ potential, isothermal titration calorimetry, gel retardation, and DNase I digestion assay. The enthalpy of binding between pDNA and cationic liposome was found to be -5.7 (±0.8) kJ/mol. The cellular uptake studies of lipoplexes observed by fluorescence microscopy confirmed good transfection efficiency of DDAB liposomes in MCF-7 and HeLa cells. The fluorescent imaging analysis showed effective gene delivery and expression of green fluorescent protein. In addition, the formulation has demonstrated an ability to deliver small interfering RNA (siBRD4) for efficient gene silencing as seen by a significant decrease in BRD4 protein level in siBRD4-treated cells. Comparison of the transfection efficiency of different formulations suggests that DDAB-rich mixed phospholipid vesicles with size <200 nm are better than large size vesicles for improved endocytosis and gene expression.

Electrostatically bound lanreotide peptide - gold nanoparticle conjugates for enhanced uptake in SSTR2-positive cancer cells.

Lanreotide peptide (LP) has high affinity to somatostatin receptors like SSTR2 and is commonly used in the treatment of neuro-endocrine tumors. The main objective of this study is to target gold nanoparticles (AuNPs) towards SSTR2-positive cancer cells using lanreotide peptide (LP) as the targeting agent for enhanced tumor uptake and antitumor activity. pH mediated changes in the surface potential of LP and AuNP is used to prepare electrostatically bound AuNP-LP complexes. AuNP-LP complex formation was demonstrated by UV-Visible spectroscopy, surface potential, dynamic light scattering (DLS), small angle X-ray scattering and HR-TEM. Confocal microscopy and flow cytometric studies show that AuNP-LP complex has higher cellular uptake in SSTR2 expressed cancer cells (MCF-7 and AR42J) than in CHO cells. The enhanced cellular uptake of LP coated AuNPs lead to ~1.5 to 2-fold GSH depletion and enhanced ROS generation in MCF-7 cells. The preferential cytotoxicity of the AuNP-LP complex towards MCF-7 and AR42J cells, as revealed by MTT assay, is consistent with the increased cellular uptake. Our studies demonstrate that LP coated AuNP can be used as an effective platform to selectively target SSTR2 positive cancer cells for combination therapy approaches involving gold nanoparticles.