Quantification of PEG-Maleimide Ligands and Coupling Efficiencies on Nanoparticles with Ellman’s Reagent

Engineering a hierarchically micro-/nanostructured Si@Au-based artificial enzyme with improved accessibility of active sites for enhanced catalysis

The active site accessibility and high loading of gold nanoparticles (AuNPs) are key factors affecting the catalytic activity of supported AuNP-based catalysts. However, the preparation of supported AuNP-based catalysts with highly accessible active sites still remains a challenge. Herein, sphere-on-sphere (SoS) silica microspheres with a hierarchical structure, good dispersion and high surface density of thiol groups (10 SH nm-2) are prepared and used as a platform for the growth of high-density AuNPs. The obtained hierarchical Si@Au micro-/nanostructure consisting of 0.55 μm SoS silica microspheres and 7.3 nm AuNPs (SoS-0.55@Au-7.3) is found to show excellent peroxidase-mimicking activity (Km = 0.033 mM and Vmax = 34.6 × 10-8 M s-1) with merits of high stability and good reusability. Furthermore, the as-obtained SoS-0.55@Au-7.3-based system can sensitively detect hydrogen peroxide (H2O2) with a low detection limit of 1.6 μM and a wide linear range from 2.5 μM to 1.0 mM. The high catalytic activity, excellent stability and good reusability of SoS-0.55@Au-7.3 imply its great prospects in biosensing and biomedical analysis.

Peptide/Nanoparticle Biointerfaces for Multistep Tandem Catalysis

The realization of multifunctional nanoparticle systems is essential to achieve highly efficient catalytic materials for specific applications; however, their production remains quite challenging. They are typically achieved through the incorporation of multiple inorganic components; however, incorporation of functionality could also be achieved at the organic ligand layer. In this work, we demonstrate the generation of multifunctional nanoparticle catalysts using peptide-based ligands for tandem catalytic functionality. To this end, chimeric peptides were designed that incorporated a Au binding sequence and a catalytic sequence that can drive ester hydrolysis. Using this chimera, Au nanoparticles were prepared, which sufficiently presented the catalytic domain of the peptide to drive tandem catalytic processes occurring at the peptide ligand layer and the Au nanoparticle surface. This work represents unique pathways to achieve multifunctionality from nanoparticle systems tuned by both the inorganic and bio/organic components, which could be highly important for applications beyond catalysis, including theranostics, sensing, and energy technologies.

Thiolated chitosan nanoparticles for stable delivery and smart release of As2O3 for liver cancer through dual actions

In this work, multifunctional thiolated chitosan derivatives (DCA-CS-PEG-FA-NAC) were synthesized, and arsenic trioxide (ATO) was loaded onto the derivatives through glutathione (GSH)-sensitive As^III-S bonds, and stable CS-ATO nanodrugs were prepared by simple self-assembly method. By adjusting the thiol substitution degree of CS, the drug loading capacity of the nanodrugs was significantly improved, which could reach 20 ATO per CS molecule (DCA_10.7-CS-PEG_3.1-FA-NAC_20.2-ATO). In vitro release studies obviously showed the low leakage of ATO under physiological conditions while over 95 % ATO was released after 24 h under GSH. In vitro and in vivo investigations demonstrated that the DCA_10.7-CS-PEG_3.1-FA-NAC_20.2-ATO nanodrug could significantly enhance the tumor intracellular accumulation of ATO, reduce the toxic and side effects of ATO on healthy organs, and improve the therapeutic effect of ATO on the HepG2 mice tumor model (tumor inhibition rate was as high as 86.4 %), indicating the potential application of ATO in clinical treatment of liver cancer.

A high-throughput 3D bioprinted cancer cell migration and invasion model with versatile and broad biological applicability

Understanding the underlying mechanisms of migration and metastasis is a key focus of cancer research. There is an urgent need to develop in vitro 3D tumor models that can mimic physiological cell-cell and cell-extracellular matrix interactions, with high reproducibility and that are suitable for high throughput (HTP) drug screening. Here, we developed a HTP 3D bioprinted migration model using a bespoke drop-on-demand bioprinting platform. This HTP platform coupled with tunable hydrogel systems enables (i) the rapid encapsulation of cancer cells within in vivo tumor mimicking matrices, (ii) in situ and real-time measurement of cell movement, (iii) detailed molecular analysis for the study of mechanisms underlying cell migration and invasion, and (iv) the identification of novel therapeutic options. This work demonstrates that this HTP 3D bioprinted cell migration platform has broad applications across quantitative cell and cancer biology as well as drug screening.

Versatile Encapsulation and Synthesis of Potent Liposomes by Thermal Equilibration

The wide-scale use of liposomal delivery systems is challenged by difficulties in obtaining potent liposomal suspensions. Passive and active loading strategies have been proposed to formulate drug encapsulated liposomes but are limited by low efficiencies (passive) or high drug specificities (active). Here, we present an efficient and universal loading strategy for synthesizing therapeutic liposomes. Integrating a thermal equilibration technique with our unique liposome synthesis approach, co-loaded targeting nanovesicles can be engineered in a scalable manner with potencies 200-fold higher than typical passive encapsulation techniques. We demonstrate this capability through simultaneous co-loading of hydrophilic and hydrophobic small molecules and targeted delivery of liposomal Doxorubicin to metastatic breast cancer cell line MDA-MB-231. Molecular dynamic simulations are used to explain interactions between Doxorubicin and liposome membrane during thermal equilibration. By addressing the existing challenges, we have developed an unparalleled approach that will facilitate the formulation of novel theranostic and pharmaceutical strategies.

Modulating defibrillation by tryptophan-mediated photo cleavage of disulfide bonds

Dibenzyloxycarbonyl-l-cystine forms amyloid-like fibers and a hydrogel; however, on UV irradiation, Trp-mediated disulfide bond cleavage occurs, leading to defibrillation and a gel to sol transition.

Cellular defense system-destroying nanoparticles as a platform for enhanced chemotherapy against drug-resistant cancer

Cellular defense system represented by glutathione (GSH) greatly weakens the outcomes of cancer therapy by antioxidation and detoxification. GSH depletion has been proved to be an effective way to enhance the efficacy of reactive oxygen species (ROS)-based therapies and chemotherapy. However, the existing strategies of GSH depletion still face the problems of unclear biosafety and high complexity of multicomponent co-delivery. In this study, we developed a GSH-depleting carrier platform based on disulfide-bridged mesoporous organosilica nanoparticles (MONs) to destroy the cellular defense system for cancer therapy. Responding to the high level of GSH in cancer cells, the disulfide bonds in the framework of MONs could be broken and consumed substantial GSH at the same time. Moreover, this process also promoted the degradation of MONs. In order to evaluate the effect of this platform in cancer therapy, chemotherapeutic drug cisplatin was loaded into MONs (Pt@MONs) to treat drug-resistant non-small cell lung cancer. In vitro and in vivo results indicated that Pt@MONs efficiently triggered GSH depletion, promoted platinum-DNA adduct formation, and induced cell apoptosis, resulting in significant tumor growth inhibition without marked toxicity. Taken together, the cellular defense system-destroying nanoparticles provide a promising platform for enhanced cancer therapy.

Analyzing the surface of functional nanomaterials-how to quantify the total and derivatizable number of functional groups and ligands

Functional nanomaterials (NM) of different size, shape, chemical composition, and surface chemistry are of increasing relevance for many key technologies of the twenty-first century. This includes polymer and silica or silica-coated nanoparticles (NP) with covalently bound surface groups, semiconductor quantum dots (QD), metal and metal oxide NP, and lanthanide-based NP with coordinatively or electrostatically bound ligands, as well as surface-coated nanostructures like micellar encapsulated NP. The surface chemistry can significantly affect the physicochemical properties of NM, their charge, their processability and performance, as well as their impact on human health and the environment. Thus, analytical methods for the characterization of NM surface chemistry regarding chemical identification, quantification, and accessibility of functional groups (FG) and surface ligands bearing such FG are of increasing importance for quality control of NM synthesis up to nanosafety. Here, we provide an overview of analytical methods for FG analysis and quantification with special emphasis on bioanalytically relevant FG broadly utilized for the covalent attachment of biomolecules like proteins, peptides, and oligonucleotides and address method- and material-related challenges and limitations. Analytical techniques reviewed include electrochemical titration methods, optical assays, nuclear magnetic resonance and vibrational spectroscopy, as well as X-ray based and thermal analysis methods, covering the last 5-10 years. Criteria for method classification and evaluation include the need for a signal-generating label, provision of either the total or derivatizable number of FG, need for expensive instrumentation, and suitability for process and production control during NM synthesis and functionalization.

Rationally Designed, Self-Assembling, Multifunctional Hydrogel Depot Repairs Severe Spinal Cord Injury

Following severe spinal cord injury (SCI), dysregulated neuroinflammation causes neuronal and glial apoptosis, resulting in scar and cystic cavity formation during wound healing and ultimately the formation of an atrophic microenvironment that inhibits nerve regrowth. Because of this complex and dynamic pathophysiology, a systemic solution for scar- and cavity-free wound healing with microenvironment remodeling to promote nerve regrowth has rarely been explored. A one-step solution is proposed through a self-assembling, multifunctional hydrogel depot that punctually releases the anti-inflammatory drug methylprednisolone sodium succinate (MPSS) and growth factors (GFs) locally according to pathophysiology to repair severe SCI. Synergistically releasing the anti-inflammatory drug MPSS and GFs in the hydrogel depot throughout SCI pathophysiology protects spared tissues/axons from secondary injury, promotes scar boundary- and cavity-free wound healing, and results in permissive bridges for remarkable axonal regrowth. Behavioral and electrophysiological studies indicate that remnants of spared axons, not regenerating axons, mediate functional recovery, strongly suggesting that additional interventions are still required to render the rebuilt neuronal circuits functional. These findings pave the way for the development of a systemic solution to treat acute SCI.

Development of HER2-Targeting-Ligand-Modified Albumin Nanoparticles Based on the SpyTag/SpyCatcher System for Photothermal Therapy

The successful development of targeted nanoparticle (NP)-based therapeutics depends on the effective conjugation of targeting ligands to the NP. However, conventional methods based on chemical reactive groups such as N-hydroxysuccinimide, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, and maleimide have several limitations, including low binding efficiency, complex reaction methods, long reaction times, and reduced activity of the targeting ligand. In this study, we developed a novel method for conjugating targeting ligands to albumin NPs using the recently developed bacterial superglue the SpyTag/SpyCatcher (ST/SC) ligation system. This method involves a rapid one-step conjugation process with almost 100% efficiency. Albumin NPs conjugated to human epidermal growth factor receptor 2 (HER2) affibody molecules using the ST/SC system showed strong binding to HER2-overexpressing cells. In addition, NPs encapsulated with indocyanine green accumulated in cells overexpressing HER2 and exhibited superior photothermal treatment effects. Thus, surface functionalization of NPs using the ST/SC reaction may be used to develop new nanosystems that exhibit improved therapeutic benefits.

Conjugation of biphenyl groups with poly(ethylene glycol) to enhance inhibitory effects on the PD-1/PD-L1 immune checkpoint interaction

Monoclonal antibodies have been developed as anticancer agents to block immune checkpoint pathways associated with programmed cell death 1 (PD-1) and its ligand PD-L1. However, the high cost of antibodies has encouraged researchers to develop other inhibitor types. Here, biphenyl compounds were conjugated with poly(ethylene glycol) (PEG) to enhance the activity of small molecular inhibitors. Immunoassay results revealed the decrease in the inhibition activity following conjugation with linear PEG, suggesting that the PEG moiety reduced the interaction between the biphenyl structure and PD-L1. However, the inhibitory effect on PD-1/PD-L1 interaction was further enhanced by using branched PEG conjugates. The increase in the number of conjugated biphenyl compounds resulted in increased inhibitory activity. The highest IC50 value was 0.33 μM, which was about 5 times higher than that observed for a non-conjugated monovalent compound. The inhibitory activity was more than 20 times the activity reported for the starting compound. Considering the increase in the inhibition activity, this multivalent strategy can be useful in the design of new immune checkpoint inhibitors.

Bone-Targeting Prodrug Mesoporous Silica-Based Nanoreactor with Reactive Oxygen Species Burst for Enhanced Chemotherapy

Cancer remains a primary threat to human lives. Recently, amplification of tumor-associated reactive oxygen species (ROS) has been used as a boosting strategy to improve tumor therapy. Here, we report on a bone-targeting prodrug mesoporous silica-based nanoreactor for combined photodynamic therapy (PDT) and enhanced chemotherapy for osteosarcoma. Because of surface modification of a bone-targeting biphosphate moiety and the enhanced permeability and retention effect, the formed nanoreactor shows efficient accumulation in osteosarcoma and exhibits long-term retention in the tumor microenvironment. Upon laser irradiation, the loaded photosensitizer chlorin e6 (Ce6) produces in situ ROS, which not only works for PDT but also functions as a trigger for controlled release of doxorubicin (DOX) and doxycycline (DOXY) from the prodrugs based on a thioketal (TK) linkage. The released DOXY further promotes ROS production, thus perpetuating subsequent DOX/DOXY release and ROS burst. The ROS amplification induces long-term high oxidative stress, which increases the sensitivity of the osteosarcoma to chemotherapy, therefore resulting in enhanced tumor cell inhibition and apoptosis. The as-developed nanoreactor with combined PDT and enhanced chemotherapy based on ROS amplification shows significant promise as a potential platform for cancer treatment.

Trastuzumab Targeted Neratinib Loaded Poly-Amidoamine Dendrimer Nanocapsules for Breast Cancer Therapy

Background

Human epidermal growth factor receptor2 (Her2) positive breast cancer represents 25% of breast cancer cases. Targeted therapy with Her2 monoclonal antibody, trastuzumab (TZ), represents the first-line treatment for this type of breast cancer. In addition, neratinib, an irreversible inhibitor of the HER-2 receptor tyrosine kinase, has recently been approved as adjuvant therapy to TZ. This study aims to formulate (TZ)-grafted dendrimers loaded with neratinib, allowing a dual treatment alongside reducing the associated resistance as well as targeted therapy.

Methods

TZ was conjugated on the surface of dendrimer using hetero-cross linker, MAL-PEG-NHS, and the zeta potential, and in vitro release of neratinib from dendrimers was characterized. Formulated dendrimers were also fluorescently conjugated with fluorescein isothiocyanate to visualize and quantify their SKBR-3 cellular uptake.

Results

The G4 PAMAM dendrimer showed successful encapsulation of neratinib and a sustained release profile. Comparative in vitro studies revealed that these TZ-targeted dendrimers loaded with neratinib were more selective and have higher antiproliferation activity against SKBR-3 cells compared to neratinib alone and neratinib loaded dendrimer.

Conclusion

In the current study, neratinib loaded in plain and trastuzumab-grafted dendrimer were successfully prepared. Enhanced cellular uptake of trastuzumab conjugated dendrimers was shown, together with a higher cytotoxic effect than plain neratinib dendrimers. These findings suggest the potential of TZ-conjugated dendrimers as targeting carrier for cytotoxic drugs, including neratinib.

Determining Whether Agonist Density or Agonist Number Is More Important for Immune Activation via Micoparticle Based Assay

It is unknown if surface bound toll-like-receptor (TLR) agonists activate cells via density or total molecular number. To answer this question, we developed a TLR agonist surface conjugated polystyrene microparticle (MP) system. Using a library of MPs with varying TLR agonist density and number, we simultaneously observed innate immune cell MP uptake and TNFα expression using ImageStream flow cytometry on a cell by cell basis. The data shows that total TLR number and not density drives cellular activation with a threshold of approximately 105-106 TLR agonists. We believe that this information will be crucial for the design of particulate vaccine formulations.

Facile incorporation of DNA-templated quantum dots for sensitive electrochemical detection of the oral cancer biomarker interleukin-8

Recent studies reveal a great value of interleukin-8 (IL-8), a pro-inflammatory cytokine, as a potent biomarker for early diagnosis of oral cancer. Herein, a new electrochemical method is proposed to detect IL-8 by facilely incorporating DNA-templated quantum dots (QDs). In principle, target IL-8 is first treated with the reducing agent tris(2-carboxyethyl)phosphine (TCEP) to yield active thiols and then captured by antibody-functionalized magnetic beads (MBs). Thereafter, via the Michael addition reaction between the active thiol and maleimide group, a maleimide-modified DNA probe is linked to the surface of MBs, which can initiate a process of rolling circle amplification. In this way, long-range DNA strands are generated on the MB surface, subsequently recruiting DNA-templated CdTe/CdS QDs (DNA-QDs) to act as electrochemical reporters. By tracing the responses of DNA-QDs, the method allows IL-8 detection in a linear range from 5 to 5000 fg/mL with a detection limit of 3.36 fg/mL. The selectivity, reproducibility, and applicability in complex serum samples are also demonstrated to be favorable, indicating that the method may have a great potential in the future. More importantly, the use of TCEP treatment in the method not only provides a facile way to incorporate DNA-QDs, avoiding the complicated and time-consuming preparation process of antibody-DNA conjugates or functional nanomaterials; but also makes the method capable of being extended to detect other protein biomarkers in view of widespread presence of disulfides, which may hold a broad potential to facilitate efficient biosensing designs.

Nanomedicines - Tiny particles and big challenges

After decades of research, nanotechnology has been used in a broad array of biomedical products including medical devices, drug products, drug substances, and pharmaceutical-grade excipients. But like many great achievements in science, there is a fine balance between the risks and opportunities of this new technology. Some materials and surface structures in the nanosize range can exert unexpected toxicities and merit a more detailed safety assessment. Regulatory agencies such as the United States Food and Drug Administration or the European Medicines Agency have started dealing with the potential risks posed by nanomaterials. Considering that a thorough characterization is one of the key aspects of controlling such risks this review presents the regulatory background of nanosafety assessment and provides some practical advice on how to characterize nanomaterials and drug formulations. Further, the challenges of how to maintain and monitor pharmaceutical quality through a highly complex production processes will be discussed.

Surface Modifications for Photon-Upconversion-Based Energy-Transfer Nanoprobes

An emerging class of inorganic optical reporters are near-infrared (NIR) excitable lanthanide-based upconversion nanoparticles (UCNPs) with multicolor emission and long luminescence lifetimes in the range of several hundred microseconds. For the design of chemical sensors and optical probes that reveal analyte-specific changes in their spectroscopic properties, these nanomaterials must be combined with sensitive indicator dyes that change their absorption and/or fluorescence properties selectively upon interaction with their target analyte, utilizing either resonance energy transfer (RET) processes or reabsorption-related inner filter effects. The rational development of UCNP-based nanoprobes for chemical sensing and imaging in a biological environment requires reliable methods for the surface functionalization of UCNPs, the analysis and quantification of surface groups, a high colloidal stability of UCNPs in aqueous media as well as the chemically stable attachment of the indicator molecules, and suitable instrumentation for the spectroscopic characterization of the energy-transfer systems and the derived nanosensors. These topics are highlighted in the following feature article, and examples of functionalized core-shell nanoprobes for the sensing of different biologically relevant analytes in aqueous environments will be presented. Special emphasis is placed on the intracellular sensing of pH.

Quantification of amine functional groups on silica nanoparticles: a multi-method approach

Surface chemistry is an important factor for quality control during production of nanomaterials and for controlling their behavior in applications and when released into the environment. Here we report a comparison of four methods for quantifying amine functional groups on silica nanoparticles (NPs). Two colorimetric assays are examined, ninhydrin and 4-nitrobenzaldehyde, which are convenient for routine analysis and report on reagent accessible amines. Results from the study of a range of commercial NPs with different sizes and surface loadings show that the assays account for 50-100% of the total amine content, as determined by dissolution of NPs under basic conditions and quantification by solution-state ¹H NMR. To validate the surface quantification by the colorimetric assays, the NPs are modified with a trifluoromethylated benzaldehyde probe to enhance sensitivity for quantitative ¹⁹F solid state NMR and X-ray photoelectron spectroscopy (XPS). Good agreement between the assays and the determination from solid-state NMR is reinforced by elemental ratios from XPS, which indicate that in most cases the difference between total and accessible amine content reflects amines that are outside the depth probed by XPS. Overall the combined results serve to validate the relatively simple colorimetric assays and indicate that the reactions are efficient at quantifying surface amines, by contrast to some other covalent modifications that have been employed for functional group quantification.

Lipid-nucleic acid nanoparticles of novel ionizable lipids for systemic BMP-9 gene delivery to bone-marrow mesenchymal stem cells for osteoinduction

Rational design of novel ionizable lipids for development of lipid-nucleic acid nanoparticles (LNP) is required for safe and effective systemic gene delivery for osteoporosis. LNPs require suitable characteristics for intravenous administration and effective accumulation in bone marrow for enhanced transfection. Hence, lipids with C18 tail and ionizable headgroup (Boc-His-ODA/BHODA and His-ODA/HODA) were synthesized and characterized physicochemically. LNPs were prepared with bone morphogenetic protein-9 gene (BHODA-LNP, HODA-LNP, and bone-homing peptide targeted HODA-LNP - HODA-LNPT). Thorough physicochemical (electrolyte stability, DNase I and serum stability) and biological (hemolysis, ROS induction, cytotoxicity and transfection) characterization was carried out followed by acute toxicity studies and therapeutic performance studies in ovariectomized rat model. Lipids with pH dependent ionization were successfully synthesized. LNPs thereof were ∼100 nm size with stability against electrolytes, DNase I and serum and exhibited low hemolytic potential demonstrating suitability for intravenous administration. LNPs exhibited minimal cytotoxicity, non-significant ROS induction and high transfection. In vivo studies demonstrated safety and improved bone regeneration in OVX rats with HODA-LNPT showing significantly better performance. Synthesized ionizable lipids offer safe and effective alternative for preparation of LNPs for gene delivery. Targeted BMP-9 LNP show potential for systemic osteoporosis treatment.

Sterically Stabilized RIPL Peptide-Conjugated Nanostructured Lipid Carriers: Characterization, Cellular Uptake, Cytotoxicity, and Biodistribution

As a platform for hepsin-specific drug delivery, we previously prepared IPLVVPLRRRRRRRRC peptide (RIPL)-conjugated nanostructured lipid carriers (RIPL-NLCs) composed of Labrafil® M 1944 CS (liquid oil) and Precirol® ATO 5 (solid lipid). In this study, to prevent the recognition by the mononuclear phagocyte system, polyethylene glycol (PEG)-modified RIPL-NLCs (PEG-RIPL-NLCs) were prepared using PEG3000 at different grafting ratios (1, 5, and 10 mole %). All prepared NLCs showed a homogeneous dispersion (130⁻280 nm), with zeta potentials varying from -18 to 10 mV. Docetaxel (DTX) was successfully encapsulated in NLCs: encapsulation efficiency (93⁻95%); drug-loading capacity (102⁻109 µg/mg). PEG-RIPL-NLCs with a grafting ratio of 5% PEG or higher showed significantly reduced protein adsorption and macrophage phagocytosis. The uptake of PEG(5%)-RIPL-NLCs by cancer cell lines was somewhat lower than that of RIPL-NLCs because of the PEG-induced steric hindrance; however, the uptake level of PEG-RIPL-NLCs was still greater than that of plain NLCs. In vivo biodistribution was evaluated after tail vein injection of NLCs to normal mice. Compared to RIPL-NLCs, PEG(5%)-RIPL-NLCs showed lower accumulation in the liver, spleen, and lung. In conclusion, we found that PEG(5%)-RIPL-NLCs could be a promising nanocarrier for selective drug targeting with a high payload of poorly water-soluble drugs.

RIPL peptide-conjugated nanostructured lipid carriers for enhanced intracellular drug delivery to hepsin-expressing cancer cells

Background

To facilitate selective and enhanced drug delivery to hepsin (Hpn)-expressing cancer cells, RIPL peptide (IPLVVPLRRRRRRRRC, 16-mer)-conjugated nanostructured lipid carriers (RIPL-NLCs) were developed.

Methods

NLCs were prepared using a solvent emulsification-evaporation method and the RIPL peptide was conjugated to the maleimide-derivatized NLCs via the thiol-maleimide reaction. Employing a fluorescent probe (DiI), in vitro target-selective intracellular uptake behaviors were observed using fluorescence microscopy and flow cytometry. Separately, docetaxel (DTX) was encapsulated by pre-loading technique, then cytotoxicity and drug release were evaluated. In vivo antitumor efficacy was investigated in BALB/c nude mice with SKOV3 cell tumors after intratumoral injections of different DTX formulations at a dose equivalent to 10 mg/kg DTX.

Results

RIPL-NLCs showed positively charged nanodispersion, whereas NLCs were negatively charged. DTX was successfully encapsulated with an encapsulation efficiency and drug loading capacity of 95-98% and 44-46 µg/mg, respectively. DTX release was diffusion-controlled, revealing the best fit to the Higuchi equation. Cellular uptake of DiI-loaded RIPL-NLCs was 8.3- and 6.2-fold higher than that of DiI-loaded NLCs, in Hpn(+) SKOV3 and LNCaP cells, respectively. The translocation of RIPL-NLCs into SKOV3 cells was time-dependent with internalization within 1 h and distribution throughout the cytoplasm after 2 h. DTX-loaded RIPL-NLCs (DTX-RIPL-NLCs) revealed dose-dependent in vitro cytotoxicity, while drug-free formulations were non-cytotoxic. In SKOV3-bearing xenograft mouse model, DTX-RIPL-NLCs significantly inhibited tumor growth: the inhibition ratios of the DTX solution-treated and DTX-RIPL-NLC-treated groups were 61.4% and 91.2%, respectively, compared to those of the saline-treated group (control).

Conclusion

RIPL-NLCs are good candidates for Hpn-selective drug targeting with a high loading capacity of hydrophobic drug molecules.

PEGylation for enhancing nanoparticle diffusion in mucus

The viscoelastic mucus secretions coating exposed organs such as the lung airways and the female reproductive tract can trap and quickly eliminate not only foreign pathogens and ultrafine particles but also particle-based drug delivery systems, thus limiting sustained and targeted drug delivery at mucosal surfaces. To improve particle distribution across the mucosa and enhance delivery to the underlying epithelium, many investigators have sought to develop nanoparticles capable of readily traversing mucus. The first synthetic nanoparticles shown capable of rapidly penetrating physiological mucus secretions utilized a dense coating of polyethylene glycol (PEG) covalently grafted onto the surface of preformed polymeric nanoparticles. In the decade since, PEG has become the gold standard in engineering mucus-penetrating drug carriers for sustained and targeted drug delivery to the lungs, gastrointestinal tract, eyes, and female reproductive tract. This review summarizes the history of the development of various PEG-based mucus-penetrating particles, and highlights the key physicochemical properties of PEG coatings and PEGylation strategies to achieve muco-inert PEG coatings on nanoparticle drug carriers for improved drug and gene delivery at mucosal surfaces.

Black Phosphorus and its Biomedical Applications

Black phosphorus (BP), also known as phosphorene, has attracted recent scientific attention since its first successful exfoliation in 2014 owing to its unique structure and properties. In particular, its exceptional attributes, such as the excellent optical and mechanical properties, electrical conductivity and electron-transfer capacity, contribute to its increasing demand as an alternative to graphene-based materials in biomedical applications. Although the outlook of this material seems promising, its practical applications are still highly challenging. In this review article, we discuss the unique properties of BP, which make it a potential platform for biomedical applications compared to other 2D materials, including graphene, molybdenum disulphide (MoS2), tungsten diselenide (WSe2) and hexagonal boron nitride (h-BN). We then introduce various synthesis methods of BP and review its latest progress in biomedical applications, such as biosensing, drug delivery, photoacoustic imaging and cancer therapies (i.e., photothermal and photodynamic therapies). Lastly, the existing challenges and future perspective of BP in biomedical applications are briefly discussed.

Data on atherosclerosis specific antibody conjugation to nanoemulsions

This article present data related to the publication entitled “Iron oxide core oil-in-water nanoemulsion as tracer for atherosclerosis MPI and MRI imaging” (Prévot et al., 2017) [1]. Herein we describe the engineering in the baculovirus-insect cell system and purification processes of the human scFv-Fc TEG4-2C antibody, specific of platelets within the atheroma plaque. For molecular targeting purpose, atheroma specific antibody was conjugated to nanoemulsions (NEs) using a heterobifunctional linker (DSPE-PEG-maleimide). Atheroma labelling was assayed by immunochemistry on arterial sections from rabbits.

Ultrasmall AGuIX theranostic nanoparticles for vascular-targeted interstitial photodynamic therapy of glioblastoma

Despite combined treatments, glioblastoma outcome remains poor with frequent local recurrences, indicating that a more efficient and local therapy is needed. In this way, vascular-targeted photodynamic therapy (VTP) could help tumor eradication by destroying its neovessels. In this study, we designed a polysiloxane-based nanoparticle (NP) combining a magnetic resonance imaging (MRI) contrast agent, a photosensitizer (PS) and a new ligand peptide motif (KDKPPR) targeting neuropilin-1 (NRP-1), a receptor overexpressed by angiogenic endothelial cells of the tumor vasculature. This structure achieves the detection of the tumor tissue and its proliferating part by MRI analysis, followed by its treatment by VTP. The photophysical properties of the PS and the peptide affinity for NRP-1 recombinant protein were preserved after the functionalization of NPs. Cellular uptake of NPs by human umbilical vein endothelial cells (HUVEC) was increased twice compared to NPs without the KDKPPR peptide moiety or conjugated with a scramble peptide. NPs induced no cytotoxicity without light exposure but conferred a photocytotoxic effect to cells after photodynamic therapy (PDT). The in vivo selectivity, evaluated using a skinfold chamber model in mice, confirms that the functionalized NPs with KDKPPR peptide moiety were localized in the tumor vessel wall.

Ellman's and Aldrithiol Assay as Versatile and Complementary Tools for the Quantification of Thiol Groups and Ligands on Nanomaterials

Simple, fast, and versatile methods for the quantification of thiol groups are of considerable interest not only for protein analysis but also for the characterization of the surface chemistry of nanomaterials stabilized with thiol ligands or bearing thiol groups for the subsequent (bio-) functionalization via maleimide-thiol chemistry. Here, we compare two simple colorimetric assays, the widely used Ellman's assay performed at alkaline pH and the aldrithiol assay executed at acidic and neutral pH, with respect to their potential for the quantification of thiol groups and thiol ligands on different types of nanoparticles like polystyrene nanoparticles, semiconductor nanocrystals (SC NC), and noble metal particles, and we derive criteria for their use. In order to assess the underlying reaction mechanisms and to obtain stoichiometry factors mandatory for reliable thiol quantification, both methods were studied photometrically and with electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS), thereby demonstrating the influence of different thiols on the reaction mechanism. Our results underline the suitability of both methods for the quantification of directly accessible thiol groups or ligands on the surface of 2D- and 3D-supports, here exemplarily polystyrene nanoparticles. Moreover, we could derive strategies for the use of these simple assays for the determination of masked (i.e., not directly accessible) thiol groups like disulfides such as lipoic acid and thiol stabilizing ligands coordinatively bound to Cd and/or Hg surface atoms of II/VI and ternary SC NC and to gold and silver nanoparticles.

Streptavidin conjugation and quantification-a method evaluation for nanoparticles

Aiming at the development of validated protocols for protein conjugation of nanomaterials and the determination of protein labeling densities, we systematically assessed the conjugation of the model protein streptavidin (SAv) to 100-, 500-, and 1000-nm-sized polystyrene and silica nanoparticles and dye-encoded polymer particles with two established conjugation chemistries, based upon achievable coupling efficiencies and labeling densities. Bioconjugation reactions compared included EDC/sulfo NHS ester chemistry for direct binding of the SAv to carboxyl groups at the particle surface and maleimide-thiol chemistry in conjunction with heterobifunctional PEG linkers and aminated nanoparticles (NPs). Quantification of the total and functional amounts of SAv on these nanomaterials and unreacted SAv in solution was performed with the BCA assay and the biotin-FITC (BF) titration, relying on different signal generation principles, which are thus prone to different interferences. Our results revealed a clear influence of the conjugation chemistry on the amount of NP crosslinking, yet under optimized reaction conditions, EDC/sulfo NHS ester chemistry and the attachment via heterobifunctional PEG linkers led to comparably efficient SAv coupling and good labeling densities. Particle size can obviously affect protein labeling densities and particularly protein functionality, especially for larger particles. For unstained nanoparticles, direct bioconjugation seems to be the most efficient strategy, whereas for dye-encoded nanoparticles, PEG linkers are to be favored for the prevention of dye-protein interactions which can affect protein functionality specifically in the case of direct SAv binding. Moreover, an influence of particle size on achievable protein labeling densities and protein functionality could be demonstrated.

pH and concentration dependence of the optical properties of thiol-capped CdTe nanocrystals in water and D2O

The optical properties of semiconductor nanocrystals (SC NCs) are largely controlled by their size and surface chemistry, i.e., the chemical nature and number of surface ligands as well as the strength of the particle-ligand bond.