Engineering polymeric microparticles as theranostic carriers for selective delivery and cancer therapy

Formulation, characterization and cellular toxicity assessment of a novel bee-venom microsphere in prostate cancer treatment

Bee venom (B.V.) is a toxin produced naturally by honey bees with several toxic and therapeutic efficacies. It is used in the treatment of different cancer kinds like renal, hepatic, and prostate cancer. Due to its protein nature, it is degraded in the upper gastrointestinal tract. Colon-targeted drug delivery systems represent a useful tool to protect B.V. from degradation and can be administered orally instead of I.V. infusion and traditional bee stinging. In the present study, B.V. loaded enteric-coated cross-linked microspheres were prepared by emulsion cross-linking method. Percentage yield, entrapment efficiency %, swelling degree, and in-vitro release are evaluated for prepared microspheres. Free B.V., optimized microspheres formula (F3), and doxorubicin cytotoxic effects were tested by MTT assay. Results concluded that free B.V. was more effective against the growth of human prostate adenocarcinoma (PC3) cells followed by optimized microspheres than doxorubicin. But both free B.V. and doxorubicin have a cytotoxic effect on normal oral epithelial cells (OEC). According to flow cytometric analysis, the optimized microsphere formula induced apoptosis and reduced necrosis percent at IC₅₀ concentration. Furthermore, microspheres did not affect the viability of OEC. These results revealed that microspheres have a degree of specificity for malignant cells. Therefore, it seems that this targeted formulation could be a good candidate for future clinical trials for cancer therapy.

Silk fibroin hydrogels induced and reinforced by acidic calcium phosphate - A simple way of producing bioactive and drug-loadable composites for biomedical applications

Silk fibroin (SF) hydrogels have attracted extensive interest in biomedical applications due to their biocompatibility and wide availability. However, their generally poor mechanical properties limit their utility. Here, injectable, ready-to-use SF-based composites, simultaneously induced and reinforced by acidic calcium phosphates, were prepared via a dual-paste system requiring no complex chemical/physical treatment. The composite was formed by mixing a monocalcium phosphate monohydrate paste with a β-tricalcium phosphate/SF paste. The conformational transition of SF in an acidic environment forms continuous networks, and the acidic calcium phosphate, brushite and monetite, formed simultaneously in the networks during mixing. The composites displayed a partly elastomeric compression behavior, with mechanical properties increasing with an increasing calcium phosphate and β-sheet content at the lower calcium phosphate contents evaluated (22.2-36.4 wt%). While the stiffness was still relatively low, the materials presented a high elasticity and ductility, and no failure at stresses in the range of failure stresses of trabecular bone. Furthermore, the calcium phosphate confers bioactivity to the material, and the composites with a promising in vitro cell response also showed potential as drug vehicles, using vancomycin as a model drug. These dual-paste systems exhibit potential utility in biomedical applications, such as bone void fillers and drug vehicles.

Temperature Responsive Shape-Memory Scaffolds with Circumferentially Aligned Nanofibers for Guiding Smooth Muscle Cell Behavior

Structural simulation of the smooth muscle layer plays an important role in tissue engineering of blood vessels for the replacement of damaged arteries. However, it is difficult to construct small-diameter tubular scaffolds to homogenously locate and align smooth muscle cells (SMCs). In this work, novel temperature responsive shape-memory scaffolds are designed for SMC culturing. The scaffolds are composed of an outer layer of poly(lactide-glycolide-trimethylene carbonate) (PLGATMC) for programming the deformation from planar to small-diameter tubular shape and an inner layer of aligned nanofibrous membrane of poly(lactide-glycolide)/chitosan (PLGA/CS) to regulate cell adhesion, proliferation, and morphology. The SMC behaviors and functions are dependent on the PLGA/CS ratios of membranes, and the scaffold with PLGA/CS 7:3 membrane exhibits the most suitable ability to regulate SMC behavior. The PLGA/CS@PLGATMC scaffold can be deformed into a temporary planar at 20 °C for convenient seeding and attachment of SMCs and then immediately self-rolled into 3D tube at 37 °C. The proposed strategy offers a practical approach for the development of small-diameter vascular scaffolds from 2D planar into 3D tubular shape by self-rolling.

Comprehensive assessment of Nile tilapia skin collagen sponges as hemostatic dressings

Nile tilapia skin collagen sponge was fabricated by lyophilization and cross-linked with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide in the presence of N-hydroxysuccinimide (EDC/NHS). The physicochemical properties were examined. The EDC/NHS cross-linked collagen sponge presented an enhanced water absorption capacity. In addition, biocompatibility and hemostatic efficiency were evaluated by acute systemic toxicity assay, dermal irritation test, intradermal reaction test, sensitization test, cytotoxicity, blood clotting assay in vitro, and liver and femoral artery hemorrhage models in vivo. Results showed that the produced collagen sponges before and after EDC/NHS cross-linking had excellent biocompatibility. Furthermore, EDC/NHS cross-linking promoted fibroblast cells viability and proliferation reflected by the MTT reduction assay. Meanwhile, EDC/NHS cross-linked collagen sponge exhibited the best blood clotting ability and hemostatic efficiency in rat femoral artery hemorrhage model in comparison with non-crosslinked and commercial collagen sponges. Our results demonstrated that the fabricated collagen sponges could be used as perfect hemostatic dressings.

Cancer Cell Targeting With Functionalized Quantum Dot-Encoded Polyelectrolyte Microcapsules

Imaging agents and drug carriers are commonly targeted toward cancer cell through functionalization with specific recognition molecules. Quantum dots (QDs) are fluorescent semiconductor nanocrystals whose extraordinary brightness and photostability make them attractive for direct fluorescent labeling of biomolecules or optical encoding of the membranes and cells. Here, we analyse the cytotoxicity of QD-encoded microcapsules, validate an approach to the activation of the microcapsule's surface for further functionalization with monoclonal antibody Trastuzumab, a humanized monoclonal antibody targeting the extracellular domain of the human epidermal growth factor receptor 2 (HER2) and already in clinical use for the treatment of HER2 positive breast cancer. In addition, we characterize the cell-specific targeting activity of the resultant bio-conjugate by immunofluorescence assay (IFA) and real-time analysis of interaction of the conjugates with live HER2 overexpressing human breast cancer cells. We demonstrate, that encapsulation of QDs into the polymer shell using the layer-by-layer deposition method yields highly fluorescent polyelectrolyte microcapsules with a homogeneous size distribution and biocompatibility upon in vitro treatment of cancer cells. Carbodiimide surface activation ensures optimal disperse and optical characteristics of the QD-encoded microcapsules before antibody conjugation. The prepared conjugates of the microcapsules with cancer-specific monoclonal antibody targeting HER2 provide sufficiently sensitive and specific antibody-mediated binding of the microcapsules with live cancer cells, which demonstrated their potential as prospective cancer cell–targeting agents.

Bioimaging Tools Based on Polyelectrolyte Microcapsules Encoded with Fluorescent Semiconductor Nanoparticles: Design and Characterization of the Fluorescent Properties

Fluorescent imaging is a widely used technique for detecting and monitoring the distribution, interaction, and transformation processes at molecular, cellular, and tissue level in modern diagnostic and other biomedical applications. Unique photophysical properties of fluorescent semiconductor nanocrystals "quantum dots" (QDs) make them advanced fluorophores for fluorescent labeling of biomolecules or optical encoding of microparticles to be used as bioimaging and theranostic agents in targeted delivery, visualization, diagnostics, and imaging. This paper reports on the results of development of an improved approach to the optical encoding of polyelectrolyte microcapsules with stable, covered with the multifunctional polyethyleneglycol derivatives water-soluble QDs, as well as characterization of the optical properties, morphological and structural properties of the encoded microcapsules. The embedding of QDs into the polymer microcapsule membrane through layer-by-layer deposition on a preliminarily formed polymeric polyelectrolyte shell makes it possible to obtain bright fluorescent particles with an adapted charge and size distribution that are distinctly discernible by flow cytometry as individual homogeneous populations. The fluorescent microcapsules developed can be used in further designing bioimaging and theranostic agents sensitive to various external stimuli along with photoexcitation.

Polymeric Encapsulation of Turmeric Extract for Bioimaging and Antimicrobial Applications

As a herb of the ginger family, the turmeric plant has been used as spice and colorant in the Oriental countries. The rhizome part of the plant is rich in curcumin, which has been proven to be the main ingredient responsible for turmeric's biological effects. Most research endeavors have been upon the investigation of pharmaceutical activities of curcumin, yet the fluorescence of curcumin is a bit far from well-studied. The major drawbacks associated with curcumin are its poor aqueous solubility and low stability. In this communication, the encapsulation of fluorescent turmeric extract into polymeric nanoparticles (NPs) for bioimaging and antibacterial applications is reported. Through poly(d,l-lactic-co-glycolic acid) (PLGA) encapsulation, solubility of curcumin is greatly increased, and the biodegradable nature of PLGA further enhances the biocompatibility of curcumin. These Cur-PLGA NPs are successfully demonstrated to be efficient fluorescence probes for bioimaging, and promising for antibacterial application.

On-demand one-step synthesis of small-sized fluorescent–magnetic bifunctional microparticles on a droplet-splitting chip

Generation of small-sized multifunctional microparticles: multifunctional microparticles were easily produced based on droplet splitting and photopolymerization in a single step.

3D shape evolution of microparticles and 3D enabled applications using non-uniform UV flow lithography (NUFL)

The generation of microparticles with non-spherical morphologies has generated extensive interest because of their enhanced physical properties that can increase their performance in a wide variety of clinical and industrial applications. A flow lithographic technique based on stop flow lithography (SFL) recently showed the ability to fabricate particles with 3D shapes via manipulation of the UV intensity profile in a simple 2D microfluidic channel. Here, we further explore this flow lithographic method, called non-uniform flow lithography (NUFL), to investigate the 3D-shape tuning ability for the generation of 3D magnetic microparticles and their potential applications. We characterize the morphological microparticle shape change through variation of polymerization objective, UV intensity, and solution opacity. We also couple the particles' intrinsic anisotropic magnetic properties with an external magnetic field to create chains of bullet- and bell-shaped particles and a valve-like micromachine. In addition, in contrast to other complex and multi-step methodologies, NUFL shows a simple route for the facile creation of 3D microstructure platforms such as microneedles with fully modifiable tip morphology. This method presents intriguing possibilities for growing research within 3D microstructure assembly, micromachine systems and minimally invasive medical interventions.

Fabrication of luminescent TiO2:Eu3+ and ZrO2:Tb3+ encapsulated PLGA microparticles for bioimaging application with enhanced biocompatibility

Rare earth is of great interest because of their unique optical properties, especially the rich luminescent spectra. In this study, we developed a facile one-pot microwave-assisted synthesis of luminescent Eu³⁺ doped TiO₂ nanoparticles and Tb³⁺ doped ZrO₂ nanoparticles. As a result, the emitting centers (Eu³⁺ and Tb³⁺) were all well dispersed in the amorphous host oxide materials, leading to high luminescence. The obtained TiO₂:Eu³⁺ and ZrO₂:Tb³⁺ nanoparticles were then encapsulated into PLGA microparticles for bio-applications. These luminescent microparticles were then proven to be highly stable, biocompatible and of low cytotoxicity. We successfully demonstrated the bioimaging of live cells using the red-luminescent TiO₂:Eu³⁺ nanoparticles and green-luminescent ZrO₂:Tb³⁺ nanoparticles embedded PLGA microparticles. The microwave-assisted synthetic methodology can be further developed to be general method to prepare oxide nanoparticles.

Synthesis and characterization of magnetite nanoparticles having different cover layer and investigation of cover layer effect on the adsorption of lysozyme and bovine serum albumin

In this study, differently coated superparamagnetic Fe₃O₄ (magnetite) nanoparticles were synthesized, characterized and used for lysozyme (Ly) and bovine serum albumin (BSA) adsorption. SiO₂, carbon nanotubes (CNTs) and graphene were used for covering the readily synthesized magnetite nanoparticles to elucidate the effect of cover layer on the protein adsorption kinetics and capacities of nanostructure. XRD, FTIR, AFM, SEM, VSM and fluorescence measurements were used for the characterization of the samples and investigating the adsorption kinetics of Ly and BSA by these nanoparticles. The average particle size of the Fe₃O₄ nanoparticles are approximately found as 10nm and VSM measurement shows that the Fe₃O₄ particles have superparamagnetic behavior with no hysteresis and remnant. The adsorption kinetic of proteins on nanosized material is followed via fluorescence method. All the nanostructures with different cover layers obey pseudo first order kinetics and SiO₂ coated nanoparticles show the fastest kinetics and capabilities for Ly and BSA adsorption.

Ultrabright organic fluorescent microparticles for in vivo tracing applications

We report the in vivo distribution, toxicity and metabolism of micro-sized fluorescent organic particles and their applications in cerebral blood flow tracing. The fluorescent microparticles exhibit bright fluorescence, good photo-stability and low toxicity; therefore, they are ideal for long-term non-invasive in vivo tracing. In contrast to conventional fluorescent labeling agents, which stain the entire blood vessel, the tracer microparticles can be easily tracked individually and provide vital information about blood flow behavior. Furthermore, we observed stimulated emission from these microparticles in living animals. These microparticles can provide unprecedented contrast for simultaneous observation of the distribution of blood vessels and the dynamics of microcirculation. Pathological examination revealed that the injected microparticles eventually collected in the spleen and liver. We found no observable toxicity of the microparticles to cells or mouse organs. We demonstrate that these fluorescent microparticles are suitable for applications in the field of non-intrusive blood flow tracing and could play a complementary role to traditional imaging agents.

Non-Invasive Imaging Serum Amyloid A Activation through the NF-κB Signal Pathway upon Gold Nanostructure Exposure

With the objective of investigating the acute activation of inflammatory cascades upon exposure to gold nanoparticles (GNPs) as well as detailing the mechanisms, a reporter mouse model that allows for non-invasive and longitudinal imaging of hepatic acute-phase serum amyloid A (SAA) activation is constructed. The model is able to visualize SAA activation at the transcriptional stage, with higher sensitivity than serum protein detection by ELISA. GNPs of various sizes (10-80 nm) and geometries are assessed using the reporter mice with results demonstrating that 50 nm nanospheres (GNS50) possess the highest capacity to induce hepatic SAA activation. Detailed analysis uncovers that resident macrophages in the liver are the main origins of these cytokines and that the exposure to GNS50 significantly induces the M1 macrophage phenotype. Moreover, those M1-polarized macrophages, together with the subsequently secreted pro-inflammatory cytokines, exert effects on hepatocytes and then initiate SAA transcription through the NF-κB signal pathway. The results detail the sequential reactions to GNPs among macrophages, inflammatory mediators, and SAA-synthesizing hepatocytes, which shed light on the acute effects of GNPs on the body. In addition, the established in situ and highly sensitive SAA detection system is expected to have vast applications in evaluating NP-induced acute inflammatory reactions.

Hollow Mesoporous Silica Nanocarriers with Multifunctional Capping Agents for In Vivo Cancer Imaging and Therapy

Efficient drug loading and selectivity in drug delivery are two key features of a good drug-carrier design. Here we report on such a drug carrier formed by using hollow mesoporous silica nanoparticles (HMS NPs) as the core and specifically designed multifunctional amphiphilic agents as the encapsulating shell. These nanocarriers combine the advantages of the HMS NP core (favorable physical and structural properties) and the versatility of an organic-based shell (e.g., specificity in chemical properties and modifiability). Moreover, both the properties of the core and the shell can be independently varied. The varied core and shell could then be integrated into a single device (drug carrier) to provide efficient and specific drug delivery. In vitro and in vivo data suggests that these drug nanocarriers are biocompatible and are able to deliver hydrophobic drugs selectively to target tumor cells. After the break of the pH-labile linkages in the shell, the drug payload can be released and the tumor cells are killed.

Novel Functionalized Selenium Nanoparticles for Enhanced Anti-Hepatocarcinoma Activity In vitro

Selenium nanoparticles loaded with an anticancer molecule offer a new strategy for cancer treatment. In the current study, anisomycin-loaded functionalized selenium nanoparticles (SeNPs@Am) have been made by conjugating anisomycin to the surface of selenium nanoparticles to improve anticancer efficacy. The prepared nanoparticles were fully characterized by transmission electronic microscopy, energy dispersive X-ray spectroscopy, Fourier-transformed infrared spectroscopy, and X-ray photoelectron spectroscopy. The results showed that anisomycin was successfully conjugated with selenium nanoparticles. The size of particles could be effectively regulated through altering the reaction concentrations of sodium selenite and anisomycin. The SeNPs@Am particles (56 nm) exhibited the greatest capacity for cellular uptake. The further study showed that SeNPs@Am entered human hepatocellular carcinoma HepG2 cells in a dose or time-dependent manner via macropinocytosis and clathrin-mediated endocytosis pathways. SeNPs@Am significantly inhibited HepG2 cell proliferation with the low cytotoxicity against normal cells, and dramatically precluded the aggression and migration of HepG2 cells. It also arrested the cell cycle progression at the G0/G1 phase through the activation of the cyclin-dependent kinase inhibitors with inhibition of CDK-2 and ICBP90, and induced the cell apoptosis through activating the caspase cascade signaling in HepG2 cells, markedly superior to anisomycin alone. The findings indicate that SeNPs@Am may be a promising drug for hepatocellular carcinoma.

Conjugated polymer microparticles for selective cancer cell image-guided photothermal therapy

We report conjugated polymers (CPs) microparticles (MPs) for selective cancer cell image-guided photothermal therapy. The CPMPs without surface functionalization can target MCF-7 cancer cells over NIH-3T3 normal cells, while nanoparticles need surface decoration to possess selectivity. Benefitting from large absorption, bright fluorescence, and efficient light-to-heat conversion of CPs, the fabricated MPs can selectively kill MCF-7 cells under NIR infrared laser irradiation.