Stealth PEGylated polycyanoacrylate nanoparticles for intravenous administration and splenic targeting

Spleen-targeted delivery systems and strategies for spleen-related diseases

The spleen, body's largest secondary lymphoid organ, is also a vital hematopoietic and immunological organ. It is regarded as one of the most significant organs in humans. As more researchers recognize the functions of the spleen, clinical methods for treating splenic diseases and spleen-targeted drug delivery systems to improve the efficacy of spleen-related therapies have gradually developed. Many modification strategies (size, charge, ligand, protein corona) and hitchhiking strategies (erythrocytes, neutrophils) of nanoparticles (NPs) have shown a significant increase in spleen targeting efficiency. However, most of the targeted drug therapy strategies for the spleen are to enhance or inhibit the immune function of the spleen to achieve therapeutic effects, and there are few studies on spleen-related diseases. In this review, we not only provide a detailed summary of the design rules for spleen-targeted drug delivery systems in recent years, but also introduce common spleen diseases (splenic tumors, splenic injuries, and splenomegaly) with the hopes of generating more ideas for future spleen research.

Formulating 10-hydroxycamptothecin into nanoemulsion with functional excipient tributyrin: An innovative strategy for targeted hepatic cancer chemotherapy

This study aimed to develop an innovative dosage form for 10-hydroxycamptothecin (HCPT), a chemotherapeutic agent with limited aqueous solubility and stability, to enhance its parenteral delivery and targeting to hepatic cancer. We formulated HCPT into a nanoemulsion using tributyrin, a dietary component with histone deacetylase inhibitor activity. The resulting HCPT-loaded tributyrin nanoemulsion (Tri-HCPT-E) underwent extensive evaluations. Tri-HCPT-E significantly improved the aqueous solubility, stability, and anti-cancer activities in HepG2 cells. Pharmacokinetic studies confirmed the increased stability and hepatic targeting, with Tri-HCPT-E leading to a 120-fold increase in plasma exposure of intact HCPT and a 10-fold increase in hepatic exposure compared to the commercial free solution. Co-administration of 17α-ethynylestradiol, an up-regulator of low-density lipoprotein (LDL) receptor, further enhanced the distribution and metabolism of HCPT, demonstrating an association between the LDL receptor pathway and hepatic targeting. Most importantly, Tri-HCPT-E exhibited superior in vivo anti-cancer efficacy in a mouse xenograft model compared to the commercial formulation, without causing escalated hepatic or renal toxicity. In conclusion, formulating HCPT into a nanoemulsion with tributyrin has proven to be an innovative and effective strategy for targeted hepatic cancer chemotherapy while tributyrin, a pharmacologically active dietary component, has emerged as a promising functional excipient for drug delivery.

mRNA vaccine designs for optimal adjuvanticity and delivery

Adjuvanticity and delivery are crucial facets of mRNA vaccine design. In modern mRNA vaccines, adjuvant functions are integrated into mRNA vaccine nanoparticles, allowing the co-delivery of antigen mRNA and adjuvants in a unified, all-in-one formulation. In this formulation, many mRNA vaccines utilize the immunostimulating properties of mRNA and vaccine carrier components, including lipids and polymers, as adjuvants. However, careful design is necessary, as excessive adjuvanticity and activation of improper innate immune signalling can conversely hinder vaccination efficacy and trigger adverse effects. mRNA vaccines also require delivery systems to achieve antigen expression in antigen-presenting cells (APCs) within lymphoid organs. Some vaccines directly target APCs in the lymphoid organs, while others rely on APCs migration to the draining lymph nodes after taking up mRNA vaccines. This review explores the current mechanistic understanding of these processes and the ongoing efforts to improve vaccine safety and efficacy based on this understanding.

Extending the In Vivo Residence Time of Macrophage Membrane-Coated Nanoparticles through Genetic Modification

Nanoparticles coated with natural cell membranes have emerged as a promising class of biomimetic nanomedicine with significant clinical potential. Among them, macrophage membrane-coated nanoparticles hold particular appeal due to their versatility in drug delivery and biological neutralization applications. This study employs a genetic engineering approach to enhance their in vivo residence times, aiming to further improve their performance. Specifically, macrophages are engineered to express proline-alanine-serine (PAS) peptide chains, which provide additional protection against opsonization and phagocytosis. The resulting modified nanoparticles demonstrate prolonged residence times when administered intravenously or introduced intratracheally, surpassing those coated with the wild-type membrane. The longer residence times also contribute to enhanced nanoparticle efficacy in inhibiting inflammatory cytokines in mouse models of lipopolysaccharide-induced lung injury and sublethal endotoxemia, respectively. This study underscores the effectiveness of genetic modification in extending the in vivo residence times of macrophage membrane-coated nanoparticles. This approach can be readily extended to modify other cell membrane-coated nanoparticles toward more favorable biomedical applications.

Cancer treatment and toxicity outlook of nanoparticles

Diversified nanosystems with tunable physicochemical attributes have emerged as potential solution to globally devastating cancer by offering novel possibilities for improving the techniques of cancer detection, imaging, therapies, diagnosis, drug delivery and treatment. Drug delivery systems based on nanoparticles (NPs) with ability of crossing different biological barriers are becoming increasingly popular. Besides, NPs are utilized in pharmaceutical sciences to mitigate the toxicity of conventional cancer therapeutics. However, significant NPs-associated toxicity, off-targeted activities, and low biocompatibility limit their utilization for cancer theranostics and can be hazardous to cancer patients up to life-threatening conditions. NPs interact with the biomolecules and disturb their regular function by aggregating inside cells and forming a protein corona, and the formulation turns ineffective in controlling cancer cell growth. The adverse interactions between NPs and biological entities can lead to life-threatening toxicities. This review focuses on the widespread use of various NPs including zinc oxide, titanium oxide, silver, and gold, which serve as efficient nano-vehicles and demonstrate notable pharmacokinetic and pharmacodynamic advantages in cancer therapy. Subsequently, the mechanism of nanotoxicity attached with these NPs, alternate solutions and their prospect to revolutionize cancer theranostics are highlighted. This review will serve as guide for future developments associated with high-performance NPs with controlled toxicity for establishing them as modern-age nanotools to manage cancer in tailored manner.

Recent Advances of Emerging Spleen-Targeting Nanovaccines for Immunotherapy

Vaccines provide a powerful tool to modulate the immune system for human disease prevention and treatment. Classical vaccines mainly initiate immune responses in the lymph nodes (LNs) after subcutaneous injection. However, some vaccines suffer from inefficient delivery of antigens to LNs, undesired inflammation, and slow immune induction when encountering the rapid proliferation of tumors. Alternatively, the spleen, as the largest secondary lymphoid organ with a high density of antigen-presenting cells (APCs) and lymphocytes, acts as an emerging target organ for vaccinations in the body. Upon intravenous administration, the rationally designed spleen-targeting nanovaccines can be internalized by the APCs in the spleen to induce selective antigen presentation to T and B cells in their specific sub-regions, thereby rapidly boosting durable cellular and humoral immunity. Herein, the recent advances of spleen-targeting nanovaccines for immunotherapy based on the anatomical architectures and functional zones of the spleen, as well as their limitations and perspectives for clinical applications are systematically summarized. The aim is to emphasize the design of innovative nanovaccines for enhanced immunotherapy of intractable diseases in the future.

Modulation of release and pharmacokinetics from nanoscale lipid prodrugs of dexamethasone with variable linkage chemistry

In an attempt to tune drug release and subsequent pharmacokinetics once administered intravenously, we have synthesized three lipid-drug conjugates (LDCs) of dexamethasone (DXM) each possessing a different lipid-drug chemical linkage: namely ester, carbamate and carbonate. These LDCs were thoroughly characterized before being turned into nanoscale particles by an emulsion-evaporation process using DSPE-PEG2000 (Distearoyl-sn-Glycero-3-Phosphoethanolamine-N-(methoxy(polyethylene glycol)-2000) as the only excipient. Spherical nanoparticles (NPs) of about 140-170 nm, with a negative zeta potential, were obtained for each LDC and exhibited good stability upon storage at 4 °C for 45 days with no recrystallization of LDCs observed. LDC encapsulation efficacy was above 95% for the three LDCs, leading to a LDC loading of about 90% and an equivalent DXM loading above 50%. Although the ester and carbonate NPs did not exhibit any toxicity up to an equivalent DXM concentration of 100 μg/mL, the carbamate LDC NPs appeared very toxic towards RAW 264.7 macrophages and were discarded. Both ester and carbonate LDC NPs were shown to exert anti-inflammatory activity on LPS-activated macrophages. DXM release from LDC NPs in murine plasma was faster from ester than from carbonate NPs. Finally, pharmacokinetics and biodistribution were conducted, showing a lower exposure to DXM from carbonate LDC NPs than from ester LDC NPs, correlated with the slower DXM release from carbonate LDC NPs. These results outline the need for extended studies to find the best prodrug system for extended drug release.

Pharmacokinetics and tumor delivery of nanoparticles

Nanoparticles (NPs) have been widely used in different areas, including consumer products and medicine. In terms of biomedical applications, NPs or NP-based drug formulations have been extensively investigated for cancer diagnostics and therapy in preclinical studies, but the clinical translation rate is low. Therefore, a thorough and comprehensive understanding of the pharmacokinetics of NPs, especially in drug delivery efficiency to the target therapeutic tissue tumor, is important to design more effective nanomedicines and for proper assessment of the safety and risk of NPs. This review article focuses on the pharmacokinetics of both organic and inorganic NPs and their tumor delivery efficiencies, as well as the associated mechanisms involved. We discuss the absorption, distribution, metabolism, and excretion (ADME) processes following different routes of exposure and the mechanisms involved. Many physicochemical properties and experimental factors, including particle type, size, surface charge, zeta potential, surface coating, protein binding, dose, exposure route, species, cancer type, and tumor size can affect NP pharmacokinetics and tumor delivery efficiency. NPs can be absorbed with varying degrees following different exposure routes and mainly accumulate in liver and spleen, but also distribute to other tissues such as heart, lung, kidney and tumor tissues; and subsequently get metabolized and/or excreted mainly through hepatobiliary and renal elimination. Passive and active targeting strategies are the two major mechanisms of tumor delivery, while active targeting tends to have less toxicity and higher delivery efficiency through direct interaction between ligands and receptors. We also discuss challenges and perspectives remaining in the field of pharmacokinetics and tumor delivery efficiency of NPs.

Physicochemical properties, pharmacokinetics, toxicology and application of nanocarriers

As a promising delivery nanosystem for drug controlled-release, nanocarriers (NCs) have been investigated widely. Although various studies have concentrated on the preparation and characterization of nanoparticles (NPs), clinical applications are rarely reported, due to the unclear distribution, absorption, metabolism, toxicology processes and drug release mechanism. The clinical application of NCs is therefore still a long way off. This review describes the effects of the properties of NCs (including size, shape, surface properties, porosity, elasticity and so on) on pharmacological and toxicological behaviours in vivo and medical applications. Moreover, this study is intended to help the readers understand the behaviours and mechanisms of NCs and positively face the challenges caused by the variety of complicated and limited processes of NCs in vivo. Importantly, this article provides some strategies for the clinical application of NCs and may provide ideas to enhance the therapeutic efficacy of NCs without increasing the toxicology, by introducing tracing technology, which can be more suitable in contributing to the development of safety and efficacy of NCs and the growth of nanotechnology.

Dual imaging modality of fluorescence and transmission X-rays for gold nanoparticle-injected living mice

BACKGROUND

X-ray fluorescence (XRF) imaging for metal nanoparticles (MNPs) is a promising molecular imaging modality that can determine dynamic biodistributions of MNPs. However, it has the limitation that it only provides functional information.

PURPOSE

In this study, we aim to show the feasibility of acquiring functional and anatomic information on the same platform by demonstrating a dual imaging modality of pinhole XRF and computed tomography (CT) for gold nanoparticle (GNP)-injected living mice.

METHODS

By installing a transmission CT detector in an existing pinhole XRF imaging system using a two-dimensional (2D) cadmium zinc telluride (CZT) gamma camera, XRF and CT images were acquired on the same platform. Due to the optimal X-ray spectra for XRF and CT image acquisition being different, XRF and CT imaging were performed by 140 and 50 kV X-rays, respectively. An amount of 40 mg GNPs (1.9 nm in diameter) suspended in 0.20 ml of phosphate-buffered saline were injected into the three BALB/c mice via a tail vein. Then, the kidney and tumor slices of mice were scanned at specific time points within 60 min to acquire time-lapse in vivo biodistributions of GNPs. XRF images were directly acquired without image reconstruction using a pinhole collimator and a 2D CZT gamma camera. Subsequently, CT images were acquired by performing CT scans. In order to confirm the validity of the functional information provided by the XRF image, the CT image was fused with the XRF image. After the XRF and CT scan, the mice were euthanized, and major organs (kidneys, tumor, liver, and spleen) were extracted. The ex vivo GNP concentrations of the extracted organs were measured by inductively coupled plasma mass spectrometry (ICP-MS) and L-shell XRF detection system using a silicon drift detector, then compared with the in vivo GNP concentrations measured by the pinhole XRF imaging system.

RESULTS

Time-lapse XRF images were directly acquired without rotation and translation of imaging objects within an acquisition time of 2 min per slice. Due to the short image acquisition time, the time-lapse in vivo biodistribution of GNPs was acquired in the organs of the mice. CT images were fused with the XRF images and successfully confirmed the validity of the XRF images. The difference in ex vivo GNP concentrations measured by the L-shell XRF detection system and ICP-MS was 0.0005-0.02% by the weight of gold (wt%). Notably, the in vivo and ex vivo GNP concentrations in the kidneys of three mice were comparable with a difference of 0.01-0.08 wt%.

CONCLUSIONS

A dual imaging modality of pinhole XRF and CT imaging system and L-shell XRF detection system were successfully developed. The developed systems are a promising modality for in vivo imaging and ex vivo quantification for preclinical studies using MNPs. In addition, we discussed further improvements for the routine preclinical applications of the systems.

Insights on Development Aspects of Polymeric Nanocarriers: The Translation from Bench to Clinic

Scientists are focusing immense attention on polymeric nanocarriers as a prominent delivery vehicle for several biomedical applications including diagnosis of diseases, delivery of therapeutic agents, peptides, proteins, genes, siRNA, and vaccines due to their exciting physicochemical characteristics which circumvent degradation of unstable drugs, reduce toxic side effects through controlled release, and improve bioavailability. Polymers-based nanocarriers offer numerous benefits for in vivo drug delivery such as biocompatibility, biodegradability, non-immunogenicity, active drug targeting via surface modification, and controlled release due to their pH—and thermosensitive characteristics. Despite their potential for medicinal use, regulatory approval has been achieved for just a few. In this review, we discuss the historical development of polymers starting from their initial design to their evolution as nanocarriers for therapeutic delivery of drugs, peptides, and genes. The review article also expresses the applications of polymeric nanocarriers in the pharmaceutical and medical industry with a special emphasis on oral, ocular, parenteral, and topical application of drugs, peptides, and genes over the last two decades. The review further examines the practical, regulatory, and clinical considerations of the polymeric nanocarriers, their safety issues, and directinos for future research.

A robust approach to make inorganic nanovectors biotraceable

Nuclear medicine imaging plays an important role in nanomedicine. However, it is still challenging to develop a versatile platform to make the nonviral nanovectors used in cancer therapy biotraceable. In the present study, a robust approach to radiolabel inorganic nanovectors for SPECT and PET imaging was developed. The approach was based on the bisphosphonates (BP) conjugated on the nanovector, mesoporous silicon (PSi) nanoparticles. BP served as an efficient chelator for various radionuclides. For both of the ^99mTc and ⁶⁸Ga radionuclides utilized, the radiochemical purity and radiochemical yield were ∼99% and ∼90%, respectively. Because of the short decay time of the radionuclides, an easy, fast and effective PEGylation method was developed to improve the residence time in systemic circulation. Both PEG-^99mTc-BP-PSi and PEG-⁶⁸Ga-BP-PSi NPs, where PEGylation was performed after the labeling, had excellent colloidal and radiochemical stability in vitro. The plain particles without PEGylation accumulated fast in the reticuloendothelial system organs upon intravenous administration, while PEGylation prolonged the residence time of the particles in systemic circulation. Overall, the developed approach proved to be applicable for labeling nonviral nanovectors with various radionuclides easily and robustly. Considering the nature of mesoporous nanoparticles, the approach does not hamper the addition of other functionalities on the vector, nor its capability to carry high payloads.

Towards principled design of cancer nanomedicine to accelerate clinical translation

Nanotechnology in medical applications, especially in oncology as drug delivery systems, has recently shown promising results. However, although these advances have been promising in the pre-clinical stages, the clinical translation of this technology is challenging. To create drug delivery systems with increased treatment efficacy for clinical translation, the physicochemical characteristics of nanoparticles such as size, shape, elasticity (flexibility/rigidity), surface chemistry, and surface charge can be specified to optimize efficiency for a given application. Consequently, interdisciplinary researchers have focused on producing biocompatible materials, production technologies, or new formulations for efficient loading, and high stability. The effects of design parameters can be studied in vitro, in vivo, or using computational models, with the goal of understanding how they affect nanoparticle biophysics and their interactions with cells. The present review summarizes the advances and technologies in the production and design of cancer nanomedicines to achieve clinical translation and commercialization. We also highlight existing challenges and opportunities in the field.

Functionalized Nanoparticles Targeting Tumor-Associated Macrophages as Cancer Therapy

The tumor microenvironment (TME) plays a central role in regulating antitumor immune responses. As an important part of the TME, alternatively activated type 2 (M2) macrophages drive the development of primary and secondary tumors by promoting tumor cell proliferation, tumor angiogenesis, extracellular matrix remodeling and overall immunosuppression. Immunotherapy approaches targeting tumor-associated macrophages (TAMs) in order to reduce the immunosuppressive state in the TME have received great attention. Although these methods hold great potential for the treatment of several cancers, they also face some limitations, such as the fast degradation rate of drugs and drug-induced cytotoxicity of organs and tissues. Nanomedicine formulations that prevent TAM signaling and recruitment to the TME or deplete M2 TAMs to reduce tumor growth and metastasis represent encouraging novel strategies in cancer therapy. They allow the specific delivery of antitumor drugs to the tumor area, thereby reducing side effects associated with systemic application. In this review, we give an overview of TAM biology and the current state of nanomedicines that target M2 macrophages in the course of cancer immunotherapy, with a specific focus on nanoparticles (NPs). We summarize how different types of NPs target M2 TAMs, and how the physicochemical properties of NPs (size, shape, charge and targeting ligands) influence NP uptake by TAMs in vitro and in vivo in the TME. Furthermore, we provide a comparative analysis of passive and active NP-based TAM-targeting strategies and discuss their therapeutic potential.

Nanogels: A novel approach in antimicrobial delivery systems and antimicrobial coatings

The implementation of nanotechnology to develop efficient antimicrobial systems has a significant impact on the prospects of the biomedical field. Nanogels are soft polymeric particles with an internally cross-linked structure, which behave as hydrogels and can be reversibly hydrated/dehydrated (swollen/shrunken) by the dispersing solvent and external stimuli. Their excellent properties, such as biocompatibility, colloidal stability, high water content, desirable mechanical properties, tunable chemical functionalities, and interior gel-like network for the incorporation of biomolecules, make them fascinating in the field of biological/biomedical applications. In this review, various approaches will be discussed and compared to the newly developed nanogel technology in terms of efficiency and applicability for determining their potential role in combating infections in the biomedical area including implant-associated infections.

Renal Cell-Targeted Drug Delivery Strategy for Acute Kidney Injury and Chronic Kidney Disease: A Mini-Review

Kidney diseases, including acute kidney injury (AKI) and chronic kidney disease (CKD), have become a global public health concern associated with high morbidity, mortality, and healthcare costs. However, at present, very few effective and specific drug therapies are available, owing to the poor therapeutic efficacy and systemic side effects. Kidney-targeted drug delivery, as a potential strategy for solving these problems, has received great attention in the fields of AKI and CKD in recent years. Here, we review the literature on renal targeted, more specifically, renal cell-targeted formulations of AKI and CKD that offered biodistribution data. First, we provide a broad overview of the unique structural characteristics and injured cells of acute and chronic injured kidneys. We then separately summarize literature examples of renal targeted formulations according to the difference of target cells and elaborate on the appropriate formulation design criteria for AKI and CKD. Finally, we propose a hypothetic strategy to improve the renal accumulation of glomerular cell-targeted formulation by escaping the uptake of the reticuloendothelial system and provide some perspectives for future studies.

The protein corona and its effects on nanoparticle-based drug delivery systems

In most cases, once nanoparticles (NPs) enter the blood, their surface is covered by biological molecules, especially proteins, forming a so-called protein corona (PC). As a result, what the cells of the body "see" is not the NPs as formulated by the chemists, but the PC. In this way, the PC can influence the effects of the NPs and even mask the desired effects of the NP components. While this can argue for trying to inhibit protein-nanomaterial interactions, encapsulating NPs in an endogenous PC may increase their clinical usefulness. In this review, we briefly introduce the concept of the PC, its formation and its effects on the behavior of NPs. We also discuss how to reduce the formation of PCs or exploit them to enhance NP functions. Studying the interactions between proteins and NPs will provide insights into their clinical activity in health and disease. STATEMENT OF SIGNIFICANCE: The formation of protein corona (PC) will affect the operation of nanoparticles (NPs) in vivo. Since there are many proteins in the blood, it is impossible to completely overcome the formation of PC. Therefore, the use of PCs to deliver drug is the best choice. De-opsonins adsorbed on NPs can reduce macrophage phagocytosis and cytotoxicity of NPs, and prolong their circulation in blood. Albumin, apolipoprotein and transferrin are typical de-opsonins. In present review, we mainly discuss how to optimize the delivery of nanoparticles through the formation of albumin corona, transferrin corona and apolipoprotein corona in vivo or in vitro.

Development of Polymeric Nanoparticles for Blood-Brain Barrier Transfer-Strategies and Challenges

Neurological disorders such as Alzheimer's disease, stroke, and brain cancers are difficult to treat with current drugs as their delivery efficacy to the brain is severely hampered by the presence of the blood-brain barrier (BBB). Drug delivery systems have been extensively explored in recent decades aiming to circumvent this barrier. In particular, polymeric nanoparticles have shown enormous potentials owing to their unique properties, such as high tunability, ease of synthesis, and control over drug release profile. However, careful analysis of their performance in effective drug transport across the BBB should be performed using clinically relevant testing models. In this review, polymeric nanoparticle systems for drug delivery to the central nervous system are discussed with an emphasis on the effects of particle size, shape, and surface modifications on BBB penetration. Moreover, the authors critically analyze the current in vitro and in vivo models used to evaluate BBB penetration efficacy, including the latest developments in the BBB-on-a-chip models. Finally, the challenges and future perspectives for the development of polymeric nanoparticles to combat neurological disorders are discussed.

The biological fate of the polymer nanocarrier material monomethoxy poly(ethylene glycol)-block-poly(d,l-lactic acid) in rat

Monomethoxy poly(ethylene glycol)-block-poly(d,l-lactic acid) (PEG-PLA) is a typical amphiphilic di-block copolymer widely used as a nanoparticle carrier (nanocarrier) in drug delivery. Understanding the in vivo fate of PEG-PLA is required to evaluate its overall safety and promote the development of PEG-PLA-based nanocarrier drug delivery systems. However, acquiring such understanding is limited by the lack of a suitable analytical method for the bioassay of PEG-PLA. In this study, the pharmacokinetics, biodistribution, metabolism and excretion of PEG-PLA were investigated in rat after intravenous administration. The results show that unchanged PEG-PLA is mainly distributed to spleen, liver, and kidney before being eliminated in urine over 48 h mainly (>80%) in the form of its PEG metabolite. Our study provides a clear and comprehensive picture of the in vivo fate of PEG-PLA which we anticipate will facilitate the scientific design and safety evaluation of PEG-PLA-based nanocarrier drug delivery systems and thereby enhance their clinical development.

Evaluation of Low Molecular Weight Cross Linked Chitosan Nanoparticles, to Enhance the Bioavailability of 5-Flourouracil

The present study aimed to formulate 5-fluorouracil loaded cross linked chitosan nanoparticles based on chemical cross-linking of low molecular weight chitosan with glutaraldehyde by reverse micelles technique as 5-FU is less hydrophobic, relatively potent, has a shorter half-life, is rapidly metabolized, less tolerated, and has low oral bioavailability; therefore, we aimed to formulate potential nanocarriers of 5-FU for efficient drug delivery to specific targeted areas of action, reduce oral toxicity, improve tolerability and therapeutic outcomes of 5-FU, in a restricted fashion to enhance the bioavailability of 5-FU. Nanoparticles were formulated by the reverse micelle method based on the chemical cross-linking of glutaraldehyde (25% aqueous solution) into a w/o emulsion in different ratios. LMWCH-NPs were characterized for post-formulation parameters by mean particle size, zeta potential, %age yield, loading/entrapment efficiency, Fourier transform infrared spectroscopy (FTIR), DSC/TGA, TEM, PXRD, drug release at pH 1.2, and pH 7.4. 5-FU loaded NPs showed a size range (198 nm-200 nm) and zeta potential (-39mV to -41mV), which ensured mechanical stability and increased retention time in blood vessels by the sustained release properties of biodegradable nanocarrier drug delivery systems. % age yield showed the range 92% to 96% while % LC ranged 2.0% to 3.4% and %EE ranged 40% to 43%. The TEM images showed spherical nanoparticles. FTIR revealed the compatibility between the drug and the cross-linked polymer. DSC/TGA ensured the thermal stability of the drug, while the solid-state stability of the drug-loaded cross-linked chitosan nanoparticles was evaluated by powder X-ray diffraction (PXRD) analysis. Drug release studies were performed using the dialysis bag technique at both pH (1.2 and 7.4) to mimic the gastrointestinal tract. Highly stable NPs displayed targeted release in phosphate buffer pH 7.4 at 37°C. Fickian diffusion was the predominant release with an R2 value of 0.9975-0.9973-and an N value 0.45-0.53. Prepared nanoparticles are inert, biodegradable, and biocompatible drug delivery systems for sustained release of 5-FU with maximum therapeutic efficacy and bioavailability.

Black Phosphorus Nanosheets Induced Oxidative Stress In Vitro and Targeted Photo-thermal Antitumor Therapy

Black phosphorus (BP) nanosheets with excellent features have been broadly employed for cancer therapy. BPs in blood were known to form BP nanomaterial-corona complexes, yet not explored their biological effects. In this study, BPs as delivery vehicles loaded with doxorubicin (DOX) (BP-DOX) by electrostatic interaction had been successfully prepared for photo-thermal/chemotherapy with a tumor inhibition rate of 81.47% more than the rates of BPs (69.50%) and free DOX (51.91%) in the Hela-bearing mice model by a pH/photo-responsive controlled drug release property. Then, in vivo experiments demonstrated that the treatment of healthy mice with BPs led to mild inflammation in the body and oxidative stress in the liver and lung which caused cell apoptosis. In vitro studies further showed that oxidative stress and metabolic disorders could be induced by BPs in A549, HepG2, Beas-2B, and LO2 cells. Lastly, the RGD peptide-conjugated red blood cell (RBC) membrane-coated BPs (RGD-RBC@BP) was prepared by lipid insertion and co-ultrasound methods for efficient photo-thermal therapy (PTT) cancer via a tumor-targeted strategy. RGD-RBC@BP showed positive biocompatibility, photo-thermal properties, and increased cellular uptake by Hela cells benefited by the long circulation property of RBC and RGD peptides. Pharmacokinetics and bio-distribution study of RGD-RBC@BP were found to prolong circulation time and tended to accumulate in the tumors, which overexpression of ανβ3 integrin rather than livers after intravenous injection 24 h in vivo. After 808 nm laser irradiation, RGD-RBC@BP nanoparticles exhibited a better PTT than PEGylated BPs (BP-PEG). The active-targeting strategy of biomimetic nanomaterials based on the tumor microenvironment have been proved to have favorable biological prospects in cancer PTT.

Hybrid magneto-luminescent iron oxide nanocubes functionalized with europium complexes: synthesis, hemolytic properties and protein corona formation

The use of hybrid nanostructures based on magneto-luminescent properties is a promising strategy for nano-bio applications and theranostics platforms. In this work, we carried out the synthesis and functionalization of iron oxide nanocubes (IONCs) to obtain multifunctional hybrid nanostructures towards biomedical applications. The IONCs were functionalized with tetraethylorthosilicate, thenoyltrifluoroacetone-propyl-triethoxysilane and europium(iii)-dibenzoylmethane complexes to obtain the materials termed as IOCNCs@SiO₂, IONCs@SiO₂TTA, IONCs@SiO₂TTA-Eu and IONCs@SiO₂-TTA-Eu-DBM, respectively. Then, the biological interactions of these nanostructures with red blood cells - RBCs (hemolysis) and human blood plasma (protein corona formation) were evaluated. The XPS spectrocopy and EDS chemical mapping analysis showed that each domain is homogeneously occupied in the hybrid material, with the magnetic core at the center and the luminescent domain on the surface of the hybrid nanomaterial with a core@shell like structure. Futhermore, after each functionalization step, the nanomaterial surface charge drastically changed, with critical impact on RBC lysis and corona formation. While IONCs@SiO₂ and IONCs@SiO₂-TTA-Eu-DBM showed hemolytic properties in a dose-dependent manner, the IONCs@SiO₂TTA-Eu did not present any hemolytic effect up to 300 μg mL^-1. Protein corona results showed a pattern of selective adsorption of proteins with each surface of the synthesized hybrid materials. However, as a general result, a suppression of hemolysis after protein corona formation in all tests was verified. Finally, this study provides a solid background for further applications of these hybrid magneto-luminescent materials containing new surface functionalities in the emerging field of medical nanobiotechnology.

From adsorption to covalent bonding: Apolipoprotein E functionalization of polymeric nanoparticles for drug delivery across the blood-brain barrier

The blood-brain barrier (BBB) is composed of brain endothelial cells, pericytes, and astrocytes, which build a tight cellular barrier. Therapeutic (macro)molecules are not able to transit through the BBB in their free form. This limitation is bypassed by apolipoprotein E (ApoE)-functionalized polymeric nanoparticles (NPs) that are able to transport drugs (e.g. dalargin, loperamide, doxorubicin, nerve growth factor) across the BBB via low density lipoprotein (LDL) receptor mediated transcytosis. Coating with polysorbate 80 or poloxamer 188 facilitates ApoE adsorption onto polymeric NPs enabling recognition by LDL receptors of brain endothelial cells. This effect is even enhanced when NPs are directly coated with ApoE without surfactant anchor. Similarly, covalent coupling of ApoE to NPs that bear reactive groups on their surface leads to significantly improved brain uptake while avoiding the use of surfactants. Several in vitro BBB models using brain endothelial cells or co-cultures with astrocytes/pericytes/glioma cells are described which provide first insights regarding the ability of a drug delivery system to cross this barrier. In vivo models are employed to simulate central nervous system-relevant diseases such as Alzheimer's or Parkinson's disease and cerebral cancer.

Stimulus-cleavable chemistry in the field of controlled drug delivery

This review comprehensively summarises stimulus-cleavable linkers from various research areas and their cleavage mechanisms, thus provides an insightful guideline to extend their potential applications to controlled drug release from nanomaterials.

Brain Delivery of Nanomedicines: Trojan Horse Liposomes for Plasmid DNA Gene Therapy of the Brain

Non-viral gene therapy of the brain is enabled by the development of plasmid DNA brain delivery technology, which requires the engineering and manufacturing of nanomedicines that cross the blood-brain barrier (BBB). The development of such nanomedicines is a multi-faceted problem that requires progress at multiple levels. First, the type of nanocontainer, e.g., nanoparticle or liposome, which encapsulates the plasmid DNA, must be developed. Second, the type of molecular Trojan horse, e.g., peptide or receptor-specific monoclonal antibody (MAb), must be selected for incorporation on the surface of the nanomedicine, as this Trojan horse engages specific receptors expressed on the BBB, and the brain cell membrane, to trigger transport of the nanomedicine from blood into brain cells beyond the BBB. Third, the plasmid DNA must be engineered without bacterial elements, such as antibiotic resistance genes, to enable administration to humans; the plasmid DNA must also be engineered with tissue-specific gene promoters upstream of the therapeutic gene, to insure gene expression in the target organ with minimal off-target expression. Fourth, upstream manufacturing of the nanomedicine must be developed and scalable so as to meet market demand for the target disease, e.g., annual long-term treatment of 1,000 patients with an orphan disease, short term treatment of 10,000 patients with malignant glioma, or 100,000 patients with new onset Parkinson's disease. Fifth, downstream manufacturing problems, such as nanomedicine lyophilization, must be solved to ensure the nanomedicine has a commercially viable shelf-life for treatment of CNS disease in humans.

The Contribution of PEG Molecular Weights in PEGylated Emulsions to the Various Phases in the Accelerated Blood Clearance (ABC) Phenomenon in Rats

PEGylated preparations will be cleared rapidly from blood circulation when they are administrated twice in the same animal at a time interval, referred to as the "accelerated blood clearance" (ABC) phenomenon. Commonly, the study of the ABC phenomenon was investigated in two aspects: induction phase and effectuation phase. Herein, we report the influence of physicochemical properties (PEG molecular weights) in the induction phase and effectuation phase on the ABC phenomenon. In the experiment, on one hand, PEGylated emulsions with different molecular weights of PEG (refer to PEn, n = 400, 600, 800, 1000, 2000, and 5000) were injected for the first dose (induction phase) and induced PE2000 to produce ABC phenomenon. On the other hand, after PE2000 injected, PEn was injected for the second dose (effectuation phase). The results indicated that PE2000 and PE5000 induced an intense ABC phenomenon by their long-circulating characteristic. Interestingly, PE400, PE600, PE800, and PE1000 produced a consistent ABC phenomenon but different circulation time. Apparently, the induction of the ABC phenomenon is not only determined by the circulation time but also by the PEG molecular weights. When PEn is in the effectuation phase, the extent of the ABC phenomenon was not positively related to the molecular weights of PEG, increasing first and then weaken with the increase of molecular weights of PEG. These suggest that the number of -(CH₂CH₂O)_n- repeat units of PE2000 was more conducive to interact with anti-PEG IgM. The results reported here clearly indicate that both the PEG molecular weights of prior dose and the subsequent dose of emulsion strongly influence the extent of the ABC phenomenon. Taken together, our observations in this study complete the effect of PEG molecular weights at a different phase of the ABC phenomenon. Furthermore, our findings have a significant impact on the choice of molecular weights for PEGylated formulations for use in cross-administration.

Multifunctional Microparticles Incorporating Gold Compound Inhibit Human Lung Cancer Xenograft

PURPOSE

Gold porphyrin (AuP) is a complex that has been shown to be potent against various tumors. A biocompatible interpenetrating network (IPN) system comprised of polyethyleneglycol diacrylate (PEGdA) and chemically-modified gelatin has been shown to be an effective implantable drug depot to deliver AuP locally. Here we designed IPN microparticles complexed with AuP to facilitate intravenous administration and to diminish systemic toxicity.

METHODS

We have synthesized and optimized an IPN microparticle formulation complexed with AuP. Tumor cell cytotoxicity, antitumor activity, and survival rate in lung cancer bearing nude mice were analyzed.

RESULTS

IPN microparticles maintained AuP bioactivity against lung cancer cells (NCI-H460). In vivo study showed no observable systemic toxicity in nude mice bearing NCI-H460 xenografts after intravenous injection of 6 mg/kg AuP formulated with IPN microparticles. An anti-tumor activity level comparable to free AuP was maintained. Mice treated with 6 mg/kg AuP in IPN microparticles showed 100% survival rate while the survival rate of mice treated with free AuP was much less. Furthermore, microparticle-formulated AuP significantly reduced the intratumoral microvasculature when compared with the control.

CONCLUSION

AuP in IPN microparticles can reduce the systemic toxicity of AuP without compromising its antitumor activity. This work highlighted the potential application of AuP in IPN microparticles for anticancer chemotherapy.

Shape mediated splenotropic delivery of buparvaquone loaded solid lipid nanoparticles

Buparvaquone (BPQ)-loaded asymmetric solid lipid nanoparticles (SLN) prepared by a modified nanoprecipitation method were evaluated for splenotropic drug delivery. BPQ SLN exhibited an average particle size of 650.28 ± 6.75 nm with polydispersity index ≤ 0.3, entrapment efficiency of 96.57 ± 0.190%, and drug loading of 24.63 ± 0.042%. Scanning electron microscopy (SEM) revealed elongated particles with flattened and rounded edges. Aspect ratio, an important determinant of asymmetricity of the BPQ SLN, measured as the ratio of average length (1143 ± 0.083 nm) to width (419 ± 0.031 nm) was found to be 2.727 ± 0.19. The hemolytic potential of 10.86 ± 0.04% and good serum stability suggested feasibility for intravenous administration. ^99mTc-labeled BPQ SLN revealed high radiolabeling efficiency (> 95%) and good stability. Intravenous administration in mice revealed > 75% accumulation in the reticuloendothelial system organs. The percent radioactivity per gram of organ was in the order spleen > kidney > lungs > liver > lymph nodes, with high splenic accumulation and significantly lower concentration in the liver. An astoundingly high spleen/liver ratio with a maximum of 11.94 ± 1.37 at 3 h, which confirmed high splenic uptake is attributed to Kupffer cell bypass. Other factors contributing to splenotropy are the rigidity and the low molecular weight of the lipid in the BPQ SLN which enabled translocation of the particles into the splenic pulp. Our study proposes asymmetric BPQ SLN as a promising splenotropic delivery system for improved efficacy in theileriosis, a spleen resident infection.

Surface-modified polymeric nanoparticles for drug delivery to cancer cells

INTRODUCTION

The utilization of polymeric nanoparticles, as drug payloads, has been extensively prevailed in cancer therapy. However, the precise distribution of these nanocarriers is restrained by various physiological and cellular obstacles. Nanoparticles must avoid nonspecific interactions with healthy cells and in vivo compartments to circumvent these barriers. Since in vivo interactions of nanoparticles are mainly dependent on surface properties of nanoparticles, efficient control on surface constituents is necessary for the determination of nanoparticles' fate in the body.

AREAS COVERED

In this review, the surface-modified polymeric nanoparticles and their utilization in cancer treatment were elaborated. First, the interaction of nanoparticles with numerous in vivo barriers was highlighted. Second, different strategies to overcome these obstacles were described. Third, some inspiring examples of surface-modified nanoparticles were presented. Later, fabrication and characterization methods of surface-modified nanoparticles were discussed. Finally, the applications of these nanoparticles in different routes of treatments were explored.

EXPERT OPINION

Surface modification of anticancer drug-loaded polymeric nanoparticles can enhance the efficacy, selective targeting, and biodistribution of the anticancer drug at the tumor site.

Acid-sensitive PEGylated paclitaxel prodrug nanoparticles for cancer therapy: Effect of PEG length on antitumor efficacy

Paclitaxel is one of the most widely used anticancer agents, but strong side effects and low bioavailability limit its clinical efficacy. The use of tumor microenvironment-responsive prodrugs is promising to solve these problems, and a smart linkage is crucial to achieve the efficient release of paclitaxel from such prodrugs in tumor. Herein, an acid-responsive acetone-based acyclic ketal linkage is used to construct paclitaxel prodrugs with different length of poly(ethylene glycol) (PEG). The PEGylated acetone-based acyclic-ketal-linked prodrugs of paclitaxel (PKPs) self-assembled into nanoparticles that were stable in normal physiological environment but released paclitaxel rapidly in mildly acidic environment in tumor. The length of PEG had considerable impact on size and critical micelle concentration of PKP nanoparticles, thereby affecting prodrug hydrolysis kinetics, pharmacokinetics, biodistribution, and antitumor activity for PKP nanoparticles. In an A2780 xenograft mouse model, PKP nanoparticles displayed improved pharmacokinetics and superior antitumor efficacy against Taxol. Our results demonstrate that acyclic-ketal-based prodrugs are useful for the development of acid-responsive anticancer nanomedicines.

Nanomaterials and Innate Immunity: A Perspective of the Current Status in Nanosafety

Human exposure to engineered nanomaterials (ENMs) is inevitable due to the plethora of applications for which they are being manufactured and integrated within. ENMs demonstrate plentiful advantages in terms of industrial approaches as well as from a consumer perspective. However, despite such positives, doubts remain over the human health implications of ENM exposure. In light of the increased research focus upon the potential effects of ENM exposure to human health in recent decades, questions still remain regarding the safety of these highly advanced, precision-tuned physical entities. The risk of short-term, high-dose exposure to humans is considered relatively low, although this has formed the direction of the hazard-assessment community since the turn of the 21st century. However, the possibility of humans being exposed repeatedly over a long period of time to a low-dose of ENMs of varying physicochemical characteristics is of significant concern, and thus, industry, government, academic, and consumer agencies are only now beginning to consider this. Notably, when considering the human health implications of such low-dose, long-term, repeated exposure scenarios, the impact of ENMs upon the human immune system is of primary importance. However, there remains a real need to understand the impact of ENMs upon the human immune system, especially the innate immune system, at all stages of life, given exposure to nanosized particles begins before birth, that is, of the fetus. Therefore, the purpose of this perspective is to summarize what is currently known regarding ENM exposure of different components of the innate immune system and identify knowledge gaps that should be addressed if we are to fully deduce the impact of ENM exposure on innate immune function.

Stealth Coating of Nanoparticles in Drug-Delivery Systems

Nanoparticles (NPs) have emerged as a powerful drug-delivery tool for cancer therapies to enhance the specificity of drug actions, while reducing the systemic side effects. Nonetheless, NPs interact massively with the surrounding physiological environments including plasma proteins upon administration into the bloodstream. Consequently, they are rapidly cleared from the blood circulation by the mononuclear phagocyte system (MPS) or complement system, resulting in a premature elimination that will cause the drug release at off-target sites. By grafting a stealth coating layer onto the surface of NPs, the blood circulation half-life of nanomaterials can be improved by escaping the recognition and clearance of the immune system. This review focuses on the basic concept underlying the stealth behavior of NPs by polymer coating, whereby the fundamental surface coating characteristics such as molecular weight, surface chain density as well as conformations of polymer chains are of utmost importance for efficient protection of NPs. In addition, the most commonly used stealth polymers such as poly(ethylene glycol) (PEG), poly(2-oxazoline) (POx), and poly(zwitterions) in developing long-circulating NPs for drug delivery are also thoroughly discussed. The biomimetic strategies, including the cell-membrane camouflaging technique and CD47 functionalization for the development of stealth nano-delivery systems, are highlighted in this review as well.

Modular Acid-Activatable Acetone-Based Ketal-Linked Nanomedicine by Dexamethasone Prodrugs for Enhanced Anti-Rheumatoid Arthritis with Low Side Effects

Given the physically encapsulated payloads with drug burst release and/or low drug loading, it is critical to initiate an innovative prodrug strategy to optimize the design of modular nanomedicines. Here, we designed modular pH-sensitive acetone-based ketal-linked prodrugs of dexamethasone (AKP-dexs) and formulated them as nanoparticles. We comprehensively studied the relationships between AKP-dex structure and properties, and we selected two types of AKP-dex-loaded nanoparticles for in vivo studies on the basis of their size, drug loading, and colloidal stability. In a collagen-induced arthritis rat model, these AKP-dex-loaded nanoparticles showed higher accumulation in inflamed joints and better therapeutic efficacy than free dexamethasone phosphate with less-severe side effects. AKP-dex-loaded nanoparticles may be useful for treating other inflammatory diseases and thus have great translational potential. Our findings represent an important step toward the development of practical applications for acetone-based ketal-linked prodrugs and are useful in the design of modular nanomedicines.

Gelatin nanoparticles for NSAID systemic administration: Quality by design and artificial neural networks implementation

The present study evaluates the preparation of systemic administrated NSAID gelatin nanoparticles with the aid of quality by design and artificial neural networks (ANNs). Specifically, two different preparation techniques (i.e. nanoprecipitation and two-step desolvation) were implemented for the formulation of diclofenac sodium (DLC) gelatin nanoparticles (GNs). Preliminary screening experiments showed that in the case of nanoprecipitation the best compromise (in terms of achieving both small particle size and high encapsulation efficiency) was the use of poloxamer 407 (as stabilizer) and acetone (as non-solvent), while in the case of two-step desolvation significant effect had the use of acetone, gelatin type and bloom number (type B with bloom 150 was selected for further evaluation). Implementation of a central composite experimental design (CCD), showed that in the case of nanoprecipitation the optimum formulation can be achieved at high poloxamer, high gelatin and moderate to high glutaraldehyde (GTA used for crosslinking) concentrations, while in the case of two-step desolvation high gelatin and GTA concentrations are needed. Artificial neural networks (ANN) implementation showed significantly improved prediction ability compared to MLR, while verification experiments showed good agreement between the ANN predicted and the experimentally obtained results. SEM analysis of the optimum suggested formulations showed nanoparticles with smooth surface, while powder X-ray diffraction (XRD) analysis showed the formation of amorphously dispersed systems, and Fourier transform infrared spectroscopy (FTIR) revealed the presence of molecular interactions irrespectively of the preparation method followed. A slightly faster release profile was observed in the case of nanoprecipitation based GNs, while all formulations followed biphasic release profile.

Surface Functionalization of Pegylated Gold Nanoparticles with Antioxidants Suppresses Nanoparticle-Induced Oxidative Stress and Neurotoxicity

Because of their biocompatibility and biosafety, pegylated Au NPs (Au@PEG), as a nanodrug-carrier, have been widely applied in different biomedical applications, including imaging and drug delivery systems. Under such conditions, the biosafety of Au@PEG has attracted tremendous attention. However, only a small number of studies focused on the neurotoxicity of Au@PEG used as drug delivery carriers not to mention reducing the neurotoxicity of Au@PEG. To address this issue, the adverse effects of Au@PEG on human neuroblastoma SHSY5Y cells were first investigated. The results showed that 4.5 nm Au@PEG significantly induced cell apoptosis through upregulating reactive oxygen species (ROS) production and disordering the mitochondrial membrane potential. To further evaluate whether the neurotoxicity of Au@PEG could be improved through conjugating antioxidants on the surface of Au@PEG, Trolox (a vitamin E analogue)-functionalized Au@PEG (Au@Trolox) was synthesized. The results showed that the neurotoxicity of Au@PEG on SHSY5Y cells could be significantly improved by Au@Trolox. Next, mice were subjected to administration of 4.5 nm Au@PEG and Au@Trolox for 3 months. An increase of oxidative stress and a decrease in the activity of key antioxidant enzymes including glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and catalase (CAT) were observed after long-term injection of Au@PEG. More importantly, both the apoptosis of neurons and the activation of astrocytes were observed in the hippocampus of mice injected with Au@PEG. In contrast, the adverse effects of Au@PEG could be improved when injected with Au@Trolox. In short, the present study provided new insights into the toxicity evaluation of nanoparticles and would help to better understand and prevent the neurotoxicity of nanomaterials used in pharmaceutics.

Clickable modular polysaccharide nanoparticles for selective cell-targeting

A therapeutic nanocarrier capable of cell targeting has the potential to reduce off-target effects of otherwise effective drugs. Nanoparticle surface modification can be tailored for specific cells, however multistep surface modification can prove slow and difficult for a variety of cell types. Here, we designed drug carrying polysaccharide based nanoparticles with a layered structure for clickable surface modification. The center of nanoparticle was composed of cationic macromer (e.g., poly-l-lysine) and anionic polysaccharide (e.g., heparin). Furthermore, a 'clickable' polysaccharide was installed on the surface of the nanoparticles to permit a wide range of bioconjugation via norbornene-tetrazine click chemistry. The utilities of these layered nanoparticles were demonstrated via enhanced protein sequestration, selective cell targeting (via PEGylation or altering polysaccharide coating), as well as loading and release of chemotherapeutic. The drug-loaded nanocarriers proved cytotoxic to J774A.1 monocytes and MOLM-14 leukemia cells.

Preparation of PEG-grafted chitosan/streptokinase nanoparticles to improve biological half-life and reduce immunogenicity of the enzyme

Streptokinase, as a thrombolytic drug, is widely used in treatment of cardiovascular disorders and deep vein thrombosis. Streptokinase is immunogenic due to its prokaryotic source, having short biological half-life (i.e. 15 to 30 min) that is not enough for an efficient therapy. In this study, nanoparticles (NPs) of chitosan/streptokinase and polyethylene glycol (PEG)-grafted chitosan/streptokinase were prepared by polyelectrolyte complex method. Particle size of chitosan and PEG-grafted chitosan NPs were 154 ± 42 and 211 ± 47 nm, respectively. Results showed that using PEG in preparation of nanoparticles leads to ~24% decrease in encapsulation efficiency. Encapsulation of streptokinase in the NPs also resulted in a slight reduction in enzymatic activity. However, in vivo findings indicated that response of the immune system was delayed for 20 days and blood circulation time of the enzyme increased up to 120 min by using PEG. Biological half-life of the drug also increased up to twice in PEG-grafted chitosan. In conclusion, PEG-grafted chitosan NPs could be an alternative for delivery of streptokinase to reduce its clinical limitations.

Sub-10 nm Theranostic Unimolecular Micelles with High Tumor-Specific Accumulation, Retention, and Inhibitory Effect

Theranostic agents that integrate far-red/near-infrared fluorescence and anticancer drugs are useful for biomedical applications such as imaging-guided therapy of cancers. However, the clinical translation of previously reported theranostic agents is still limited by factors such as weak fluorescence of the imaging probe, premature and off-target release of fluorophores and drugs during blood circulation, the long-term retention in the reticuloendothelial system, and side effects of toxicity. Here, we report a new type of ultrasmall theranostic unimolecular micelles with an average diameter below 10 nm, and dual functionalities of bright fluorescence in the spectral window of 600-800 nm toward noninvasive in vivo bioimaging and covalently bound anticancer drugs for specific cancer treatment. Each unimolecular micelle is formed by an amphiphilic bottlebrush copolymer containing a fluorescent conjugated backbone of poly(fluorene-alt-(4,7-bis(hexylthien)-2,1,3-benzothiadiazole)), from which hydrophobic disulfide-linked camptothecin as an anticancer drug and hydrophilic oligo(ethylene glycol) are grafted. These ultrasmall unimolecular micelles exhibit remarkably high efficiency of accumulation and retention in tumor tissues with a tumor inhibitory rate of 50%, but little distribution in other healthy organs and tissues. Such a feature of enhanced tumor targeting and reduced toxic side effects against healthy cells and tissues is promising for future clinical translation of imaging-guided cancer therapy.

Pegylated magnetic mesoporous silica nanoparticles decorated with AS1411 Aptamer as a targeting delivery system for cytotoxic agents

Fulfilling the purpose of developing a NP with theragnostic capabilities, the current study describes the synthesis of an aptamer-functionalized PEG-coated SPION/mesoporous silica core-shell nanoparticle for concurrent cancer targeted therapy and magnetic resonance imaging. SPIONs were synthesized according to a thermal decomposition method and served as cores for SPION/mesoporous silica core/shell nanoparticles (MMSNs). Doxorubicin was then successfully loaded in MMSNs which were then coated with di-carboxylic acid functionalized polyethylene glycol (PEG-MMSNs). AS1411 aptamers were at the end covalently attached to NPs (APT-PEG-MMSNs). The mean diameter of synthesized NPs was about 89 nm and doxorubicin encapsulation efficacy was ≈67.47%. Results of MTT based cell cytotoxicity assay demonstrated a significantly higher toxicity profile for APT-PEG-MMSNs against MCF7 cells compared to non-decorated MMSNs, while no significant differences were spotted against NIH-3T3 cells. Meanwhile, formation of protein corona around APT-PEG-MMSNs in biological medium significantly attenuated observed cytotoxicity against MCF7 cell line. Examining NPs uptake by MCF7 cells using confocal laser scanning microscopy also confirmed superiority of APT-PEG-MMSNs over PEG-MMSNs. Finally, APT decorated NPs induced highest signal intensity reduction in T₂-weighted images during in vitro MRI assay. In conclusion, developed NPs may serve as promising multifunctional vehicles for simultaneous cancer targeted therapy and MRI imaging.

Influence of PEGylation on PLGA nanoparticle properties, hydrophobic drug release and interactions with human serum albumin

Objective

To evaluate the impact of PEG content on poly(lactic-co-glycolic acid) (PLGA) NP physicochemical properties, hydrophobic drug release (rifampicin as a model drug) and human serum protein binding.

Methods

Rifampicin loaded and unloaded nanoparticles with PEG content of 0–17% (w/w) were prepared by an emulsification–evaporation technique. Nanoparticles were characterized for size, zeta potential and morphology. PEGlyation was confirmed using proton nuclear magnetic resonance (1H NMR). Fluorescence spectroscopy and dynamic light scattering were used to determine nanoparticle-protein binding, binding constants and stability of nanoparticles in human serum, respectively. Drug loading and release were determined by UV-VIS spectroscopy and drug release data was mathematically modelled.

Key findings

A NP PEG content of 17% w/w significantly retarded release of rifampicin from PLGA NPs and altered kinetics of drug release. Stern–Volmer (Ksv) protein binding constants decreased upon PEG incorporation. A 2% w/w PEG was sufficient to significantly reduce protein binding extent to PLGA NPs and maintain particle size distributions.

Conclusion

The ability to fine tune drug release and formation of protein corona around nanoparticles is crucial to formulation scientists. This study suggests that PLGA NPs with low PEG content might be suitable for extended circulation and rapid drug release and that higher PEG content retards hydrophobic drug release.

Recent Technological Advances in the Mass Spectrometry-based Nanomedicine Studies: An Insight from Nanoproteomics

Nanoscience becomes one of the most cutting-edge research directions in recent years since it is gradually matured from basic to applied science. Nanoparticles (NPs) and nanomaterials (NMs) play important roles in various aspects of biomedicine science, and their influences on the environment have caused a whole range of uncertainties which require extensive attention. Due to the quantitative and dynamic information provided for human proteome, mass spectrometry (MS)-based quantitative proteomic technique has been a powerful tool for nanomedicine study. In this article, recent trends of progress and development in the nanomedicine of proteomics were discussed from quantification techniques and publicly available resources or tools. First, a variety of popular protein quantification techniques including labeling and label-free strategies applied to nanomedicine studies are overviewed and systematically discussed. Then, numerous protein profiling tools for data processing and postbiological statistical analysis and publicly available data repositories for providing enrichment MS raw data information sources are also discussed.

Nanoscale Lipophilic Prodrugs of Dexamethasone with Enhanced Pharmacokinetics

The encapsulation of glucocorticoids, such as dexamethasone, in nanoparticles (NPs) faces two main issues: a low drug loading and the destabilization of the nanoparticle suspension due to drug crystallization. Here, we successfully formulated a prodrug of dexamethasone, dexamethasone palmitate (DXP), into nanoparticles stabilized by the sole presence of distearoyl- sn-glycero-3-phosphoethanolamine- N-[methoxy(poly(ethylene glycol))-2000] (DSPE-PEG₂₀₀₀). Two formulation processes, nanoprecipitation and emulsion-evaporation, allowed the formation of stable nanoparticles. By adjusting the drug/lipid ratio and the DXP concentration, nanoparticles of DXP (DXP-NPs) with a size between 130 and 300 nm can be obtained. Owing to the presence of DSPE-PEG₂₀₀₀, a high drug entrapment efficiency of 98% w/w was reached for both processes, corresponding to a very high equivalent dexamethasone drug loading of around 50% w/w in the absence of crystallization upon storage at 4 °C. The anti-inflammatory activity of DXP-NPs was preserved when incubated with macrophages activated with lipopolysaccharide. Pharmacokinetics parameters were evaluated after intravenous (IV) injection of DXP-NPs to healthy mice. The release of DXM from DXP-NPs in plasma was clearly controlled up to 18 h compared with the free drug, which was rapidly eliminated from plasma after administration. In conclusion, a novel type of nanoparticle combining the advantages of prodrugs and nanoparticles was designed, easy to produce with a high loading efficiency and leading to modified pharmacokinetics and tissue distribution after IV administration.