Beauty is skin deep: a surface monolayer perspective on nanoparticle interactions with cells and bio-macromolecules

Autophagy in cancer immunotherapy: Perspective on immune evasion and cell death interactions

Both the innate and adaptive immune systems work together to produce immunity. Cancer immunotherapy is a novel approach to tumor suppression that has arisen in response to the ineffectiveness of traditional treatments like radiation and chemotherapy. On the other hand, immune evasion can diminish immunotherapy's efficacy. There has been a lot of focus in recent years on autophagy and other underlying mechanisms that impact the possibility of cancer immunotherapy. The primary feature of autophagy is the synthesis of autophagosomes, which engulf cytoplasmic components and destroy them by lysosomal degradation. The planned cell death mechanism known as autophagy can have opposite effects on carcinogenesis, either increasing or decreasing it. It is autophagy's job to maintain the balance and proper functioning of immune cells like B cells, T cells, and others. In addition, autophagy controls whether macrophages adopt the immunomodulatory M1 or M2 phenotype. The ability of autophagy to control the innate and adaptive immune systems is noteworthy. Interleukins and chemokines are immunological checkpoint chemicals that autophagy regulates. Reducing antigen presentation to induce immunological tolerance is another mechanism by which autophagy promotes cancer survival. Therefore, targeting autophagy is of importance for enhancing potential of cancer immunotherapy.

Surface Bio-engineered Polymeric Nanoparticles

Surface bio-engineering of polymeric nanoparticles (PNPs) has emerged as a cornerstone in contemporary biomedical research, presenting a transformative avenue that can revolutionize diagnostics, therapies, and drug delivery systems. The approach involves integrating bioactive elements on the surfaces of PNPs, aiming to provide them with functionalities to enable precise, targeted, and favorable interactions with biological components within cellular environments. However, the full potential of surface bio-engineered PNPs in biomedicine is hampered by obstacles, including precise control over surface modifications, stability in biological environments, and lasting targeted interactions with cells or tissues. Concerns like scalability, reproducibility, and long-term safety also impede translation to clinical practice. In this review, these challenges in the context of recent breakthroughs in developing surface-biofunctionalized PNPs for various applications, from biosensing and bioimaging to targeted delivery of therapeutics are discussed. Particular attention is given to bonding mechanisms that underlie the attachment of bioactive moieties to PNP surfaces. The stability and efficacy of surface-bioengineered PNPs are critically reviewed in disease detection, diagnostics, and treatment, both in vitro and in vivo settings. Insights into existing challenges and limitations impeding progress are provided, and a forward-looking discussion on the field's future is presented. The paper concludes with recommendations to accelerate the clinical translation of surface bio-engineered PNPs.

Interfacing Nanomaterials with Biology through Ligand Engineering

Nanoparticles (NPs) have incredible potential in biology and biomedicine. Gold nanoparticles (AuNPs) have become a cornerstone of the nanomedicine revolution due to their ease of synthesis, inertness, and versatility. The widespread use of AuNPs can be traced to the development of accessible, bottom-up wet synthesis methods that emphasized the role of ligands in controlling the size, dispersity, and stability of colloids in solution. Decoration of AuNPs with organic ligands can be used to dictate the interactions of these nanomaterials with biosystems on multiple scales. The tunability of the AuNP ligand monolayer via covalent and noncovalent approaches allows the use of AuNPs in a broad range of biomedical fields.In this Account, we describe our use of AuNPs to answer a central question in the ligand engineering of colloidal nanoparticles: can we fabricate NPs that are nontoxic, modular, and functional in biological environments? We explored spherical AuNPs of different sizes and ligand structures, empirically exploring the AuNP-biomolecule interaction. We show here how the atom-by-atom control provided by organic synthesis can be used to create engineered ligands. Presenting these ligands on the surface of AuNPs creates multivalent constructs with unique and useful properties. Ligand design is a key feature of these AuNPs. We have developed ligands that have three distinct structural segments: 1) a hydrophobic alkanethiol interior that imparts stability; 2) a tetra(ethylene glycol) segment that creates a noninteracting tabula rasa surface; and 3) ligand headgroups that dictate how the AuNP interacts with the outside world. Our research into the design principles of ligands on AuNPs and their interactions with biological systems can be translated to other nanoparticle systems.This Account also summarizes the trajectory of ligand engineering in our laboratory and further afield. At the outset, experimental and theoretical fundamental studies were focused on the interactions between AuNPs and cellular components, such as proteins and lipid membranes. Understanding these behaviors provided the direction for investigating how ligands mediate the interface of AuNPs with mammalian and bacterial cells. In these experiments, it was particularly noteworthy that the ligand hydrophobicity and charge play a significant role in the uptake and toxicity of AuNPs. These revelations formed a basis for translating AuNPs to physiological environments. We present how we have integrated our synthetic abilities to construct AuNPs for biomedical applications, including delivery, bioorthogonal catalysis, antimicrobial and antitumor therapeutics, and biosensing.Overall, we hope that this Account will give the reader insight into how our research has evolved, changing AuNPs from synthetic curiosities into functional nanoplatforms for nanomedicine, all through the power of ligand design and synthesis.

A General One-Step Synthesis of Alkanethiyl-Stabilized Gold Nanoparticles with Control over Core Size and Monolayer Functionality

In spite of widespread interest in the unique size-dependent properties and consequent applications of gold nanoparticles (AuNPs), synthetic protocols that reliably allow for independent tuning of surface chemistry and core size, the two critical determinants of AuNP properties, remain limited. Often, core size is inherently affected by the ligand structure in an unpredictable fashion. Functionalized ligands are commonly introduced using postsynthesis exchange procedures, which can be inefficient and operationally delicate. Here, we report a one-step protocol for preparing monolayer-stabilized AuNPs that is compatible with a wide range of ligand functional groups and also allows for the systematic control of core size. In a single-phase reaction using the mild reducing agent tert-butylamine borane, AuNPs that are compatible with solvents spanning a wide range of polarities from toluene to water can be produced without damaging reactive chemical functionalities within the small-molecule surface-stabilizing ligands. We demonstrate that the rate of reduction, which is easily controlled by adjusting the period over which the reducing agent is added, is a simple parameter that can be used irrespective of the ligand structure to adjust the core size of AuNPs without broadening the size distribution. Core sizes in the range of 2-10 nm can thus be generated. The upper size limit appears to be determined by the nature of each specific ligand/solvent pairing. This protocol produces high quality, functionally sophisticated nanoparticles in a single step. By combining the ability to vary size-related nanoparticle properties with the option to incorporate reactive functional groups at the nanoparticle-solvent interface, it is possible to generate chemically reactive colloidal building blocks from which more complex nanoparticle-based devices and materials may subsequently be constructed.

Nanotherapeutics in autophagy: a paradigm shift in cancer treatment

Autophagy is a catabolic process in which an organism responds to its nutrient or metabolic emergencies. It involves the degradation of cytoplasmic proteins and organelles by forming double-membrane vesicles called "autophagosomes." They sequester cargoes, leading them to degradation in the lysosomes. Although autophagy acts as a protective mechanism for maintaining homeostasis through cellular recycling, it is ostensibly a cause of certain cancers, but a cure for others. In other words, insufficient autophagy, due to genetic or cellular dysfunctions, can lead to tumorigenesis. However, many autophagy modulators are developed for cancer therapy. Diverse nanoparticles have been documented to induce autophagy. Also, the highly stable nanoparticles show blockage to autophagic flux. In this review, we revealed a general mechanism by which autophagy can be induced or blocked via nanoparticles as well as several studies recently performed to prove the stated fact. In addition, we have also elucidated the paradoxical roles of autophagy in cancer and how their differential role at different stages of various cancers can affect its treatment outcomes. And finally, we summarize the breakthroughs in cancer disease treatments by using metallic, polymeric, and liposomal nanoparticles as potent autophagy modulators.

Nanocarriers: A Reliable Tool for the Delivery of Anticancer Drugs

Nanomedicines have gained popularity due to their potential therapeutic applications, especially cancer treatment. Targeted nanoparticles can deliver drugs directly to cancer cells and enable prolonged drug release, reducing off-target toxicity and increasing therapeutic efficacy. However, translating nanomedicines from preclinical to clinical settings has been difficult. Rapid advancements in nanotechnology promise to enhance cancer therapies. Nanomedicine offers advanced targeting and multifunctionality. Nanoparticles (NPs) have several uses nowadays. They have been studied as drug transporters, tumor gene delivery agents, and imaging contrast agents. Nanomaterials based on organic, inorganic, lipid, or glycan substances and synthetic polymers have been used to enhance cancer therapies. This review focuses on polymeric nanoparticle delivery strategies for anticancer nanomedicines.

Histopathological evaluation of amino acid capped silver nanoconjugates in albino mice

Various molecules may modify the surface chemistry of commonly used nanomaterials (NMs), resulting in the synthesis of novel and safer NMs. The current study was delineated to evaluate the in vivo toxicity profiling of the silver nanoconjugates (AgNCs) conjugated with different amino acids. The L-glycine capped-AgNCs exhibited toxicity and caused tissue damage, while L-cystine- and L-tyrosine-capped AgNCs showed protective effects against cadmium-induced toxicity. L-cystine-capped AgNCs performed well as compared to other amino-acid AgNCs. The level of serum creatinine, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase and blood urea increased (p < 0.05) in G2, G3 and G5 in comparison to G1 (control group), while an increase in bilirubin for G2 was statistically non-significant (p > 0.05). The ALT and AST elevated (p < 0.05) in G4; however, other serological parameters in G4 and G6 did not show any noticeable change in their values. Histological analysis showed disturbed and deformed cellular structures in liver and kidney tissues of G2, G3 and G5. However, G4 and G6 samples demonstrated minute changes in comparison to G1. It is concluded that L-cystine- and L-tyrosine-capped AgNCs exhibited protective effects and should be tested further for developing safer nanoconjugates for biomedical uses.

Solid Lipid Nanoparticles as Carriers of Natural Phenolic Compounds

Phenolic compounds are one of the most widespread classes of compounds in nature, with several beneficial biological effects being associated with their anti-oxidant and anti-carcinogenic activities. Their application in the prevention or treatment of numerous chronic diseases have been studied, but a major drawback is still the low bioavailability of these compounds, as well as their instability towards pH, temperature, and light in some cases. Nanotechnology has emerged as an alternative to overcome these limitations, and the use of lipidic encapsulation systems is a promising technique to achieve an efficient drug delivery, protecting molecules from external factors and improving their bioavailability. In this review, solid lipid nanoparticles and nanostructured lipid carriers are highlighted as an important tool for the improvement of the bioavailability and stability of natural phenolic compounds, including their preparation methods and functionalization approaches and the discussion of several applications for putative use in cosmetic and pharmacologic products.

Assisted delivery of anti-tumour platinum drugs using DNA-coiling gold nanoparticles bearing lumophores and intercalators: towards a new generation of multimodal nanocarriers with enhanced action

New gold and lipoic based nanocarriers for the delivery of platinum(ii) and platinum(iv) drugs are developed, which allow enhanced loading of the drug on the surface of the nanocarriers and release in a pH-dependent fashion, with superior release at lower pHs which are associated with many tumours. The conjugate nanoparticles and their conjugates enter cells rapidly (within 3 hours). They tend to cluster in vesicles and are also observed by light and electron microscopies in the cytoplasm, endoplasmic reticulum and nucleus. We further incorporate aminoanthraquinone units that are both fluorophores and DNA intercalators. This results in nanocarriers that after drug release will remain surface decorated with DNA-binders challenging the conventional design of the nanocarrier as an inert component. The outcome is nanocarriers that themselves have distinctive, remarkable and unusual DNA binding properties being able to bind and wrap DNA (despite their anionic charge) and provide enhanced cytotoxic activity beyond that conferred by the platinum agents they release. DNA coiling is usually associated with polycations which can disrupt cell membranes; anionic nanoparticles that can cause novel and dramatic effects on DNA may have fascinating potential for new approaches to in-cell nucleic acid recognition. Our findings have implications for the understanding and interpretation of the biological activities of nanoparticles used to deliver other DNA-binding drugs including clinical drug doxorubicin and its formulations.

Protein-Engineered Functional Materials

Proteins are versatile macromolecules that can perform a variety of functions. In the past three decades, they have been commonly used as building blocks to generate a range of biomaterials. Owing to their flexibility, proteins can either be used alone or in combination with other functional molecules. Advances in synthetic and chemical biology have enabled new protein fusions as well as the integration of new functional groups leading to biomaterials with emergent properties. This review discusses protein-engineered materials from the perspectives of domain-based designs as well as physical and chemical approaches for crosslinked materials, with special emphasis on the creation of hydrogels. Engineered proteins that organize or template metal ions, bear noncanonical amino acids (NCAAs), and their potential applications, are also reviewed.

Active Ester Containing Surfmer for One-Stage Polymer Nanoparticle Surface Functionalization in Mini-Emulsion Polymerization

Functional surface active monomers (surfmers) are molecules that combine the functionalities of surface activity, polymerizability, and reactive groups. This study presents an improved pathway for the synthesis of the active ester containing surfmer p-(11-acrylamido)undecanoyloxyphenyl dimethylsulfonium methyl sulfate (AUPDS). Further, the preparation of poly(methyl methacrylate) and polystyrene nanoparticles (NPs) by mini-emulsion polymerization using AUPDS is investigated, leading to NPs with active ester groups on their surface. By systematically varying reaction parameters and reagent concentrations, it was found that AUPDS feed concentrations between 2⁻4 mol% yielded narrowly distributed and stable spherical particles with average sizes between 83 and 134 nm for non-cross-linked NPs, and up to 163 nm for cross-linked NPs. By basic hydrolysis of the active ester groups in aqueous dispersion, the positive ζ-potential (ZP) was converted into a negative ZP and charge quantities determined by polyelectrolyte titrations before and after hydrolysis were in the same range, indicating that the active ester groups were indeed accessible in aqueous suspension. Increasing cross-linker amounts over 10 mol% also led to a decrease of ZP of NPs, probably due to internalization of the AUPDS during polymerization. In conclusion, by using optimized reaction conditions, it is possible to prepare active ester functionalized NPs in one stage using AUPDS as a surfmer in mini-emulsion polymerization.

Anomalous Vascular Dynamics of Nanoworms within Blood Flow

Nanomaterials have been widely used in the design of drug delivery platforms. This work computationally explores the vascular dynamics of nanoworms as drug carriers within blood flow by considering the effects of nanoworm length, stiffness, and local physiological conditions such as hematocrit. We found that nanoworms with length of 8 μm and moderate stiffness are the optimal choice as drug carriers for circulating within normal vascular network due to their lower near wall margination. Compared to those of spherical rigid particles, these nanoworms demonstrate significant demargination behaviors at hematocrit 20%, induced by the local hydrodynamic interactions. Specifically, the interactions between nanoworms and red blood cells create asymmetrical local flow fields, resulting in the demargination of nanoworms. In addition, the flexibility of nanoworms enables them to conform to the deformed shape of red blood cells under shear flow, leading to their high concentration within the core region of vessels. Therefore, the long blood circulation time of nanoworms can be partially attributed to their demargination behaviors and intertwinement with red blood cells. According to these simulation results, tuning the length and stiffness of nanoworms is the key to design drug carries with reduced near wall margination within normal vascular networks and extend their blood circulation time.

Continuum tuning of nanoparticle interfacial properties by dynamic covalent exchange

Dynamic covalent modification of the surface-stabilizing monolayer accesses a continuum of nanoparticle properties from a single starting point.

Surface chemical composition is fundamental to determining properties on the nanoscale, making precise control over surface chemistry critical to being able to optimise nanomaterials for virtually any application. Surface-engineering independent of the preparation of the underlying nanomaterial is particularly attractive for efficient, divergent synthetic strategies, and for the potential to create reactive, responsive and smart nanodevices. For monolayer-stabilised nanoparticles, established methods include ligand exchange to replace the ligand shell in its entirety, encapsulation with amphiphilic (macro)molecules, noncovalent interactions with surface-bound biomolecules, or a relatively limited number of covalent bond forming reactions. Yet, each of these approaches has considerable drawbacks. Here we show that dynamic covalent exchange at the periphery of the nanoparticle-stabilizing monolayer allows surface-bound ligand molecular structure to be substantially modified in mild and reversible processes that are independent of the nanoparticle–molecule interface. Simple stoichiometric variation allows the extent of exchange to be controlled, generating a range of kinetically stable mixed-monolayer compositions across an otherwise identical, self-consistent series of nanoparticles. This approach can be used to modulate nanoparticle properties that are defined by the monolayer composition. We demonstrate switching of nanoparticle solvent compatibility between widely differing solvents – spanning hexane to water – and the ability to tune solubility across the entire continuum between these extremes, all from a single nanoparticle starting point. We also demonstrate that fine control over mixed-monolayer composition influences the assembly of discrete, colloidally stable nanoparticle clusters. By carefully assessing monolayer composition in each state, using both in situ and ex situ methods, we are able to correlate the molecular-level details of the nanoparticle-bound monolayer with system-level properties and behaviour. These empirically determined relationships contribute fundamental insights on nanoscale structure–function relationships, which are currently beyond the capabilities of ab initio prediction.

Folate-conjugated and pH-responsive polymeric micelles for target-cell-specific anticancer drug delivery

In this study, we developed a folate (FA)-conjugated and pH-responsive active targeting micellar system for anti-cancer drug delivery. In this system, FA was attached to the terminal of the hydrophilic segment of poly(lactic acid)-poly(L-lysine) (PLA-PLL), and PLL was modified by a citric acid group. The FA receptor-mediated active targeting and electrostatic interaction between micelles and cell membrane due to a negative-to-positive charge reversal was combined in one micellar anti-cancer drug delivery system to enhance the tumour targeting and cellular internalisation of micelles. In vitro and in vivo anti-cancer studies demonstrated that the doxorubicin-loaded, FA-conjugated and pH-responsive polymeric micelles possess an enhanced and effective cancer efficiency.

STATEMENT OF SIGNIFICANCE

Negatively charged nano-carriers prolonged anti-cancer drugs' blood circulation. However it is difficult to be internalised. Therefore, a negative-to-positive charged micelle surface could improve selectivity for tumour cells and increase uptake chance. In this study, we developed a folate (FA)-conjugated and pH-responsive active targeting micellar system for anti-cancer drug delivery. The FA receptor-mediated active targeting and electrostatic interaction between micelles and cell membrane due to a negative-to-positive charge reversal was combined in one micellar anti-cancer drug delivery system to enhance the tumour targeting and cellular internalisation of micelles. In vitro and in vivo anti-cancer studies demonstrated that the doxorubicin-loaded, FA-conjugated and pH-responsive polymeric micelles possess an enhanced and effective cancer efficiency.

Role of Surface Hydrophobicity of Dicationic Amphiphile-Stabilized Gold Nanoparticles on A549 Lung Cancer Cells

Herein, we report the surface functionality of dicationic cysteamine conjugated cholic acid (DCaC), dicationic cysteamine conjugated deoxycholic acid (DCaDC), and dicationic cysteamine conjugated lithocholic acid (DCaLC) templated gold nanoparticles (AuNPs) on mammalian cells. The haemocompatibility of the synthesized NPs was evaluated by in vitro hemolysis and erythrocyte sedimentation rate using human red blood cells (RBCs). In all of the systems, no toxicity was observed on human erythrocytes (RBCs) up to the concentration of 120 μg/mL. The anticancer activity of these dicationic amphiphile-stabilized AuNPs on A549 lung cancer cells was demonstrated by in vitro cell viability assay, intracellular reactive oxygen species estimation by DCFH-DA, apoptosis analysis using AO-EtBr fluorescence staining, DNA fragmentation analysis by agarose gel electrophoresis, and western blot analysis of caspase-3 expression. These results suggest that the cytotoxicity of AuNPs to A549 cells increase with the dose and hydrophobicity of amphiphiles and were found to be in the order: DCaLC-AuNPs > DCaDC-AuNPs > DCaC-AuNPs.

Dermal and transdermal delivery of pharmaceutically relevant macromolecules

The skin offers an attractive way for dermal and transdermal drug delivery that is why the drug still needs certain qualities to transcend the outermost layer of the skin, the stratum corneum. The requirements are: drugs with a maximum molecular weight of 1kDa, high lipophilicity and a certain polarity. This would restrict the use of a transdermal delivery of macromolecules, which would make the drug more effective in therapeutic administration. Various studies have shown that macromolecules without support do not penetrate the human skin. This effect can be achieved using physical and chemical methods, as well as biological peptides. The most popular physical method is the use of microneedles to create micropores in the skin and release the active agent in different sections. But also, other methods have been tested. Microjets, lasers, electroporation, sonophoresis and iontophoresis are also promising methods to successfully deliver dermal and transdermal macromolecules. Additionally, there are different penetration enhancer groups and biological peptides, which are also considered to be interesting approaches of enabling macromolecules to travel along the skin. All these methods will be described and evaluated in this review article.

Electrostatically driven resonance energy transfer in "cationic" biocompatible indium phosphide quantum dots

Indium Phosphide Quantum Dots (InP QDs) have emerged as an alternative to toxic metal ion based QDs in nanobiotechnology. The ability to generate cationic surface charge, without compromising stability and biocompatibility, is essential in realizing the full potential of InP QDs in biological applications. We have addressed this challenge by developing a place exchange protocol for the preparation of cationic InP/ZnS QDs. The quaternary ammonium group provides the much required permanent positive charge and stability to InP/ZnS QDs in biofluids. The two important properties of QDs, namely bioimaging and light induced resonance energy transfer, are successfully demonstrated in cationic InP/ZnS QDs. The low cytotoxicity and stable photoluminescence of cationic InP/ZnS QDs inside cells make them ideal candidates as optical probes for cellular imaging. An efficient resonance energy transfer (E ∼ 60%) is observed, under physiological conditions, between the cationic InP/ZnS QD donor and anionic dye acceptor. A large bimolecular quenching constant along with a linear Stern-Volmer plot confirms the formation of a strong ground state complex between the cationic InP/ZnS QDs and the anionic dye. Control experiments prove the role of electrostatic attraction in driving the light induced interactions, which can rightfully form the basis for future nano-bio studies between cationic InP/ZnS QDs and anionic biomolecules.

Nanomedicines for renal disease: current status and future applications

Treatment and management of kidney disease currently presents an enormous global burden, and the application of nanotechnology principles to renal disease therapy, although still at an early stage, has profound transformative potential. The increasing translation of nanomedicines to the clinic, alongside research efforts in tissue regeneration and organ-on-a-chip investigations, are likely to provide novel solutions to treat kidney diseases. Our understanding of renal anatomy and of how the biological and physico-chemical properties of nanomedicines (the combination of a nanocarrier and a drug) influence their interactions with renal tissues has improved dramatically. Tailoring of nanomedicines in terms of kidney retention and binding to key membranes and cell populations associated with renal diseases is now possible and greatly enhances their localization, tolerability, and efficacy. This Review outlines nanomedicine characteristics central to improved targeting of renal cells and highlights the prospects, challenges, and opportunities of nanotechnology-mediated therapies for renal diseases.

Multifunctional and High Affinity Polymer Ligand that Provides Bio-Orthogonal Coating of Quantum Dots

We detail the design of hydrophilic metal-coordinating ligands and their use for the effective coating of luminescent quantum dots (QDs). The ligand design exploits the specific, reagent-free nucleophilic addition reaction of amine-modified molecules toward maleic anhydride to introduce several lipoic acid metal anchors, hydrophilic zwitterion moieties, and specific reactive groups along a poly(isobutylene-alt-maleic anhydride) (PIMA) chain. Tunable reactive groups tested in this study include azide, biotin, carboxyl, and amine. Cap exchange with these multilipoic acid ligands via a photochemical ligation strategy yields homogeneous QD dispersions that are colloidally stable over several biologically relevant conditions and for extended periods of time. The zwitterionic coating yields compact nanoparticle size and imparts nonsticky surface properties onto the QDs, preventing protein absorption. The introduction of a controllable number of reactive groups allows conjugation of the QDs to biomolecules via bio-orthogonal coupling chemistries including (1) attachment of the neurotransmitter dopamine to QDs via amine-isothiocyanate reaction to produce a platform capable of probing interactions with cysteine in proteins, based on charge transfer interactions; (2) self-assembly of biotinylated QDs with streptavidin-dye; and (3) ligation of azide-functionalized QDs to cyclooctyne-modified transferrin via copper-free click chemistry, used for intracellular delivery. This ligand design strategy can be used to prepare an array of metal-coordinating ligands adapted for coating other inorganic nanoparticles, including magnetic and plasmonic nanomaterials.

Noble Hybrid Nanostructures as Efficient Anti-Proliferative Platforms for Human Breast Cancer Cell

Nanomaterials have proven to possess great potential in biomaterials research. Recently, they have suggested considerable promise in cancer diagnosis and therapy. Among others, silicon (Si) nanomaterials have been extensively employed for various biomedical applications; however, the utilization of Si for cancer therapy has been limited to nanoparticles, and its potential as anticancer substrates has not been fully explored. Noble nanoparticles have also received considerable attention owing to unique anticancer properties to improve the efficiency of biomaterials for numerous biological applications. Nevertheless, immobilization and control over delivery of the nanoparticles have been challenge. Here, we develop hybrid nanoplatforms to efficiently hamper breast cancer cell adhesion and proliferation. Platforms are synthesized by femtosecond laser processing of Si into multiphase nanostructures, followed by sputter-coating with gold (Au)/gold-palladium (Au-Pd) nanoparticles. The performance of the developed platforms was then examined by exploring the response of normal fibroblast and metastatic breast cancer cells. Our results from the quantitative and qualitative analyses show a dramatic decrease in the number of breast cancer cells on the hybrid platform compared to untreated substrates. Whereas, fibroblast cells form stable adhesion with stretched and elongated cytoskeleton and actin filaments. The hybrid platforms perform as dual-acting cytophobic/cytostatic stages where Si nanostructures depress breast cancer cell adhesion while immobilized Au/Au-Pd nanoparticles are gradually released to affect any surviving cell on the nanostructures. The nanoparticles are believed to be taken up by breast cancer cells via endocytosis, which subsequently alter the cell nucleus and may cause cell death. The findings suggest that the density of nanostructures and concentration of coated nanoparticles play critical roles on cytophobic/cytostatic properties of the platforms on human breast cancer cells while having no or even cytophilic effects on fibroblast cells. Because of the remarkable contrary responses of normal and cancer cells to the proposed platform, we envision that it will provide novel applications in cancer research.

Regulation of Macrophage Recognition through the Interplay of Nanoparticle Surface Functionality and Protein Corona

Using a family of cationic gold nanoparticles (NPs) with similar size and charge, we demonstrate that proper surface engineering can control the nature and identity of protein corona in physiological serum conditions. The protein coronas were highly dependent on the hydrophobicity and arrangement of chemical motifs on NP surface. The NPs were uptaken in macrophages in a corona-dependent manner, predominantly through recognition of specific complement proteins in the NP corona. Taken together, this study shows that surface functionality can be used to tune the protein corona formed on NP surface, dictating the interaction of NPs with macrophages.

Application of Direct Current Atmospheric Pressure Glow Microdischarge Generated in Contact with a Flowing Liquid Solution for Synthesis of Au-Ag Core-Shell Nanoparticles

A direct current atmospheric pressure glow microdischarge (dc-μAPGD) generated between an Ar nozzle microjet and a flowing liquid was applied to produce Au-Ag core-shell nanoparticles (Au@AgCSNPs) in a continuous flow system. Firstly, operating dc-μAPGD with the flowing solution of the Au(III) ions as the cathode, the Au nanoparticles (AuNPs) core was produced. Next, to produce the core-shell nanostructures, the collected AuNPs solution was immediately mixed with an AgNO₃ solution and passed through the system with the reversed polarity to fabricate the Ag nanoshell on the AuNPs core. The formation of Au@AgCSNPs was confirmed using ultraviolet-visible (UV-Vis) absorbance spectrophotometry, transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS). Three localized surface plasmon resonance absorption bands with wavelengths centered at 372, 546, and 675 nm were observed in the UV-Vis spectrum of Au@AgCSNPs, confirming the reduction of both the Au(III) and Ag(I) ions. The right configuration of metals in Au@AgCSNPs was evidenced by TEM. The Au core diameter was 10.2 ± 2.0 nm, while the thickness of the Ag nanoshell was 5.8 ± 1.8 nm. The elemental composition of the bimetallic nanoparticles was also confirmed by EDS. It is possible to obtain 90 mL of a solution containing Au@AgCSNPs per hour using the applied microdischarge system.

Using the Power of Organic Synthesis for Engineering the Interactions of Nanoparticles with Biological Systems

The surface properties of nanoparticles (NPs) dictate their interaction with the outside world. The use of precisely designed molecular ligands to control NP surface properties provides an important toolkit for modulating their interaction with biological systems, facilitating their use in biomedicine. In this review we will discuss the application of the atom-by-atom control provided by organic synthesis to the generation of engineered nanoparticles, with emphasis on how the functionalization of NPs with these "small" organic molecules (Mw < 1,000) can be used to engineer NPs for a wide range of applications.

Construction of novel pH-sensitive hybrid micelles for enhanced extracellular stability and rapid intracellular drug release

Novel pH-sensitive hybrid micelles with high entrapment efficiency were constructed to realize rapid intracellular drug release without premature release.

The Interplay of Size and Surface Functionality on the Cellular Uptake of Sub-10 nm Gold Nanoparticles

Correlation of the surface physicochemical properties of nanoparticles with their interactions with biosystems provides key foundational data for nanomedicine. We report here the systematic synthesis of 2, 4, and 6 nm core gold nanoparticles (AuNP) featuring neutral (zwitterionic), anionic, and cationic headgroups. The cellular internalization of these AuNPs was quantified, providing a parametric evaluation of charge and size effects. Contrasting behavior was observed with these systems: with zwitterionic and anionic particles, uptake decreased with increasing AuNP size, whereas with cationic particles, uptake increased with increasing particle size. Through mechanistic studies of the uptake process, we can attribute these opposing trends to a surface-dictated shift in uptake pathways. Zwitterionic NPs are primarily internalized through passive diffusion, while the internalization of cationic and anionic NPs is dominated by multiple endocytic pathways. Our study demonstrates that size and surface charge interact in an interrelated fashion to modulate nanoparticle uptake into cells, providing an engineering tool for designing nanomaterials for specific biological applications.

The influence of stabilizers on the production of gold nanoparticles by direct current atmospheric pressure glow microdischarge generated in contact with liquid flowing cathode

Gold nanoparticles (Au NPs) were prepared by direct current atmospheric pressure glow microdischarge (dc-μAPGD) generated between a miniature argon flow microjet and a flowing liquid cathode. The applied discharge system was operated in a continuous flow liquid mode. The influence of various stabilizers added to the solution of the liquid cathode, i.e., gelatin (GEL), polyvinylpyrrolidone (PVP), or polyvinyl alcohol (PVA), as well as the concentration of the Au precursor (chloroauric acid, HAuCl₄) in the solution on the production growth of Au NPs was investigated. Changes in the intensity of the localized surface plasmon resonance (LSPR) band in UV/Vis absorption spectra of solutions treated by dc-μAPGD and their color were observed. The position and the intensity of the LSPR band indicated that relatively small nanoparticles were formed in solutions containing GEL as a capping agent. In these conditions, the maximum of the absorption LSPR band was at 531, 534, and 535 nm, respectively, for 50, 100, and 200 mg L^-1 of Au. Additionally, scanning electron microscopy (SEM) and dynamic light scattering (DLS) were used to analyze the structure and the morphology of obtained Au NPs. The shape of Au NPs was spherical and uniform. Their mean size was ca. 27, 73, and 92 nm, while the polydispersity index was 0.296, 0.348, and 0.456 for Au present in the solution of the flowing liquid cathode at a concentration of 50, 100, and 200 mg L^-1, respectively. The production rate of synthesized Au NPs depended on the precursor concentration with mean values of 2.9, 3.5, and 5.7 mg h^-1, respectively.

Inorganic nanoparticles engineered to attack bacteria

Antibiotics delivered to bacteria using engineered nanoparticles (NP), offer a powerful and efficient means to kill or control bacteria, especially those already resistant to antibiotics.

The impact of aminated surface ligands and silica shells on the stability, uptake, and toxicity of engineered silver nanoparticles

Inherent nanomaterial characteristics, composition, surface chemistry, and primary particle size, are known to impact particle stability, uptake, and toxicity. Nanocomposites challenge our ability to predict nanoparticle reactivity in biological systems if they are composed of materials with contrasting relative toxicities. We hypothesized that toxicity would be dominated by the nanoparticle surface (shell vs core), and that modulating the surface ligands would have a direct impact on uptake. We exposed developing zebrafish (Danio rerio) to a series of ~70 nm amine-terminated silver nanoparticles with silica shells (AgSi NPs) to investigate the relative influence of surface amination, composition, and size on toxicity. Like-sized aminated AgSi and Si NPs were more toxic than paired hydroxyl-terminated nanoparticles; however, both AgSi NPs were more toxic than the Si NPs, indicating a significant contribution of the silver core to the toxicity. Incremental increases in surface amination did not linearly increase uptake and toxicity, but did have a marked impact on dispersion stability. Mass-based exposure metrics initially supported the hypothesis that smaller nanoparticles (20 nm) would be more toxic than larger particles (70 nm). However, surface area-based metrics revealed that toxicity was independent of size. Our studies suggest that nanoparticle surfaces play a critical role in the uptake and toxicity of AgSi NPs, while the impact of size may be a function of the exposure metric used. Overall, uptake and toxicity can be dramatically altered by small changes in surface functionalization or exposure media. Only after understanding the magnitude of these changes, can we begin to understand the biologically available dose following nanoparticle exposure.

Control of nanoparticle penetration into biofilms through surface design

Quantum dots were used as fluorescent probes to investigate nanoparticle penetration into biofilms. The particle penetration behavior was found to be controlled by surface chemical properties.

Probing the Protein-Nanoparticle Interface: The Role of Aromatic Substitution Pattern on Affinity

A new class of cationic gold nanoparticles has been synthesized bearing benzyl moieties featuring -NO₂ and -OMe groups to investigate the regioisomeric control of aromatic nanoparticle-protein recognition. In general, nanoparticles bearing electron withdrawing group demonstrated higher binding affinities towards green fluorescent protein (GFP) compared to electron-donating groups. Significantly, a ~7.5 and ~4.3 fold increase in binding with GFP was observed for -NO2 groups in meta- and para-position respectively, while ortho-substitution showed similar binding compared to the unsubstituted ring. These findings demonstrated that nanoparticle-protein interaction can be controlled by the tuning the spatial orientation and the relative electronic properties of the aromatic substituents. This improved biomolecular recognition provides opportunities for enhanced biosensing and functional protein delivery to the cells.

25th anniversary article: interfacing nanoparticles and biology: new strategies for biomedicine

The exterior surface of nanoparticles (NPs) dictates the behavior of these systems with the outside world. Understanding the interactions of the NP surface functionality with biosystems enables the design and fabrication of effective platforms for therapeutics, diagnostics, and imaging agents. In this review, we highlight the role of chemistry in the engineering of nanomaterials, focusing on the fundamental role played by surface chemistry in controlling the interaction of NPs with proteins and cells.

Protein coronas suppress the hemolytic activity of hydrophilic and hydrophobic nanoparticles

The role of nanoparticle surface hydrophobicity on its hemolytic property is established in the absence and the presence of plasma proteins. Significantly, the formation of plasma protein corona on NP surface protects red blood cells from both hydrophilic and hydrophobic NP-mediated hemolysis.

Size dependent biological profiles of PEGylated gold nanorods

The interactions with proteins, cytotoxicity and blood compatibility of PEGylated gold nanorods are reviewed as a function of particle size.

High coating of Ru(II) complexes on gold nanoparticles for single particle luminescence imaging in cells

Gold nanoparticles are efficiently labelled with a luminescent ruthenium complex, producing 13 and 100 nm diameter, monodisperse red-emissive imaging probes with luminescence lifetimes prolonged over the molecular unit. Single, 100 nm particles are observed in whole cell luminescence imaging which reveals their biomolecular association with chromatin in the nucleus of cancer cells.

Influence of dispersion forces and ordering on the compositions of mixed monolayers of alkanoic acids on nanocrystalline TiO2 films

Lateral dispersion forces induce the ordering of n-alkanoic acids on nanocrystalline TiO2 films and cause the compositions of mixed monolayers to change. The equilibrium formation of single-component monolayers of n-alkanoic acids and 6-bromohexanoic acid (Br6A) on TiO2 was well-modeled by the Langmuir adsorption isotherm. Surface adduct formation constants were 10(3)-10(4) M(-1), and saturation amounts of adsorbates per projected surface area of TiO2 were on the order of 10(-7) mol cm(-2). The adsorption of n-heneicosanoic acid (21A) followed Langmuir kinetics, whereas the net rates of adsorption of shorter n-alkanoic acids and Br6A were slower than predicted by simple Langmuir kinetics, suggesting that desorption was non-negligible. At high surface coverages, n-alkanoic acids with 14 or more methylene groups formed ordered, crystalline monolayers, as evidenced by shifts of asymmetric and symmetric CH2 stretching bands in IR spectra. The extent of ordering was similar to that of self-assembled monolayers of alkanethiols on gold. The formation of ordered monolayers was well-modeled by an idealized mechanism, in which adsorption and desorption followed Langmuir kinetics and ordering was first-order with respect to the fractional surface coverage of adsorbates. Dispersion forces and ordering affected the compositions of mixed monolayers of 21A and Br6A on TiO2 films that remained in contact with mixed coadsorption solutions. When the fractional surface coverage of 21A was sufficiently high to induce ordering, it displaced Br6A from TiO2. We propose that these compositional changes were driven by the stabilization of 21A via cohesive lateral dispersion forces. Our results reveal that mixed monolayers on nanocrystalline TiO2 films are dynamic and that noncovalent intermolecular interactions can profoundly influence their compositions and properties.

Maltoheptaose promotes nanoparticle internalization by Escherichia coli

Nanoparticles conjugated with d-maltoheptaose (G7) showed a striking increase in the internalization by Escherichia coli. This applies to strains with and without the maltodextrin transport channel and particles ranging from a few to a hundred nanometers.

Surface decorated gold nanoparticles by linear and cyclic peptides as molecular transporters

Gold nanoparticles (AuNPs) were synthesized in situ in a green and rapid method from the reaction of reducing linear and cyclic peptides containing tryptophan and lysine residues, (KW)5 and cyclic [KW]5, with an aqueous solution of HAuCl4 and were evaluated as cellular nanodrug delivery systems. The cyclic or linear nature of the peptide was found to determine the morphology and size of the formed peptide-AuNPs and their in vitro molecular transporting efficiency. While cyclic [KW]5-AuNPs formed sponge-like agglomerates, linear (KW)5-AuNPs demonstrated ball-shaped structures. A comparative flow cytometry study showed that the cellular uptake of fluorescence-labeled anti-HIV drugs (emtricitabine (FTC) and lamivudine (3TC)) in human leukemia (CCRF-CEM) cells, and a negatively charged cell-impermeable phosphopeptide (GpYEEI) in human ovarian adecarcinoma (SK-OV-3) cells was significantly higher in the presence of cyclic [KW]5-AuNPs than that of linear (KW)5-AuNPs, parent cyclic [KW]5, and linear (KW)5 peptides. For example, the cellular uptake of F'-GpYEEI was enhanced 12.8-fold by c[KW]5-AuNPs. Confocal microscopy revealed the localization of fluorescence-labeled-3TC in the presence of c[KW]5-AuNPs mostly in nucleus in SK-OV-3 cells after 1 h. On the other hand, l(KW)5-AuNPs delivered fluorescence-labeled-3TC in cytoplasm. These data suggest that noncell penetrating peptides can be converted to efficient molecular transporters through peptide-capped AuNPs formation.

Co-delivery of a hydrophobic small molecule and a hydrophilic peptide by porous silicon nanoparticles

Nanoparticulate drug delivery systems offer remarkable opportunities for clinical treatment. However, there are several challenges when they are employed to deliver multiple cargos/payloads, particularly concerning the synchronous delivery of small molecular weight drugs and relatively larger peptides. Since porous silicon (PSi) nanoparticles (NPs) can easily contain high payloads of drugs with various properties, we evaluated their carrier potential in multi-drug delivery for co-loading of the hydrophobic drug indomethacin and the hydrophilic human peptide YY3-36 (PYY3-36). Sequential loading of these two drugs into the PSi NPs enhanced the drug release rate of each drug and also their amount permeated across Caco-2 and Caco-2/HT29 cell monolayers. Regardless of the loading approach used, dual or single, the drug permeation profiles were in good correlation with their drug release behaviour. Furthermore, the permeation studies indicated the critical role of the mucus intestinal layer and the paracellular resistance in the permeation of the therapeutic compounds across the intestinal wall. Loading with PYY3-36 also greatly improved the cytocompatibility of the PSi NPs. Conformational analysis indicated that the PYY3-36 could still display biological activity after release from the PSi NPs and permeation across the intestinal cell monolayers. These results are the first demonstration of the promising potential of PSi NPs for simultaneous multi-drug delivery of both hydrophobic and hydrophilic compounds.

The Gold Nanorod-Biology Interface: From Proteins to Cells to Tissue

Gold nanorods absorb and scatter light strongly in the near-infrared portion of the electromagnetic spectrum, making them ideal tissue contrast agents for imaging techniques such as optical coherence tomography (OCT). Strong interactions occur at the nano-bio interface, such as proteins binding to gold nanorods forming a 'corona.' To fulfill the promise of nanorods for applications such as contrast agents, we must better understand the intrinsic interactions of these nanomaterials with biological systems at the molecular, cellular and tissue level. In this paper, we briefly review the nanorod-protein interface. We then present some new fast relaxation imaging (FReI) measurements of how the presence of strongly-absorbing gold nanorods affects protein binding and folding, taking into account inner filter effects and the strong quenching effect of nanorods on fluorescent-labeled proteins. Next we show that two-photon photoluminescence of the gold nanorods can be used to image the nanorods in tissue constructs, allowing us to independently study their tissue distribution so they can be used successfully as contrast agents in optical coherence microscopy.

The role of surface functionality in determining nanoparticle cytotoxicity

Surface properties dictate the behavior of nanomaterials in vitro, in vivo, and in the environment. Such properties include surface charge and hydrophobicity. Also key are more complex supramolecular interactions such as aromatic stacking and hydrogen bonding, and even surface topology from the structural to the atomic level. Surface functionalization of nanoparticles (NPs) provides an effective way to control the interface between nanomaterials and the biological systems they are designed to interact with. In medicine, for instance, proper control of surface properties can maximize therapeutic or imaging efficacy while minimizing unfavorable side effects. Meanwhile, in environmental science, thoughtful choice of particle coating can minimize the impact of manufactured nanomaterials on the environment. A thorough knowledge of how NP surfaces with various properties affect biological systems is essential for creating NPs with such useful therapeutic and imaging properties as low toxicity, stability, biocompatibility, favorable distribution throughout cells or tissues, and favorable pharmacokinetic profiles--and for reducing the potential environmental impact of manufactured nanomaterials, which are becoming increasingly prominent in the marketplace. In this Account, we discuss our research and that of others into how NP surface properties control interactions with biomolecules and cells at many scales, including the role the particle surface plays in determining in vivo behavior of nanomaterials. These interactions can be benign, beneficial, or lead to dysfunction in proteins, genes and cells, resulting in cytotoxic and genotoxic responses. Understanding these interactions and their consequences helps us to design minimally invasive imaging and delivery agents. We also highlight in this Account how we have fabricated nanoparticles to act as therapeutic agents via tailored interactions with biomacromolecules. These particles offer new therapeutic directions from traditional small molecule therapies, and with potentially greater versatility than is possible with proteins and nucleic acids.

Inhibiting the growth of pancreatic adenocarcinoma in vitro and in vivo through targeted treatment with designer gold nanotherapeutics

Background

Pancreatic cancer is one of the deadliest of all human malignancies with limited options for therapy. Here, we report the development of an optimized targeted drug delivery system to inhibit advanced stage pancreatic tumor growth in an orthotopic mouse model.

Method/Principal Findings

Targeting specificity in vitro was confirmed by preincubation of the pancreatic cancer cells with C225 as well as Nitrobenzylthioinosine (NBMPR - nucleoside transporter (NT) inhibitor). Upon nanoconjugation functional activity of gemcitabine was retained as tested using a thymidine incorporation assay. Significant stability of the nanoconjugates was maintained, with only 12% release of gemcitabine over a 24-hour period in mouse plasma. Finally, an in vivo study demonstrated the inhibition of tumor growth through targeted delivery of a low dose of gemcitabine in an orthotopic model of pancreatic cancer, mimicking an advanced stage of the disease.

Conclusion

We demonstrated in this study that the gold nanoparticle-based therapeutic containing gemcitabine inhibited tumor growth in an advanced stage of the disease in an orthotopic model of pancreatic cancer. Future work would focus on understanding the pharmacokinetics and combining active targeting with passive targeting to further improve the therapeutic efficacy and increase survival.

Surface functionality of nanoparticles determines cellular uptake mechanisms in mammalian cells

Nanoparticles (NPs) are versatile scaffolds for numerous biomedical applications including drug delivery and bioimaging. The surface functionality of NPs essentially dictates intracellular NP uptake and controls their therapeutic action. Using several pharmacological inhibitors, it is demonstrated that the cellular uptake mechanisms of cationic gold NPs in both cancer (HeLa) and normal cells (MCF10A) strongly depend on the NP surface monolayer, and mostly involve caveolae and dynamin-dependent pathways as well as specific cell surface receptors (scavenger receptors). Moreover, these NPs show different uptake mechanisms in cancer and normal cells, providing an opportunity to develop NPs with improved selectivity for delivery applications.