Gold nanoparticle should understand protein corona for being a clinical nanomaterial

Preparation of sodium alginate and chitosan modified curcumin liposomes and study on the formation of protein corona

Curcumin (CUR) is a polyphenolic compound extracted from plants with a wide range of pharmacological activities. However, the low stability and bioavailability limits its practical application. This work utilized the chitosan (CH) and sodium alginate (SA) to modify the surface of the liposome to improve the stability of curcumin. Studies on the adsorption of pepsin to the surface of liposomes and the formation of protein coronas (PCs) were also carried out to investigate the in vivo behavior of the sodium alginate and chitosan modified curcumin liposomes (SA-CH-LPs). The result shown that the average particle size of SA-CH-LPs was around 220.7 ± 1.68 nm. X-ray Diffractometer (XRD) and differential scanning calorimeter (DSC) confirmed the successful preparation of SA-CH-LPs and illustrated their crystalline characteristics. The cytotoxicity of SA-CH-LPs was determined by CCK-8 assay and the results showed that the cell viability was above 80 % at different concentrations. In vitro results showed that the bioaccessibility of SA-CH-LPs (87.9 %) was better than curcumin liposomes (LPs) (66.4 %), and could better resist to catabolic degradation in the gastrointestinal environment. This work could provide the feasibility for improving the stability and bioaccessibility of the curcumin liposome, as well as given the preliminary evidence for investigation of the interaction with enzyme during the in vivo digestion process for the further application in food.

Characterization and Hemocompatibility of α, β, and γ Cyclodextrin-Modified Magnetic Nano-Adsorbents

Kidney dysfunction leads to the retention of metabolites within the blood that are not effectively cleared with conventional hemodialysis. Magnetic nanoparticle (MNP)-based absorbents have inherent properties that make them amenable to capturing toxins in the blood, notably a large surface area that can be chemically modified to enhance toxin capture and the ability to be easily collected from the blood using an external magnetic field. Cyclodextrins (CDs) present a chemical structure that facilitates the binding of small molecules. However, the hemocompatibility of MNPs modified with films composed of different native types of CDs (α, β, or γ) has not yet been investigated, which is information crucial to the potential clinical application of MNPs to supplement hemodialysis. To this end, films of α-, β-, or γ-CDs were formed on MNPs and characterized. The impact of these films on the adsorbed protein structure, composition of key adsorbed proteins, and clotting kinetics were evaluated. It was found that modified MNPs did not significantly affect the secondary structure of some proteins (albumin, lysozyme, α-lactalbumin). The adsorbed proteome from platelet-poor human plasma was evaluated as a function of film properties. Compared to non-modified nanoparticles, CD-modified MNPs exhibited a significant decrease in the adsorbed protein per surface area of MNPs. The immunoblot results showed variations in the adsorption levels of C3, fibrinogen, antithrombin, Factor XI, and plasminogen across CD-modified MNPs. The hemocompatibility experiments showed that CD-modified MNPs are compatible with human whole blood, with no significant impact on platelet activation, hemolysis, or hemostasis.

Complex Formation of Gold Nanoparticles with Collagen in Aqueous Media Studied by X-ray Scattering and Absorption Spectroscopy

Small-angle X-ray scattering and UV-vis absorption measurements were performed on mixed solutions of gold nanoparticles (AuNPs) and atelocollagen (AC), triple-helical collagen without telopeptide, in acetate buffer at pH 4 under different temperature conditions, i.e., preparation temperature Tprep and measurement temperature Tmeas. Due to the significantly higher electron density of gold than that of AC, the structure factor S(q) of AuNPs is readily estimated from the scattering intensities of AuNP-only and mixed solutions. The resulting S(q) profile for the mixed solution indicated significant attractive interactions, especially for the smaller AuNPs. Therefore, the sticky sphere model was applied to analyze S(q) to determine the interaction parameters at different Tprep and Tmeas. The attractive interactions between AuNPs were higher at higher Tprep, suggesting that single-chain AC tends to make the interactions between AuNPs more attractive than those for triple-helical AC. Complex formation was also detected by the aggregation-induced surface plasmon absorption shift. More densely packed AuNPs were detected from the absorption spectra for higher AuNP content at which the ζ potential disappeared, while a split absorption band was also found, indicating that not all AuNPs can form a complex with AC at ζ = 0.

Capped Plasmonic Gold and Silver Nanoparticles with Porphyrins for Potential Use as Anticancer Agents-A Review

Photothermal therapy (PTT) and photodynamic therapy (PDT) are potential cancer treatment methods that are minimally invasive with high specificity for malignant cells. Emerging research has concentrated on the application of metal nanoparticles encapsulated in porphyrin and their derivatives to improve the efficacy of these treatments. Gold and silver nanoparticles have distinct optical properties and biocompatibility, which makes them efficient materials for PDT and PTT. Conjugation of these nanoparticles with porphyrin derivatives increases their light absorption and singlet oxygen generation that create a synergistic effect that increases phototoxicity against cancer cells. Porphyrin encapsulation with gold or silver nanoparticles improves their solubility, stability, and targeted tumor delivery. This paper provides comprehensive review on the design, functionalization, and uses of plasmonic silver and gold nanoparticles in biomedicine and how they can be conjugated with porphyrins for synergistic therapeutic effects. Furthermore, it investigates this dual-modal therapy's potential advantages and disadvantages and offers perspectives for future prospects. The possibility of developing gold, silver, and porphyrin nanotechnology-enabled biomedicine for combination therapy is also examined.

Gold nanoparticles-mediated photothermal and photodynamic therapies for cancer

Cancer remains one of the major causes of death globally, with one out of every six deaths attributed to the disease. The impact of cancer is felt on psychological, physical, and financial levels, affecting individuals, communities, and healthcare institutions. Conventional cancer treatments have many challenges and inadequacies. Nanomedicine, however, presents a promising solution by not only overcoming these problems but also offering the advantage of combined therapy for treatment-resistant cancers. Nanoparticles specifically engineered for use in nanomedicine can be efficiently targeted to cancer cells through a combination of active and passive techniques, leading to superior tumor-specific accumulation, enhanced drug availability, and reduced systemic toxicity. Among various nanoparticle formulations designed for cancer treatment, gold nanoparticles have gained prominence in the field of nanomedicine due to their photothermal, photodynamic, and immunologic effects without the need for photosensitizers or immunotherapeutic agents. To date, there is no comprehensive literature review that focuses on the photothermal, photodynamic, and immunologic effects of gold nanoparticles. In this review, significant attention has been devoted to examining the parameters pertaining to the structure of gold nanoparticles and laser characteristics, which play a crucial role in influencing the efficacy of photothermal therapy (PTT) and photodynamic therapy (PDT). Moreover, this article provides insights into the success of PTT and PDT mediated by gold nanoparticles in primary cancer treatment, as well as the immunological effects of PTT and PDT on metastasis and recurrence, providing a promising strategy for cancer therapy. In summary, gold nanoparticles, with their unique properties, have the potential for clinical application in various cancer therapies, including the treatment of primary cancer, recurrence and metastasis.

Biomolecular Corona of Gold Nanoparticles: The Urgent Need for Strong Roots to Grow Strong Branches

Gold nanoparticles (GNPs) are largely employed in diagnostics/biosensors and are among the most investigated nanomaterials in biology/medicine. However, few GNP-based nanoformulations have received FDA approval to date, and promising in vitro studies have failed to translate to in vivo efficacy. One key factor is that biological fluids contain high concentrations of proteins, lipids, sugars, and metabolites, which can adsorb/interact with the GNP's surface, forming a layer called biomolecular corona (BMC). The BMC can mask prepared functionalities and target moieties, creating new surface chemistry and determining GNPs' biological fate. Here, the current knowledge is summarized on GNP-BMCs, analyzing the factors driving these interactions and the biological consequences. A partial fingerprint of GNP-BMC analyzing common patterns of composition in the literature is extrapolated. However, a red flag is also risen concerning the current lack of data availability and regulated form of knowledge on BMC. Nanomedicine is still in its infancy, and relying on recently developed analytical and informatic tools offers an unprecedented opportunity to make a leap forward. However, a restart through robust shared protocols and data sharing is necessary to obtain "stronger roots". This will create a path to exploiting BMC for human benefit, promoting the clinical translation of biomedical nanotools.

Redox-Responsive Gold Nanoparticles Coated with Hyaluronic Acid and Folic Acid for Application in Targeting Anticancer Therapy

Methotrexate (MTX) has poor water solubility and low bioavailability, and cancer cells can become resistant to it, which limits its safe delivery to tumor sites and reduces its clinical efficacy. Herein, we developed novel redox-responsive hybrid nanoparticles (NPs) from hyaluronic acid (HA) and 3-mercaptopropionic acid (MPA)-coated gold NPs (gold@MPA NPs), which were further conjugated with folic acid (FA). The design of FA-HA-ss-gold NPs aimed at enhancing cellular uptake specifically in cancer cells using an active FA/HA dual targeting strategy for enhanced tumor eradication. MTX was successfully encapsulated into FA-HA-ss-gold NPs, with drug encapsulation efficiency (EE) as high as >98.7%. The physicochemical properties of the NPs were investigated in terms of size, surface charges, wavelength reflectance, and chemical bonds. MTX was released in a sustained manner in glutathione (GSH). The cellular uptake experiments showed effective uptake of FA-HA-ss-gold over HA-ss-gold NPs in the deep tumor. Moreover, the release studies provided strong evidence that FA-HA-ss-gold NPs serve as GSH-responsive carriers. In vitro, anti-tumor activity tests showed that FA-HA-ss-gold/MTX NPs exhibited significantly higher cytotoxic activity against both human cervical cancer (HeLa) cells and breast cancer (BT-20) cells compared to gold only and HA-ss-gold/MTX NPs while being safe for human embryonic kidney (HEK-293) cells. Therefore, this present study suggests that FA-HA-ss-gold NPs are promising active targeting hybrid nanocarriers that are stable, controllable, biocompatible, biodegradable, and with enhanced cancer cell targetability for the safe delivery of hydrophobic anticancer drugs.

A novel microfluidic chip integrating with microcolumn array electrodes for rapid and ultrasensitive detection of alpha-fetoprotein

BACKGROUND

Cancer posed a serious threat to human health, and early diagnosis of cancer biomarker was extremely important for the treatment and control of cancer. Electrochemistry-based assays were low-cost, responsive and easy to operate, but there were some challenges in terms of accuracy, detection limit, efficiency and portability. The combination of microfluidic devices and electrochemical methods was expected to construct a high-performance sensing platform, but long-time antigen-antibody incubation was still required. Therefore, a novel microfluidic chip needs to be developed, which has the advantages of good portability, short incubation time, high accuracy, low detection limit and great application to point-of-care testing.

RESULTS

A microfluidic sensor based on microcolumn array electrodes was developed, in which microcolumns could create local mixed flow to reduce the incubation time of target molecules and enhance their interaction with the sensing interface. Besides, three dimensional Mxene fibers-gold nanoparticles (3D MF-Au) was modified on the microcolumn array electrodes to increase active sites and provide more electrolyte shuttle holes. The electrolyte turbulence caused by the microcolumn array electrodes could heighten the contact between the target molecules and sensing interface and accelerate the transfer of redox pairs, thus reducing the incubation time of the target molecules and improving the electrochemical responses in synergy with the 3D MF-Au. Herein, the detection of AFP was chosen as a model, and the microfluidic sensor possessed superior performance for analysis of AFP in the range of 0.1 pg mL-1 - 200 ng mL-1 with a low detection limit (LOD) of 0.0648 pg mL-1.

SIGNIFICANCE

This microfluidic chip integrating with microcolumn array electrodes has been successfully implemented to detect AFP in human serum, and the results were consistent with that of electrochemical chemiluminescence method. The microfluidic chip provided a new strategy of portability, shortening incubation time and enhancing electrical signals for antigen detection of real samples, which showed great utilization potentiality in point-of-care testing.

Role of Surface Curvature in Gold Nanostar Properties and Applications

Gold nanostars (AuNSs) are nanoparticles with intricate three-dimensional structures and shape-dependent optoelectronic properties. For example, AuNSs uniquely display three distinct surface curvatures, i.e. neutral, positive, and negative, which provide different environments to adsorbed ligands. Hence, these curvatures are used to introduce different surface chemistries in nanoparticles. This review summarizes and discusses the role of surface curvature in AuNS properties and its impact on biomedical and chemical applications, including surface-enhanced Raman spectroscopy, contrast agent performance, and catalysis. We examine the main synthetic approaches to generate AuNSs, control their morphology, and discuss their benefits and drawbacks. We also describe the optical characteristics of AuNSs and discuss how these depend on nanoparticle morphology. Finally, we analyze how AuNS surface curvature endows them with properties distinctly different from those of other nanoparticles, such as strong electromagnetic fields at the tips and increased hydrophilic environments at the indentations, together making AuNSs uniquely useful for biosensing, imaging, and local chemical manipulation.

Protein corona, influence on drug delivery system and its improvement strategy: A review

Nano drug delivery systems offer several benefits, including enhancing drug solubility, regulating drug release, prolonging drug circulation time, and minimized toxicity and side effects. However, upon entering the bloodstream, nanoparticles (NPs) encounter a complex biological environment and get absorbed by various biological components, primarily proteins, leading to the formation of a 'Protein Corona'. The formation of the protein corona is affected by the characteristics of NPs, the physiological environment, and experimental design, which in turn affects of the immunotoxicity, specific recognition, cell uptake, and drug release of NPs. To improve the abundance of a specific protein on NPs, researchers have explored pre-coating, modifying, or wrapping NPs with the cell membrane to reduce protein adsorption. This paper, we have reviewed studies of the protein corona in recent years, summarized the formation and detection methods of the protein corona, the effect of the protein corona composition on the fate of NPs, and the design of new drug delivery systems based on the optimization of protein corona to provide a reference for further study of the protein corona and a theoretical basis for the clinical transformation of NPs.

Design of flavonol-loaded cationic gold nanoparticles with enhanced antioxidant and antibacterial activities and their interaction with proteins

In this work, four structurally similar flavonols (galangin, kaempferol, quercetin and myricetin) were coated on the surface of (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide (MUTAB)‑gold nanoparticles (AuNPs) by two-step phase transfer and self-assembly, and the cationic MUTAB- AuNPs coated with flavonols (flavonol-MUTAB-AuNPs) were designed. Free radical scavenging and antibacterial experiments show that flavonol-MUTAB-AuNPs greatly improve the scavenging effect on DPPH, hydroxyl and superoxide anion radicals, and significantly enhance the inhibition effect on Staphylococcus aureus and Escherichia coli compared with flavonols and AuNPs. Then γ-globulin, fibrinogen, trypsin and pepsin were selected as representative proteins and their interaction with flavonol-MUTAB-AuNPs were investigated by various spectroscopic techniques. The fluorescence quenching mechanism of these four proteins by flavonol-MUTAB-AuNPs is static quenching. The binding constants Ka between them are in the range of 103 to 106. The interaction between them is endothermic, entropy-driven spontaneous process, and the main non-covalent force is the hydrophobic interaction. The effect of flavonol-MUTAB-AuNPs on the structure of the four proteins were investigated using UV-vis absorption spectra, synchronous fluorescence spectra and circular dichroism spectra. These results offer important insights into the essence of the interaction between flavonol-MUTAB-AuNPs and γ-globulin/fibrinogen/trypsin/pepsin. They will contribute to the development of safe and effective flavonol-MUTAB-AuNPs in biomedical fields.

A Protease-Responsive Polymer/Peptide Conjugate and Reversible Assembly of Silver Clusters for the Detection of Porphyromonas gingivalis Enzymatic Activity

We report the reversible aggregation of silver nanoparticle (AgNP) assemblies using the combination of a cationic arginine-based peptide and sulfur-capped polyethylene glycol (PEG). The formation and dissociation of the aggregates were studied by optical methods and electron microscopy. The dissociation of silver clusters depends on the peptide sequence and PEG size. A molecular weight of 1 kDa for PEG was optimal for the dissociation. The most important feature of this dissociation method is that it can operate in complex biofluids such as plasma, saliva, bile, urine, cell media, or even seawater without a significant decrease in performance. Moreover, the peptide-particle assemblies are highly stable and do not degrade (or express of loss of signal upon dissociation) when dried and resolubilized, frozen and thawed, or left in daylight for a month. Importantly, the dissociation capacity of PEG can be reduced via the conjugation of a peptide-cleavable substrate. The dissociation capacity is restored in the presence of an enzyme. Based on these findings, we designed a PEG-peptide hybrid molecule specific to the Porphyromonas gingivalis protease RgpB. Our motivation was that this bacterium is a key pathogen in periodontitis, and RgpB activity has been correlated with chronic diseases including Alzheimer's disease. The RgpB limit of detection was 100 pM RgpB in vitro. This system was used to measure RgpB in gingival crevicular fluid (GCF) samples with a detection rate of 40% with 0% false negatives versus PCR for P. gingivalis (n = 37). The combination of PEG-peptide and nanoparticles dissociation method allows the development of convenient protease sensing that can operate independently of the media composition.

The role of protein corona on nanodrugs for organ-targeting and its prospects of application

Nowadays, nanodrugs become a hotspot in the high-end medical field. They have the ability to deliver drugs to reach their destination more effectively due to their unique properties and flexible functionalization. However, the fate of nanodrugs in vivo is not the same as those presented in vitro, which indeed influenced their therapeutic efficacy in vivo. When entering the biological organism, nanodrugs will first come into contact with biological fluids and then be covered by some biomacromolecules, especially proteins. The proteins adsorbed on the surface of nanodrugs are known as protein corona (PC), which causes the loss of prospective organ-targeting abilities. Fortunately, the reasonable utilization of PC may determine the organ-targeting efficiency of systemically administered nanodrugs based on the diverse expression of receptors on cells in different organs. In addition, the nanodrugs for local administration targeting diverse lesion sites will also form unique PC, which plays an important role in the therapeutic effect of nanodrugs. This article introduced the formation of PC on the surface of nanodrugs and summarized the recent studies about the roles of diversified proteins adsorbed on nanodrugs and relevant protein for organ-targeting receptor through different administration pathways, which may deepen our understanding of the role that PC played on organ-targeting and improve the therapeutic efficacy of nanodrugs to promote their clinical translation.

Hemocompatibility of β-Cyclodextrin-Modified (Methacryloyloxy)ethyl Phosphorylcholine Coated Magnetic Nanoparticles

Adsorbing toxins from the blood to augment membrane-based hemodialysis is an active area of research. Films composed of β-cyclodextrin-co-(methacryloyloxy)ethyl phosphorylcholine (p(PMβCD-co-MPC)) with various monomer ratios were formed on magnetic nanoparticles and characterized. Surface chemistry effects on protein denaturation were evaluated and indicated that unmodified magnetic nanoparticles greatly perturbed the structure of proteins compared to coated particles. Plasma clotting assays were conducted to investigate the stability of plasma in the presence of particles, where a 2:2 monomer ratio yielded the best results for a given total surface area of particles. Total protein adsorption results revealed that modified surfaces exhibited reduced protein adsorption compared to bare particles, and pure MPC showed the lowest adsorption. Immunoblot results showed that fibrinogen, α1-antitrypsin, vitronectin, prekallikrein, antithrombin, albumin, and C3 correlated with film composition. Hemocompatibility testing with whole blood illustrated that the 1:3 ratio of CD to MPC had a negative impact on platelets, as evidenced by the increased activation, reduced response to an agonist, and reduced platelet count. Other formulations had statistically significant effects on platelet activation, but no formulation yielded apparent adverse effects on hemostasis. For the first time, p(PMβCD-co-MPC)-coated MNP were synthesized and their general hemocompatibility assessed.

Neural modulation with photothermally active nanomaterials

Modulating neural electrophysiology with high precision is essential for understanding neural communication and for the diagnosis and treatment of neural disorders. Photothermal modulation offers a remote and non-genetic method for neural modulation with high spatiotemporal resolution and specificity. This technique induces highly localized and transient temperature changes at the cell membrane interfaced with photothermally active nanomaterials. This rapid temperature change affects the electrical properties of the cell membrane or temperature-sensitive ion channels. In this Review, we discuss the fundamental material properties and illumination conditions that are necessary for nanomaterial-assisted photothermal neural excitation and inhibition. We examine how this versatile technique allows direct investigation of neural electrophysiology and signalling pathways in two-dimensional and three-dimensional cell cultures and tissues, and highlight the scientific and technological challenges in terms of cellular specificity, light delivery and biointerface stability on the road to clinical translation.

Artificial intelligence aids in development of nanomedicines for cancer management

Over the last decade, the nanomedicine has experienced unprecedented development in diagnosis and management of diseases. A number of nanomedicines have been approved in clinical use, which has demonstrated the potential value of clinical transition of nanotechnology-modified medicines from bench to bedside. The application of artificial intelligence (AI) in development of nanotechnology-based products could transform the healthcare sector by realizing acquisition and analysis of large datasets, and tailoring precision nanomedicines for cancer management. AI-enabled nanotechnology could improve the accuracy of molecular profiling and early diagnosis of patients, and optimize the design pipeline of nanomedicines by tuning the properties of nanomedicines, achieving effective drug synergy, and decreasing the nanotoxicity, thereby, enhancing the targetability, personalized dosing and treatment potency of nanomedicines. Herein, the advances in AI-enabled nanomedicines in cancer management are elaborated and their application in diagnosis, monitoring and therapy as well in precision medicine development is discussed.

Advanced Drug Delivery Systems for Renal Disorders

Kidney disease management and treatment are currently causing a substantial global burden. The kidneys are the most important organs in the human urinary system, selectively filtering blood and metabolic waste into urine via the renal glomerulus. Based on charge and/or molecule size, the glomerular filtration apparatus acts as a barrier to therapeutic substances. Therefore, drug distribution to the kidneys is challenging, resulting in therapy failure in a variety of renal illnesses. Hence, different approaches to improve drug delivery across the glomerulus filtration barrier are being investigated. Nanotechnology in medicine has the potential to have a significant impact on human health, from illness prevention to diagnosis and treatment. Nanomaterials with various physicochemical properties, including size, charge, surface and shape, with unique biological attributes, such as low cytotoxicity, high cellular internalization and controllable biodistribution and pharmacokinetics, have demonstrated promising potential in renal therapy. Different types of nanosystems have been employed to deliver drugs to the kidneys. This review highlights the features of the nanomaterials, including the nanoparticles and corresponding hydrogels, in overcoming various barriers of drug delivery to the kidneys. The most common delivery sites and strategies of kidney-targeted drug delivery systems are also discussed.

An Overview on Gold Nanorods as Versatile Nanoparticles in Cancer Therapy

Gold nanorods (GNRs/AuNRs) are a group of gold nanoparticles which their simple surface chemistry allows for various surface modifications, providing the possibility of using them in the fabrication of biocompatible and functional nano-agents for cancer therapy. AuNRs, moreover, exhibit a maximum absorption of longitudinal localized surface plasmon resonance (LSPR) in the near-infrared (NIR) region which overlaps with NIR bio-tissue 'window' suggesting that they are proper tools for thermal ablation of cancer cells. AuNRs can be used for induction of mono or combination therapies by administering various therapeutic approaches such as photothermal therapy (PTT), photodynamic therapy (PDT), chemotherapy (CT), radiotherapy (RT), and gene therapy (GT). In this review, anticancer therapeutic capacities of AuNRs along with different surface modifications are summarized comprehensively. The roles of AuNRs in fabrication of various nano-constructs are also discussed.

Current nanotechnological strategies using lipids, carbohydrates, proteins and metal conjugates-based carrier systems for diagnosis and treatment of tuberculosis - A review

Tuberculosis is a fatal disease caused by Mycobacterium tuberculosis with highest morbidity and mortality every year. The evolution of anti-TB drugs is promising in controlling and treating TB. Yet, the drug response varies depending on the bacterial load and host immunological profiles. The prolonged anti-TB treatment regimen and high pill burden leads to poor adherence to treatment and acquired drug resistance. In the clinical arena, sustainable nanotechnology improves the targeted strategies leading to enhance therapeutic recovery with minimum treatment duration and virtuous drug adherence. Determinants of nanosystems are the size, nature, formulation techniques, stable dosing patterns, bioavailability and toxicity. In the treatment of chronic illness, nanomedicines inclusive of biological macromolecules such as lipids, peptides, and nucleic acids occur to be a successive alternative to synthetic carriers. Most biological nanomaterials possess antimicrobial properties with other intrinsic characteristics. Recently, the pulmonary delivery of anti-TB drugs through polymeric nanocarrier systems is shown to be effective in achieving optimal drug levels in lungs for longer duration, enhanced tissue permeation and sustained systemic clearance. This thematic review provides a holistic insight into the nanodelivery systems pertinent to the therapeutic applications in pulmonary tuberculosis describing the choice of carriers, optimized process, metabolic action and excretion processes.

Di-Arginine Additives for Dissociation of Gold Nanoparticle Aggregates: A Matrix-Insensitive Approach with Applications in Protease Detection

We report the reversible aggregation of gold nanoparticles (AuNPs) assemblies via a di-arginine peptide additive and thiolated PEGs (HS-PEGs). The AuNPs were first aggregated by attractive forces between the citrate-capped surface and the arginine side chains. We found that the HS-PEG thiol group has a higher affinity for the AuNP surface, thus leading to redispersion and colloidal stability. In turn, there was a robust and obvious color change due to on/off plasmonic coupling. The assemblies' dissociation was directly related to the HS-PEG structural properties such as their size or charge. As an example, HS-PEGs with a molecular weight below 1 kDa could dissociate 100% of the assemblies and restore the exact optical properties of the initial AuNP suspension (prior to the assembly). Surprisingly, the dissociation capacity of HS-PEGs was not affected by the composition of the operating medium and could be performed in complex matrices such as plasma, saliva, bile, urine, cell lysates, or even seawater. The high affinity of thiols for the gold surface encompasses by far the one of endogenous molecules and is thus favored. Moreover, starting with AuNPs already aggregated ensured the absence of a background signal as the dissociation of the assemblies was far from spontaneous. Remarkably, it was possible to dry the AuNP assemblies and solubilize them back with HS-PEGs, improving the colorimetric signal generation. We used this system for protease sensing in biological fluids. Trypsin was chosen as the model enzyme, and highly positively charged peptides were conjugated to HS-PEG molecules as cleavage substrates. The increase of positive charge of the HS-PEG-peptide conjugate quenched the dissociation capacity of the HS-PEG molecules, which could only be restored by the proteolytic cleavage. Picomolar limit of detection was obtained as well as the detection in saliva or urine.

The Surface Charge of Polymer-Coated Upconversion Nanoparticles Determines Protein Corona Properties and Cell Recognition in Serum Solutions

Applications of nanoparticles (NPs) in the life sciences require control over their properties in protein-rich biological fluids, as an NP quickly acquires a layer of proteins on the surface, forming the so-called "protein corona" (PC). Understanding the composition and kinetics of the PC at the molecular level is of considerable importance for controlling NP interaction with cells. Here, we present a systematic study of hard PC formation on the surface of upconversion nanoparticles (UCNPs) coated with positively-charged polyethyleneimine (PEI) and negatively-charged poly (acrylic acid) (PAA) polymers in serum-supplemented cell culture medium. The rationale behind the choice of UCNP is two-fold: UCNP represents a convenient model of NP with a size ranging from 5 nm to >200 nm, while the unique photoluminescent properties of UCNP enable direct observation of the PC formation, which may provide new insight into this complex process. The non-linear optical properties of UCNP were utilised for direct observation of PC formation by means of fluorescence correlation spectroscopy. Our findings indicated that the charge of the surface polymer coating was the key factor for the formation of PC on UCNPs, with an ensuing effect on the NP-cell interactions.

Targeting Ultrasmall Gold Nanoparticles with cRGD Peptide Increases the Uptake and Efficacy of Cytotoxic Payload

Cyclic arginyl-glycyl-aspartic acid peptide (cRGD) peptides show a high affinity towards αVβ3 integrin, a receptor overexpressed in many cancers. We aimed to combine the versatility of ultrasmall gold nanoparticles (usGNP) with the target selectivity of cRGD peptide for the directed delivery of a cytotoxic payload in a novel design. usGNPs were synthesized with a modified Brust-Schiffrin method and functionalized via amide coupling and ligand exchange and their uptake, intracellular trafficking, and toxicity were characterized. Our cRGD functionalized usGNPs demonstrated increased cellular uptake by αVβ3 integrin expressing cells, are internalized via clathrin-dependent endocytosis, accumulated in the lysosomes, and when loaded with mertansine led to increased cytotoxicity. Targeting via cRGD functionalization provides a mechanism to improve the efficacy, tolerability, and retention of therapeutic GNPs.

Quantitative comparison of the protein corona of nanoparticles with different matrices

Nanoparticles (NPs) are paving the way for improved treatments for difficult to treat diseases diseases; however, much is unknown about their fate in the body. One important factor is the interaction between NPs and blood proteins leading to the formation known as the “protein corona” (PC). The PC, consisting of the Hard (HC) and Soft Corona (SC), varies greatly based on the NP composition, size, and surface properties. This highlights the need for specific studies to differentiate the PC formation for each individual NP system. This work focused on comparing the HC and SC of three NPs with different matrix compositions: a) polymeric NPs based on poly(lactic-co-glycolic) acid (PLGA), b) hybrid NPs consisting of PLGA and Cholesterol, and c) lipidic NPs made only of Cholesterol. NPs were formulated and characterized for their physico-chemical characteristics and composition, and then were incubated in human plasma. In-depth purification, identification, and statistical analysis were then performed to identify the HC and SC components. Finally, similar investigations demonstrated whether the presence of a targeting ligand on the NP surface would affect the PC makeup. These results highlighted the different PC fingerprints of these NPs, which will be critical to better understand the biological influences of the PC and improve future NP designs.

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NPs with different matrices were formulated: PLGA, Cholesterol, or mixed PLGA-Chol hybrids.

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The hard and soft corona of each formulation was quantified and compared.

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The PC seems to be more strongly affected by the polymer rather than the lipid in mixed NPs.

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The soft corona depends more on the hard corona composition than on the matrix.

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Surface modification with a targeting ligand did not influence PC composition.

Two different protein corona formation modes on Soluplus® nanomicelles

Soluplus® nanomicelles have been widely reported in biomedical field for their excellent drug loading capacity and solubility enhancement ability. However, when administrated in vivo, the protein corona will be formed on Soluplus® nanomicelles, significantly affecting their drug delivery performance. Up to now, few studies examined the protein corona formation process and its impact factors of Soluplus® nanomicelles. The multiple proteins in biofluids may form protein corona in different modes due to their diversified properties. In this study, Bovine serum albumin (BSA), Lysozyme (Lyso) and Bovine hemoglobin (BHb) were chosen as model proteins to investigate the protein corona formation process of Soluplus® nanomicelles. By analyzing the polarity of the protein amino acid residues distributing microenvironments, the results showed that there were two different protein corona formation modes, i.e., surface adsorption and insertion, which were determined by the hydrophilicity of proteins. The hydrophobic BHb followed the insertion mode while hydrophilic BSA and Lyso followed the surface adsorption mode. Ultimately, upon protein corona formation, the size and surface chemistry of nanomicelles was significantly affected. We believe this study will provide a new research paradigm to the design and application of Soluplus® nanomicelles.

Gold Nanorods-Based Photothermal Therapy: Interactions Between Biostructure, Nanomaterial, and Near-Infrared Irradiation

Gold nanorods (AuNRs) are ideal inorganic nanophotothermal agents with unique characteristics, including local surface plasmon resonance effects, easy scale preparation and functional modification, and good biocompatibility. This review summarizes several recent advances in AuNRs-based photothermal therapy (PTT) research. Functionalized AuNRs photothermal agents have optimized biocompatibility and targeting properties. The multifunctional AuNRs nanoplatform composite structure meets the requirements for synergistic effects of PTT, photoacoustic imaging, and other therapeutic methods. Photothermal therapy with AuNRs (AuNRs-PTT) is widely used to treat tumors and inflammatory diseases; its tumor-targeting, tumor metastasis inhibition, and photothermal tumor ablation abilities have remarkable curative effects. An in-depth study of AuNRs in living systems and the interactions between biological structure, nanomaterial, and near-infrared irradiation could lay the foundation for further clinical research and the broad application of AuNRs in PTT.

Versatile Protein Coronation Approach with Multiple Depleted Serum for Creating Biocompatible, Precision Nanomedicine

The protein corona effect has long been treated as the evil source behind delivery efficacy issues. In this study, this concept is challenged by showcasing that the protein corona can serve as a versatile functionalization approach to improve the delivery efficacy or mitigate nanocytotoxicity. To this end, the depleted serum is introduced to create nanomaterials carrying functionally distinct protein corona, referred to as PCylated nanomaterials. It is confirmed that the passivation with depleted serum helps reduce the toxicity and pro-inflammatory response. Furthermore, the same method can be leveraged to enhance the capacity of nanomaterials to undergo endocytosis as well as their potential as an agonist for the NF-κB pathways. The comparable stability of protein corona created by late and early-stage serum reveals that the chanceless interaction with nanomaterials, rather than an inadequate binding strength, may be behind the failure of enriching certain components. The PCylation strategy is extended to cancer patient-derived fluid, creating a set of T1 and T3-stage cancer-specific nanotherapeutics to retard the metastasis of cancer cells, while leaving normal endothelial negligibly affected. It is hoped the novel PCylation approach validated here can shed light on the future development of precision nanomedicine with improved delivery efficacy.

Artificial engineering of the protein corona at bio-nano interfaces for improved cancer-targeted nanotherapy

Nanoparticles (NPs) have been demonstrated in numerous applications as anticancer, antibacterial and antioxidant agents. Artificial engineering of protein interactions with NPs in biological systems is crucial to develop potential NPs for drug delivery and cancer nanotherapy. The protein corona (PC) on the NP surface, displays an interface between biomacromolecules and NPs, governing their pharmacokinetics and pharmacodynamics. Upon interaction of proteins with the NP surface, their surface features are modified and they can easily be removed from the circulation by the mononuclear phagocytic system (MPS). PC properties heavily depend on the biological microenvironment and NP surface physicochemical parameters. Based on this context, we have surveyed different approaches that have been used for artificial engineering of the PC composition on NP surfaces. We discuss the effects of NP size, shape, surface modifications (PEGylation, self-peptide, other polymers), and protein pre-coating on the PC properties. Additionally, other factors including protein source and structure, intravenous injection and the subsequent shear flow, plasma protein gradients, temperature and local heat transfer, and washing media are considered in the context of their effects on the PC properties and overall target cellular effects. Moreover, the effects of NP-PC complexes on cancer cells based on cellular interactions, organization of intracellular PC (IPC), targeted drug delivery (TDD) and regulation of burst drug release profile of nanoplatforms, enhanced biocompatibility, and clinical applications were discussed followed by challenges and future perspective of the field. In conclusion, this paper can provide useful information to manipulate PC properties on the NP surface, thus trying to provide a literature survey to shorten their shipping from preclinical to clinical trials and to lay the basis for a personalized PC.

The interaction mechanism between gold nanoparticles and proteins: Lysozyme, trypsin, pepsin, γ-globulin, and hemoglobin

In this study, the interaction between gold nanoparticles (AuNPs) and proteins (including lysozyme, trypsin, pepsin, γ-globulin and hemoglobin) was investigated by UV-visible absorption spectroscopy, fluorescence spectroscopy, circular dichroism (CD) spectroscopy and protein activity assay. AuNPs was synthesized using reduction of HAuCl₄ with sodium citrate. The formation of AuNPs was confirmed from the characteristic surface plasmon resonance band at 521 nm and transmission electron microscopy revealed the average particle size was about 10 nm. The results reveal that AuNPs can interact with proteins to form a "protein corona (PC)", but the protein concentration required to form a relatively stable PC is not the same. The quenching mechanism of proteins by AuNPs is arisen from static quenching. The binding constants of AuNPs with proteins are in the range from 10⁶ to 10¹⁰ L mol^-1, and the order is pepsin > γ-globulin > hemoglobin > trypsin > lysozyme at 298 K. Van der Waals forces and hydrogen bonds are the main forces for the lysozyme-AuNPs system. The interaction between trypsin/pepsin/γ-globulin/hemoglobin and AuNPs is mainly by hydrophobic interaction. The addition of AuNPs has an effect on the secondary structure of proteins as confirmed from CD spectra. The change in secondary structure of different proteins is different and seems to have little relation with the binding constant. The activity of lysozyme/trypsin/pepsin decreases with the addition of AuNPs.

Reduced Genotoxicity of Gold Nanoparticles With Protein Corona in Allium cepa

Increased usage of gold nanoparticles (AuNPs) in biomedicine, biosensing, diagnostics and cosmetics has undoubtedly facilitated accidental and unintentional release of AuNPs into specific microenvironments. This is raising serious questions concerning adverse effects of AuNPs on off-target cells, tissues and/or organisms. Applications utilizing AuNPs will typically expose the nanoparticles to biological fluids such as cell serum and/or culture media, resulting in the formation of protein corona (PC) on the AuNPs. Evidence for PC altering the toxicological signatures of AuNPs is well studied in animal systems. In this report, we observed significant genotoxicity in Allium cepa root meristematic cells (an off-target bioindicator) treated with high concentrations (≥100 µg/ml) of green-synthesized vanillin capped gold nanoparticles (VAuNPs). In contrast, protein-coated VAuNPs (PC-VAuNPs) of similar concentrations had negligible genotoxic effects. This could be attributed to the change in physicochemical characteristics due to surface functionalization of proteins on VAuNPs and/or differential bioaccumulation of gold ions in root cells. High elemental gold accumulation was evident from µ-XRF mapping in VAuNPs-treated roots compared to treatment with PC-VAuNPs. These data infer that the toxicological signatures of AuNPs are influenced by the biological route that they follow to reach off-target organisms such as plants. Hence, the current findings highlight the genotoxic risk associated with AuNPs, which, due to the enhanced utility, are emerging as new pollutants. As conflicting observations on the toxicity of green-synthesized AuNPs are increasingly reported, we recommend that detailed studies are required to investigate the changes in the toxicological signatures of AuNPs, particularly before and after their interaction with biological media and systems.

Current progress in aptamer-based sensing tools for ultra-low level monitoring of Alzheimer's disease biomarkers

Alzheimer's disease (AD) as common late-life dementia is pathologically associated with the irreversible and progressive disorder, misfolding, deposition, and accumulation of the brain proteins. Especially, the formation of fibrous amyloid plaques by aggregation of amyloid-β peptides is the pathological cause of this neurologic disorder disease. Besides, tau protein isoforms destabilize the microtubule filaments through post-translational modifications and induce nerve cells' death. Amyloid-β peptides and tau proteins are considered as the critical symptom and reliable molecular biomarkers for the early diagnosis of AD. AD is characterized by impaired thinking proficiencies, cognitive decline, memory loss, and behavioral disability. Since there is no efficacious therapy for AD at present, the development of precise sensing tools for the early diagnosis of this disease is essential and crucial. Aptamer-based biosensors (aptasensors) have acquired utmost importance in the field of AD healthcare, due to excellent sensitivity and specificity, ease-of-use, cost-effectiveness, portability, and rapid assay time. Here, we highlight the recent developments and novel perspectives in the field of aptasensor design to quantitatively monitor the AD biomarkers. Finally, some results are represented to achieve a promising viewpoint for introducing the novel aptasensor test kits in the future.

Engineering surface patterns on nanoparticles: New insights on nano-bio interactions

The surface properties of nanoparticles affect their fates in biological systems. Based on nanotechnology and methodology, pioneering works have explored the effects of chemical surface patterns on the behavior of...

Bacteria and cells as alternative nano-carriers for biomedical applications

INTRODUCTION

Nano-based systems have received a lot of attention owing to their particular properties and, hence, have been proposed for a wide variety of biomedical applications. These nanosystems could be potentially employed for diagnosis and therapy of different medical issues. Although these nanomaterials are designed for specific tasks, interactions, and transformations when administered to the human body affect their performance and behavior. In this regard, bacteria and other cells have been presented as alternative nanocarriers. These microorganisms can be genetically modified and customized for a more specific therapeutic action and, in combination with nanomaterials, can lead to bio-hybrids with a unique potential for biomedical purposes.

AREAS COVERED

Literature regarding bacteria and cells employed in combination with nanomaterials for biomedical applications is revised and discussed in this review. The potential as well as the limitations of these novel bio-hybrid systems are evaluated. Several examples are presented to show the performance of these alternative nanocarriers.

EXPERT OPINION

Bio-hybrid systems have shown their potential as alternative nanocarriers as they contribute to better performance than traditional nano-based systems. Nevertheless, their limitations must be studied, and advantages and drawbacks assessed before their application to medicine.

Collagen – A Newly Discovered Major Player in Protein Corona Formation on Nanoparticles

Tracking protein corona (PC) formation on the surface of nanoparticles (NPs) is a prerequisite for successful design of next generation nanocarriers with predictable fate and behavior. However, PC formation has...

Stimuli-responsive nanomaterials for cancer treatment: boundaries, opportunities and applications

Small molecule drugs, including most chemotherapies, are rapidly degraded and/or eliminated from the body, which is why high doses of these drugs are necessary, potentially producing toxic effects. Several types of nanoparticles loaded with anti-cancer drugs have been designed to overcome the disadvantages of conventional therapies. Modified nanoparticles can circulate for a long time, thus improving the solubility and biodistribution of drugs. Furthermore, they also allow the controlled release of the payload once its target tissue has been reached. These mechanisms can reduce the exposure of healthy tissues to chemotherapeutics, since the drugs are only released in the presence of specific tumour stimuli. Overall, these properties can improve the effectiveness of treatments while reducing undesirable side effects. In this article, we review the recent advances in stimuli-responsive albumin, gold and magnetic nanostructures for controlled anti-cancer drug delivery. These nanostructures were designed to release drugs in response to different internal and external stimuli of the cellular environment, including pH, redox, light and magnetic fields. We also describe various examples of applications of these nanomaterials. Overall, we shed light on the properties, potential clinical translation and limitations of stimuli-responsive nanoparticles for cancer treatment.

Multifunctional Gold Nanoparticles for Improved Diagnostic and Therapeutic Applications: A Review

The medical properties of metals have been explored for centuries in traditional medicine for the treatment of infections and diseases and still practiced to date. Platinum-based drugs are the first class of metal-based drugs to be clinically used as anticancer agents following the approval of cisplatin by the United States Food and Drug Administration (FDA) over 40 years ago. Since then, more metals with health benefits have been approved for clinical trials. Interestingly, when these metals are reduced to metallic nanoparticles, they displayed unique and novel properties that were superior to their bulk counterparts. Gold nanoparticles (AuNPs) are among the FDA-approved metallic nanoparticles and have shown great promise in a variety of roles in medicine. They were used as drug delivery, photothermal (PT), contrast, therapeutic, radiosensitizing, and gene transfection agents. Their biomedical applications are reviewed herein, covering their potential use in disease diagnosis and therapy. Some of the AuNP-based systems that are approved for clinical trials are also discussed, as well as the potential health threats of AuNPs and some strategies that can be used to improve their biocompatibility. The reviewed studies offer proof of principle that AuNP-based systems could potentially be used alone or in combination with the conventional systems to improve their efficacy.

Evolution of the protein corona affects macrophage polarization

When nanoparticles (NPs) come into contact with bioenvironments, a protein corona forms on the NP surface. Previous reports showed that the constituents of the corona change with time. However, how different protein corona compositions influence cells, especially immune cells, has received less attention. Macrophages are important immune cells that can be polarized into a pro-inflammatory (M1) or anti-inflammatory (M2) phenotype. In this study, AuNPs were incubated with human plasma for different periods to obtain time-related AuNP-coronas, and the influences of time-related AuNP-coronas on macrophage polarization were investigated. The macrophage morphology, biomarkers, cytokine secretion studies show that the pristine AuNPs and 4 h-AuNP-corona induced macrophage cells into M2 phenotype, while the co-incubation of 12 h-AuNP-corona and macrophage cells result in M1 phenotype. Further proteomic analysis showed that the compositions of protein corona were changing constantly after AuNPs contacted with plasma. When the incubation time increased to 12 h, the immune proteins in protein corona were increased significantly, which play a key role in modulation of the different macrophages polarization. Our findings demonstrated that plasma incubation time is an important parameter that needs to be taken into account in the study of nano-immune interactions and safe use of NPs in biological systems. Moreover, our finding can be a new efficient strategy for activating inflammatory or anti-inflammatory in medical treatment.

Gold Nanostars with Reduced Fouling Facilitate Small Molecule Detection in the Presence of Protein

Gold nanoparticles have the potential to be used in biomedical applications from diagnostics to drug delivery. However, interactions of gold nanoparticles with different biomolecules in the cellular environment result in the formation of a “protein corona”—a layer of protein formed around a nanoparticle, which induces changes in the properties of nanoparticles. In this work we developed methods to reproducibly synthesize spheroidal and star-shaped gold nanoparticles, and carried out a physico-chemical characterization of synthesized anionic gold nanospheroids and gold nanostars through transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential (ZP), nanoparticles tracking analysis (NTA), ultraviolet-visible (UV–Vis) spectroscopy and estimates of surface-enhanced Raman spectroscopy (SERS) signal enhancement ability. We analyzed how they interact with proteins after pre-incubation with bovine serum albumin (BSA) via UV–Vis, DLS, ZP, NTA, SERS, cryogenic TEM (cryo-TEM) and circular dichroism (CD) spectroscopy. The tests demonstrated that the protein adsorption on the particles’ surfaces was different for spheroidal and star shaped particles. In our experiments, star shaped particles limited the protein corona formation at SERS “hot spots”. This benefits the small-molecule sensing of nanostars in biological media. This work adds more understanding about protein corona formation on gold nanoparticles of different shapes in biological media, and therefore guides design of particles for studies in vitro and in vivo.

Targeted Chemotherapy Delivery via Gold Nanoparticles: A Scoping Review of In Vivo Studies

In the field of oncology, a lot of improvements in nanotechnology creates support for better diagnosis and therapeutic opportunities, and due to their physical and chemical properties, gold nanoparticles are highly applicable. We performed a literature review on the studies engaging the usage of gold nanoparticles on murine models with a focus on the type of the carrier, the chemotherapy drug, the target tumoral tissue and outcomes. We identified fifteen studies that fulfilled our search criteria, in which we analyzed the synthesis methods, the most used chemotherapy conjugates of gold nanoparticles in experimental cancer treatment, as well as the improved impact on tumor size and system toxicity. Due to their intrinsic traits, we conclude that chemotherapy conjugates of gold nanoparticles are promising in experimental cancer treatment and may prove to be a safer and improved therapy option than current alternatives.

A Review on Biosensors and Nanosensors Application in Agroecosystems

Previous decades have witnessed a lot of challenges that have provoked a dire need of ensuring global food security. The process of augmenting food production has made the agricultural ecosystems to face a lot of challenges like the persistence of residual particles of different pesticides, accretion of heavy metals, and contamination with toxic elemental particles which have negatively influenced the agricultural environment. The entry of such toxic elements into the human body via agricultural products engenders numerous health effects such as nerve and bone marrow disorders, metabolic disorders, infertility, disruption of biological functions at the cellular level, and respiratory and immunological diseases. The exigency for monitoring the agroecosystems can be appreciated by contemplating the reported 220,000 annual deaths due to toxic effects of residual pesticidal particles. The present practices employed for monitoring agroecosystems rely on techniques like gas chromatography, high-performance liquid chromatography, mass spectroscopy, etc. which have multiple constraints, being expensive, tedious with cumbersome protocol, demanding sophisticated appliances along with skilled personnel. The past couple of decades have witnessed a great expansion of the science of nanotechnology and this development has largely facilitated the development of modest, quick, and economically viable bio and nanosensors for detecting different entities contaminating the natural agroecosystems with an advantage of being innocuous to human health. The growth of nanotechnology has offered rapid development of bio and nanosensors for the detection of several composites which range from several metal ions, proteins, pesticides, to the detection of complete microorganisms. Therefore, the present review focuses on different bio and nanosensors employed for monitoring agricultural ecosystems and also trying to highlight the factor affecting their implementation from proof-of-concept to the commercialization stage.

Efficient Protein Transfection by Swarms of Chemically Powered Plasmonic Virus-Sized Nanorobots

Transfection is based on nonviral delivery of nucleic acids or proteins into cells. Viral approaches are being used; nevertheless, their translational capacity is nowadays decreasing due to persistent fear of their safety, therefore creating space for the field of nanotechnology. However, nanomedical approaches introducing static nanoparticles for the delivery of biologically active molecules are very likely to be overshadowed by the vast potential of nanorobotics. We hereby present a rapid nonviral transfection of protein into a difficult-to-transfect prostate cancer cell line facilitated by chemically powered rectangular virus-sized (68 nm × 33 nm) nanorobots. The enhanced diffusion of these biocompatible nanorobots is the key to their fast internalization into cells, happening in a matter of minutes and being up to 6-fold more efficient compared to static nanorobots in a nonfueled environment. The Au/Ag plasmonic nature of these nanorobots makes them simply traceable and allows for their detailed subcellular localization. Protein transfection mediated by such nanorobots is an important step forward, challenging the field of nanomedicine and having potential in future translational medical research.

Oligoarginine Peptide Conjugated to BSA Improves Cell Penetration of Gold Nanorods and Nanoprisms for Biomedical Applications

Gold nanoparticles (AuNPs) have been shown to be outstanding tools for drug delivery and biomedical applications, mainly owing to their colloidal stability, surface chemistry, and photothermal properties. The biocompatibility and stability of nanoparticles can be improved by capping the nanoparticles with endogenous proteins, such as albumin. Notably, protein coating of nanoparticles can interfere with and decrease their cell penetration. Therefore, in the present study, we functionalized albumin with the r₈ peptide (All-D, octaarginine) and used it for coating NIR-plasmonic anisotropic gold nanoparticles. Gold nanoprisms (AuNPrs) and gold nanorods (AuNRs) were coated with bovine serum albumin (BSA) previously functionalized using a cell penetrating peptide (CPP) with the r₈ sequence (BSA-r₈). The effect of the coated and r₈-functionalized AuNPs on HeLa cell viability was assessed by the MTS assay, showing a low effect on cell viability after BSA coating. Moreover, the internalization of the nanostructures into HeLa cells was assessed by confocal microscopy and transmission electron microscopy (TEM). As a result, both nanoconstructs showed an improved internalization level after being capped with BSA-r₈, in contrast to the BSA-functionalized control, suggesting the predominant role of CPP functionalization in cell internalization. Thus, our results validate both novel nanoconstructs as potential candidates to be coated by endogenous proteins and functionalized with a CPP to optimize cell internalization. In a further approach, coating AuNPs with CPP-functionalized BSA can broaden the possibilities for biomedical applications by combining their optical properties, biocompatibility, and cell-penetration abilities.

Application of the catalytic activity of gold nanoparticles for development of optical aptasensors

Biosensor technology is considered to be a great alternative in analytical techniques over the conventional methods. Among many recently developed techniques and devices, aptasensors are interesting because of their high specificity, selectivity and sensitivity. Combining aptamer as a biological recognition element with gold nanoparticles (AuNPs) as probe, are becoming more general owing to their beneficial properties, including low cost and ability to analyze specific targets on-site and using naked eye. Hydrogen bonds, nucleic acid hybridization, aptamer-target and antigen-antibody binding, Raman signature, enzyme inhibition, and enzyme-mimicking activity are main different sensing strategies exploited in AuNPs-based optical aptasensors. In this review article, we discussed the recent advances in optical aptasensors with a special emphasis on the catalytic activity property of AuNPs.

Internalisation and Biological Activity of Nucleic Acids Delivering Cell-Penetrating Peptide Nanoparticles Is Controlled by the Biomolecular Corona

Nucleic acid molecules can be transferred into cells to alter gene expression and, thus, alleviate certain pathological conditions. Cell-penetrating peptides (CPPs) are vectors that can be used for transfecting nucleic acids as well as many other compounds. CPPs associate nucleic acids non-covalently, forming stable nanoparticles and providing efficient transfection of cells in vitro. However, in vivo, expected efficiency is achieved only in rare cases. One of the reasons for this discrepancy is the formation of protein corona around nanoparticles, once they are exposed to a biological environment, e.g., blood stream. In this study, we compared protein corona of CPP-nucleic acid nanoparticles formed in the presence of bovine, murine and human serum. We used Western blot and mass-spectrometry to identify the major constituents of protein corona forming around nanoparticles, showing that proteins involved in transport, haemostasis and complement system are its major components. We investigated physical features of nanoparticles and measured their biological efficiency in splice-correction assay. We showed that protein corona constituents might alter the fate of nanoparticles in vivo, e.g., by subjecting them to phagocytosis. We demonstrated that composition of protein corona of nanoparticles is species-specific that leads to dissimilar transfection efficiency and should be considered while developing delivery systems for nucleic acids.

Protection against proteolysis of a targeting peptide on gold nanostructures

Cell targeting has been considered an important strategy in diagnostic and therapeutic applications. Among different targeting units, peptides have emerged for their ability to bind to many different cellular targets, their scarce immunogenicity and the possibility of introducing multiple copies on nanosystems, providing high avidity for the target. However, their sensitivity to proteases strongly limits their applications in vivo. Here, we show that when presented on the surface of nanostructures, peptide stability to proteolysis is strongly improved without reducing the targeting activity. We prepared plasmonic nanostructures functionalized with a dodecapeptide (GE11) which targets EGFR, a protein overexpressed on different types of tumors. Two types of nanosystems were prepared in which the targeting unit was either directly linked to gold nanoparticles or through a PEG chain, resulting in a different peptide density on the surface of nanostructures. The peptide was rapidly degraded in 20% human serum or in the presence of isolated serine proteases, whereas no significant proteolytic fragments were detected during incubation of the nanosystems and after 24 h digestion, the nanostructures maintained their targeting activity and selectivity on colon cancer cells. Molecular dynamic calculations of the interaction of the nanostructure with chymotrypsin suggest that the formation of the enzyme-peptide complex, the first step in the mechanism of peptide hydrolysis, is highly unlikely because of the constraint imposed by the link of the peptide to the nanoparticle. These results support the utilization of peptides as active targeting units in nanomedicine.

Adsorption of bovine serum albumin on gold nanoprisms: interaction and effect of NIR irradiation on protein corona

Because of their photothermal properties, gold nanoparticles (AuNPs) have gained attention regarding their use in drug delivery and therapeutic applications. In this sense, it is interesting to consider their interactions with biologically available proteins, such as serum albumin, as well as the effects of irradiation and photothermal conversion on the protein structure that can lead to a loss of function or generate an immune response. Gold nanoprisms (AuNPrs) have gained interest due to their low toxicity, ease of synthesis, and excellent stability, promoting their use in bioapplications such as surface-enhanced Raman spectroscopy (SERS), drug delivery, and photothermal therapy. The interaction between AuNPrs, with plasmon bands centred in the near-infrared region (NIR), and bovine serum albumin (BSA) has not been explored yet. UV-Vis spectroscopy, dynamic light scattering (DLS) and fluorescence spectroscopy were used to study the interaction between AuNPrs and BSA in addition to estimation of the adsorption rate and kinetic and thermodynamic parameters (K, ΔH°, ΔG°, ΔS°, and Ea) using adsorption isotherms and Langmuir and Freundlich models. The results suggest spontaneous cooperative binding in multilayer adsorption, achieved by the chemisorption of BSA on the AuNPr surface through the S-Au interaction, as confirmed by Raman spectroscopy. On the other hand, the photothermal conversion efficiency (PE) of the coated nanoparticles after NIR irradiation was assessed, resulting in a slight decrease in the PE of BSA coated on AuNPrs in comparison with that of noncapped nanoparticles. The effect of the irradiation on the protein conformation of capped nanoparticles was also assessed; circular dichroism showed BSA unfolding upon interaction with AuNPrs, with a decrease in the α-helix and β-sheet contents, as well as an increase in random coil conformations. Changes in the Raman spectrum suggest a modification of the disposition of the protein residues exposed to the gold surface after NIR irradiation; but at the secondary structure level, no relevant changes were observed. This provides possibilities for the use of NPs-BSA for bioapplications based on the photothermal effect promoted by laser irradiation, since the biological identity of the protein is preserved after NIR irradiation.

Gold Nanoparticles in Cancer Theranostics

Conventional cancer treatments, such as surgical resection, radiotherapy, and chemotherapy, have achieved significant progress in cancer therapy. Nevertheless, some limitations (such as toxic side effects) are still existing for conventional therapies, which motivate efforts toward developing novel theranostic avenues. Owning many merits such as easy surface modification, unique optical properties, and high biocompatibility, gold nanoparticles (AuNPs and GNPs) have been engineered to serve as targeted delivery vehicles, molecular probes, sensors, and so on. Their small size and surface characteristics enable them to extravasate and access the tumor microenvironment (TME), which is a promising solution to realize highly effective treatments. Moreover, stimuli-responsive properties (respond to hypoxia and acidic pH) of nanoparticles to TME enable GNPs’ unrivaled control for effective transport of therapeutic cargos. In this review article, we primarily introduce the basic properties of GNPs, further discuss the recent progress in gold nanoparticles for cancer theranostics, with an additional concern about TME stimuli-responsive studies.

Research progress and application opportunities of nanoparticle-protein corona complexes

Nanoparticles (NPs) can be used to design for nanomedicines with different chemical surface properties owing to their size advantages and the capacity of specific delivery to targeted sites in organisms. The discovery of the presence of protein corona (PC) has changed our classical view of NPs, stimulating researchers to investigate the in vivo fate of NPs as they enter biological systems. Both NPs and PC have their specificity but complement each other, so they should be considered as a whole. The formation and characterization of NP-PC complexes provide new insights into the design, functionalization, and application of nanocarriers. Based on progress of recent researches, we reviewed the formation, characterization, and composition of the PC, and introduced those critical factors influencing PC, simultaneously expound the effect of PC on the biological function of NPs. Especially we put forward the opportunities and challenges when NP-PC as a novel nano-drug carrier for targeted applications. Furthermore, we discussed the pros versus cons of the PC, as well as how to make better PC in the future application of NPs.