Prevent Protein Adsorption Research Articles

Lyso-phosphatidylcholine as an interfacial stabilizer for parenteral monoclonal antibody formulations

Therapeutic proteins suffer from physical and chemical instability in aqueous solution. Polysorbates and poloxamers are often added for protection against interfacial stress to prevent protein aggregation and particle formation. Previous studies have revealed that the hydrolysis and oxidation of polysorbates in parenteral formulations can lead to the formation of free fatty acid particles, insufficient long-term stabilization, and protein oxidation. Poloxamers, on the other hand, are considered to be less effective against protein aggregation. Here we investigated two lyso-phosphatidylcholines (LPCs) as potential alternative surfactants for protein formulations, focusing on their physicochemical behavior and their ability to protect against the formation of monoclonal antibody particles during mechanical stress.The hemolytic activity of LPC was tested in varying ratios of plasma and buffer mixtures. LPC effectively stabilized mAb formulations when shaken at concentrations several orders of magnitude below the onset of hemolysis, indicating that the potential for erythrocyte damage by LPC is non-critical. LPC formulations subjected to mechanical stress through peristaltic pumping exhibited comparable protein particle formation to those containing polysorbate 80 or poloxamer 188. Profile analysis tensiometry and dilatational rheology indicated that the stabilizing effect likely arises from the formation of a viscoelastic film at approximately the CMC. Data gathered from concentration-gradient multi-angle light scattering and isothermal titration calorimetry support this finding. Surfactant desorption was evaluated through sub-phase exchange experiments. While LPCs readily desorbed from the interface, resorption occurred rapidly enough in the bulk solution to prevent protein adsorption. Overall, LPCs behave similarly to polysorbate with respect to interfacial stabilization and show promise as a potential substitute for polysorbate in parenteral protein formulations.

Short Zwitterionic Sulfobetaine-Modified Silica Nanoparticles: Is Neutrality Possible?

Zwitterionic coatings are an efficient strategy for preventing biomolecule adsorption and enhancing nanoparticle stability in solution. The properties of zwitterions and other antifouling materials, including suppression of nonspecific adsorption and improved colloidal stability of nanoparticles, are believed to derive from their electroneutral and highly hydrophilic nature. Among different zwitterions, short sulfobetaines have been demonstrated to be effective in preventing protein adsorption onto several nanoparticles and providing enhanced colloidal stability. Although zwitterionic sulfobetaine silane (ZS) is electrically neutral, the negatively charged zwitterionic sulfobetaine-functionalized silica nanoparticles (ZS@SiO2NPs) exhibit a similar ζ-potential to nonfunctionalized silica nanoparticles (SiO2NPs). In this work, we present a thorough comprehension of the surface properties of ZS@SiO2NPs, which encompasses the development of meticulous functionalization procedures, detailed characterization approaches, and cutting-edge modeling to address the questions that persist regarding the surface features of ZS@SiO2NPs. The negative charge of ZS@SiO2NPs is due to the stabilization of siloxide from residual surface silanols by the quaternary amine in the sulfobetaine structure. Consequently, we infer that zero-charge ZS@SiO2NPs are unlikely to be obtained since this stabilization increases the dissociation degree of surface silanols, increasing the overall structure negative charge. Additionally, colloidal stability was evaluated in different pH and ionic strength conditions, and it was found that ZS@SiO2NPs are more stable at higher ionic strengths. This suggests that the interaction between ZS and salt ions prevents the aggregation of ZS@SiO2NPs. Together, these results shed light on the nature of the ZS@SiO2NP negative charge and possible sources for the remarkable colloidal stability of zwitterionic nanoparticles in complex media.

Quantification of Poly(ethylene glycol) Crowding on Nanodiamonds toward Quantum Biosensor for Improved Prevention Effects on Protein Adsorption and Lung Accumulation.

Nanometer-sized diamonds (NDs) containing nitrogen vacancy centers have garnered significant attention as potential quantum sensors for reading various types of physicochemical information in vitro and in vivo. However, NDs intrinsically aggregate when placed in biological environments, hampering their sensing capacities. To address this issue, the grafting of hydrophilic polymers onto the surface of NDs has been demonstrated considering their excellent ability to prevent protein adsorption. To this end, crowding of the grafted chains plays a crucial role because it is directly associated with the antiadsorption effect of proteins; however, its quantitative evaluation has not been reported previously. In this study, we graft poly(ethylene glycol) (PEG) with various molecular weights onto NDs, determine their crowding using a gas adsorption technique, and disclose the cross-correlation between the pH in the grafting reaction, crowding density, molecular weight, and the prevention effect on protein adsorption. PEG-grafted NDs exhibit a pronounced effect on the prevention of lung accumulation after intravenous injection in mice. PEG crowding was compared to that calculated by using a diameter determined by dynamic light scattering (DLS) assuming a sphere.

Constructing a Hydrophilic Microsensor for High-Antifouling Neurotransmitter Dopamine Sensing.

Real-time sensing of dopamine is essential for understanding its physiological function and clarifying the pathophysiological mechanism of diseases caused by impaired dopamine systems. However, severe fouling from nonspecific protein adsorption, for a long time, limited conventional neural recording electrodes concerning recording stability. This study reported a high-antifouling nanocrystalline boron-doped diamond microsensor grown on a carbon fiber substrate. The antifouling properties of this diamond sensor were strongly related to the grain size (i.e., nanocrystalline and microcrystalline) and surface terminations (i.e., oxygen and hydrogen terminals). Experimental observations and molecular dynamics calculations demonstrated that the oxygen-terminated nanocrystalline boron-doped diamond microsensor exhibited enhanced antifouling characteristics against protein adsorption, which was attributed to the formation of a strong hydration layer as a physical and energetic barrier that prevents protein adsorption on the surface. This finally allowed for in vivo monitoring of dopamine in rat brains upon potassium chloride stimulation, thus presenting a potential solution for the design of next-generation antifouling neural recording sensors. Experimental observations and molecular dynamics calculations demonstrated that the oxygen-terminated nanocrystalline boron-doped diamond (O-NCBDD) microsensor exhibited ultrahydrophilic properties with a contact angle of 4.9°, which was prone to forming a strong hydration layer as a physical and energetic barrier to withstand the adsorption of proteins. The proposed O-NCBDD microsensor exhibited a high detection sensitivity of 5.14 μA μM-1 cm-2 and a low detection limit of 25.7 nM. This finally allowed for in vivo monitoring of dopamine with an average concentration of 1.3 μM in rat brains upon 2 μL of potassium chloride stimulation, thus presenting a potential solution for the design of next-generation antifouling neural recording sensors.

Effect of Lipid Corona on Phenylalanine-Functionalized Gold Nanoparticles to Develop Stable and Corona-Free Systems.

Conventional gold nanoparticles (Au NPs) have many limitations, such as aggregation and subsequent precipitation in the medium of high ionic strength and protein molecules. Furthermore, when exposed to biological fluids, nanoparticles form a protein corona, which controls different biological processes such as the circulation lifetime, drug release profile, biodistribution, and in vivo cellular distribution. These limitations reduce the functionality of Au NPs in targeted delivery, bioimaging, gene delivery, drug delivery, and other biomedical applications. To circumvent these problems, there are numerous attempts to design corona-free and stable nanoparticles. Here, we report for the first time that lipid corona (coating of lipid) formation on phenylalanine-functionalized Au NPs (AuPhe NPs) imparts excellent stability against the high ionic strength of bivalent metal ions, amino acids, and proteins of different charges as compared to bare nanoparticles. Moreover, this work is focused on the ability of lipid corona formation on AuPhe NPs to prevent protein adsorption in the presence of cell culture medium (CCM), oppositely charged protein (e.g., histone 3), and human serum albumin (HSA). The results demonstrate that the lipid corona successfully protects the AuPhe NPs from protein adsorption, leading to the development of corona-free character. This unique achievement has profound implications for enhancing the biomedical utility and safety of these nanoparticles.

Experimental and computational techniques to investigate the protein resistance of zwitterionic polymers.

Most surfaces undergo non-specific protein adsorption upon direct contact with protein-containing environments, resulting in the formation of a protein corona, and the nature and composition of the corona affect the properties of the material. Zwitterionic polymers have oppositely charged groups in their repeating units, which facilitate the formation of a hydration layer on the surface through electrostatic interactions. The hydration layer possesses a strong water-binding ability and can prevent protein adsorption. Therefore, the hydration effect of zwitterionic polymers has become a research focus, and many researchers have investigated this mechanism using experimental and computational methods. This paper reviews the experimental techniques and simulation methods to study the hydration effect of zwitterionic polymers and the advantages and disadvantages of different techniques are discussed.

Capillary electrophoresis-mass spectrometry for intact protein analysis: Pharmaceutical and biomedical applications (2018-March 2023).

Capillary electrophoresis is recognized as a valued separation technique for its high separation efficiency, low sample consumption, good economic and ecological aspects, reproducibility, and complementarity to traditional liquid chromatography techniques. Capillary electrophoresis experiments are generally performed utilizing optical detection, such as ultraviolet or fluorescence detectors. However, in order to provide structural information, capillary electrophoresis hyphenated to highly sensitive and selective mass spectrometry has been developed to overcome the limitations of optical detections. Capillary electrophoresis-mass spectrometry is increasingly popular in protein analysis, including biopharmaceutical and biomedical research. It is frequently applied for the determination of physicochemical and biochemical parameters of proteins, offers excellent performance for in-depth characterizations of biopharmaceuticals at various levels of analysis, and has been also already proven as a promising tool in biomarker discovery. In this review, we focus on the possibilities and limitations of capillary electrophoresis-mass spectrometry for protein analysis at their intact level. Various capillary electrophoresis modes and capillary electrophoresis-mass spectrometry interfaces, as well as approaches to prevent protein adsorption and to enhance sample loading capacity, are discussed and the recent (2018-March 2023) developments and applications in the field of biopharmaceutical and biomedical analysis are summarized.

DPA-Zinc around Polyplexes Acts Like PEG to Reduce Protein Binding While Targeting Cancer Cells.

Gene therapy holds great promise as an effective treatment for many diseases of genetic origin. Gene therapy works by employing cationic polymers, liposomes, and nanoparticles to condense DNA into polyplexes via electronic interactions. Then, a therapeutic gene is introduced into target cells, thereby restoring or changing cellular function. However, gene transfection efficiency remains low in vivo due to high protein binding, poor targeting ability, and substantial endosomal entrapment. Artificial sheaths containing PEG, anions, or zwitterions can be introduced onto the surface of gene carriers to prevent interaction with proteins; however, they reduce the cellular uptake efficacy, endosomal escape, targeting ability, thereby, lowering gene transfection. Here, it is reported that linking dipicolylamine-zinc (DPA-Zn) ions onto polyplex nanoparticles can produce a strong hydration water layer around the polyplex, mimicking the function of PEGylation to reduce protein binding while targeting cancer cells, augmenting cellular uptake and endosomal escape. The polyplexes with a strong hydration water layer on the surface can achieve a high gene transfection even in a 50% serum environment. This strategy provides a new solution for preventing protein adsorption while improving cellular uptake and endosomal escape.

A Commercial Nonbinding Surface Effectively Reduces Fibrinogen Adsorption but Does Not Prevent Platelet Adhesion to Fibrinogen.

A commercial nonbinding surface effectively prevents protein adsorption; however, the platelet phenotype on this surface has yet to be defined. This study evaluates platelet adhesion and adsorption of several plasma/extracellular matrix (ECM) proteins to the nonbinding surface compared to other commonly used nontreated and high-binding surfaces. Platelet adhesion to uncoated microplates and those coated with fibrinogen or collagen is quantified by colorimetric assay. The binding capacity of the examined surfaces for plasma/ECM proteins is evaluated by measuring the relative and absolute protein adsorption. Compared to other surfaces, the nonbinding surface effectively prevents platelet adsorption, i.e. by 61-93% (Enzyme-Linked Immunosorbent Assay, ELISA), and reduces platelet adhesion, i.e. by 92%, when not coated with any protein. The nonbinding surface also decreases platelet deposition on collagen (up to 31%), but not fibrinogen. The nonbinding surface seems to be more of a low-fouling than nonfouling material, as it is able to reduce fibrinogen adsorption but not prevent platelet adhesion to fibrinogen. This feature should be considered when using the nonbinding surface for in vitro platelet testing.

A multifunctional bio-patch crosslinked with glutaraldehyde for enhanced mechanical performance, anti-coagulation properties, and anti-calcification properties.

Bio-patches for the treatment of valvular disease have been evaluated in clinical trials. It has been shown that failure of these devices, occurring within a few years of implantation, may be due to cytotoxicity, immune response, calcification and thrombosis. Some of these effects may be due to the glutaraldehyde crosslinking process used in the preparation of the materials. A number of studies have focused on strategies to control calcification, while others have concentrated on the prevention of micro-thrombus formation. In the present work, we have introduced amino-terminated poly(ethylene glycol) (NH2-PEG-NH2) as an intermolecular bridge, which not only eliminates free aldehyde groups to prevent calcification, but also introduces sites for the attachment of anticoagulant molecules. Furthermore, PEG, itself a hydrophilic polymer with good biocompatibility, may effectively prevent protein adsorption in the early stages of blood contact leading to thrombus formation. After further covalent attachment of heparin, modified bovine pericardium (BP) showed strong anti-calcification (calcium content: 39.3 ± 3.1 μg mg-1) and anti-coagulation properties (partial thromboplastin time: >300 s). The biocompatibility and mechanical properties, important for clinical use, were also improved by modification. The strategy used in this work includes new ideas and technologies for the improvement of valve products used in the clinic.

Differential Surface Adsorption Phenomena for Conventional and Novel Surfactants Correlates with Changes in Interfacial mAb Stabilization.

Protein adsorption on surfaces can result in loss of drug product stability and efficacy during the production, storage, and administration of protein-based therapeutics. Surface-active agents (excipients) are typically added in protein formulations to prevent undesired interactions of proteins on surfaces and protein particle formation/aggregation in solution. The objective of this work is to understand the molecular-level competitive adsorption mechanism between the monoclonal antibody (mAb) and a commercially used excipient, polysorbate 80 (PS80), and a novel excipient, N-myristoyl phenylalanine-N-polyetheramine diamide (FM1000). The relative rate of adsorption of PS80 and FM1000 was studied by pendant bubble tensiometry. We find that FM1000 saturates the interface faster than PS80. Additionally, the surface-adsorbed amounts from X-ray reflectivity (XRR) measurements show that FM1000 blocks a larger percentage of interfacial area than PS80, indicating that a lower bulk FM1000 surface concentration is sufficient to prevent protein adsorption onto the air/water interface. XRR models reveal that with an increase in mAb concentration (0.5-2.5 mg/mL: IV based formulations), an increased amount of PS80 concentration (below critical micelle concentration, CMC) is required, whereas a fixed value of FM1000 concentration (above its relatively lower CMC) is sufficient to inhibit mAb adsorption, preventing mAb from co-existing with surfactants on the surface layer. With this observation, we show that the CMC of the surfactant is not the critical factor to indicate its ability to inhibit protein adsorption, especially for chemically different surfactants, PS80 and FM1000. Additionally, interface-induced aggregation studies indicate that at minimum surfactant concentration levels in protein formulations, fewer protein particles form in the presence of FM1000. Our results provide a mechanistic link between the adsorption of mAbs at the air/water interface and the aggregation induced by agitation in the presence of surfactants.

Interactive Hemocompatible Nanocoating to Prevent Surface‐Induced Coagulation in Medical Devices

AbstractInterfacing blood with any artificial surface instantly triggers the activation of coagulation at the interface, posing a risk of adverse thromboembolic complications. Immediately upon contact, blood proteins adsorb to the surface turning it into an active prothrombogenic and proinflammatory interface promoting the activation of platelets and the coagulation cascade. Here, an interactive hemocompatible nanocoating is designed that synergistically combines antifouling polymer brushes with the activity of an anti‐FXIIa antibody to tackle the two main causes of surface‐induced coagulation. The brushes provide a passive layer rendering the surface stealth and non‐thrombogenic against blood activation. Furthermore, as soon as traces of FXIIa arise, the coating immediately and specifically scavenges it, thus actively switching‐off contact activation right at the beginning. Moreover, a means is developed to translate this coating to a broad range of polymeric surfaces commonly used in medical devices. The coated surfaces prevent protein adsorption and provide a barrier to bacterial colonization while being capable of capturing biologically relevant concentrations of FXIIa. Notably, the coating completely prevents the formation of clots on the surface when exposed to blood. Thus, the interactive anti‐FXIIa nanocoating provides a new avenue to improve the hemocompatibility of medical devices in a safe and efficient manner.

Microfluidic Production of Zwitterion Coating Microcapsules with Low Foreign Body Reactions for Improved Islet Transplantation.

Islet transplantation is a promising strategy for type 1 diabetes mellitus (T1DM) treatment, whereas implanted-associated foreign body reaction (FBR) usually induces the necrosis of transplanted islets and leads to the failure of glycemic control. Benefiting from the excellent anti-biofouling property of zwitterionic materials and their successful application in macroscopic implanted devices, microcapsules with zwitterionic coatings may be promising candidates for islet encapsulation. Herein, a series of zwitterion-coated core-shell microcapsules is fabricated (including carboxybetaine methacrylate [CBMA]-coated gelatin methacrylate [GelMA] [CBMA-GelMA], sulfobetaine methacrylate [SBMA]-coated GelMA [SBMA-GelMA], and phosphorylcholine methacrylate [MPC]-coated GelMA [MPC-GelMA]) by one-step photopolymerization of inner GelMA and outer zwitterionic monomers via a handmade two-fluid microfluidic device and it is demonstratedthat they can effectively prevent protein adsorption, cell adhesion, and inflammation in vitro. Interestingly, the zwitterionic microcapsules successfully resist FBR in C57BL/6 mice after intraperitoneal implantation for up to 4 months. After successfully encapsulating xenogeneic rat islets in the SBMA-GelMA microcapsules, sustained normoglycemia is further validated in streptozotocin (STZ)-induced mice for up to 3 months. The zwitterion-modified microcapsule using a microfluidic device may represent a platform for cell encapsulation treatment for T1DM and other hormone-deficient diseases.

Surface Hydration and Antifouling Activity of Zwitterionic Polymers.

It is believed that the strong surface hydration of zwitterionic polymers leads to excellent antifouling properties. This Perspective presents the recent developments in studies on such surface hydration in situ using sum frequency generation (SFG) vibrational spectroscopy. SFG research provides direct molecular level evidence that zwitterionic polymers have strong surface hydration, which prevents protein adsorption and marine animal attachment. The salt effect and protein interaction on surface hydration of zwitterionic polymers have also been examined using SFG. Possible future research directions on surface hydration of new zwitterionic polymers including zwitterionic hydrogels, copolymers, and mixed charged polymers are discussed. It is also important to combine experimental SFG studies with computer simulations to further elucidate the surface hydration to understand antifouling mechanisms.

The degradation of poloxamer 188 in buffered formulation conditions

Poloxamer 188 (P188) as a non-ionic surfactant is used in proteinaceous formulations to prevent protein adsorption to hydrophobic surfaces and unfolding at interfaces, preventing the formation of aggregates and particles. Its chemical intactness is crucial to the stability of drug products due to its protecting effects at interfaces. In order to identify and mitigate potential risks that might cause the degradation of P188 during the manufacturing process and storage, in the current work, the stability of P188 was investigated by forced degradation in buffered formulation conditions via oxidation and thermal stress conditions. The process of degradation was monitored through the dedicated liquid adsorption chromatography (LAC) with high sensitivity, and the degradants were characterized by high-resolution mass spectrometry. Results suggest that the vulnerability of P188 is largely related to the buffer conditions. Histidine promotes degradation in the presence of hydroxyl radicals but inhibits the degradation in the presence of H2O2 and alkyl radicals. In thermal stress conditions, histidine protects P188 from degradation at 40 °C, and activates its decay only at higher temperature, like 60 °C.

Poly(methyl methacrylate) surface grafted with poly(2-ethyl-2-oxazoline) using tea polyphenol as linker molecule

Studies of antifouling materials have been focused on substituting synthetic materials with bio-based materials, which are essentially derived from plants and suitably categorized as ‘green’ and renewable materials. Gallic acid (GA), which exists abundantly in tea and other plants, has important biological and pharmacological properties. In this study, GA was used as a linker molecule to combine poly(2-ethyl-2-oxazoline) (PEtOx) and poly(methyl methacrylate) (PMMA). Firstly, bio-based polymer (PEtOx-GA) was synthesized and then was reacted with the poly(ethyleneimine)-modified PMMA substrate (PEI-S) to form the functional film (PEtOx-GA-PEI-S) via Schiff-base and Michael addition reactions. The PEtOx-GA-PEI-S functional film prevented protein adsorption, as demonstrated by water contact angle testing and an adsorption experiment with bovine serum albumin (BSA) protein, and the mass of adsorbed BSA was reduced by ~70%. This study focuses on the recent developments with bio-based materials that are employed for functional film synthesis and indicate that PEtOx-GA-PEI-S functional film is a highly promising candidate for biomedical antifouling applications.

Enzyme mimetic microgel coating for endogenous nitric oxide mediated inhibition of platelet activation

Nitric oxide (NO) continuously generated by healthy endothelium prevents platelet activation and maintains vascular homeostasis. However, when artificial surfaces, like of extracorporeal membrane oxygenator comes in contact with blood, protein adsorption and thereby platelet activation takes place, which eventually leads to thrombus formation. To overcome this, we present an antifouling microgel coating mimicking the function of enzyme glutathione peroxidase to endogenously generate NO in the blood plasma from endogenous NO-donors and maintain a physiological NO flux. Microgels are synthesized by copolymerization of highly hydrophilic N–(2–hydroxypropyl)methacrylamide (HPMA) and glycidyl methacrylate (GMA) with diselenide crosslinks. For immobilization of the microgels on hydrophobic poly(4-methylpentene) (TPX) membranes bioengineered amphiphilic anchor peptides with free thiols are used. The anchor peptide attaches to the TPX membranes by hydrophobic interactions while the free thiols are presented for crosslinking with the microgels. The hydrophilic nature of the microgel coating prevents protein adsorption while the reversible diselenide bridges make the microgels responsive to the reducing environment and lead to the formation of reactive selenols/selenolates. The generated selenols/selenolates provide an efficient and sustained NO-release from endogenous S-nitrosothiols (RSNOs) mimicking the enzymatic function of glutathione peroxidase. On exposure to the whole blood, the microgel coating inhibited platelet activation and prolonged the blood clotting time.

Superamphiphilic TiO2 Composite Surface for Protein Antifouling.

Unwanted protein adsorption deteriorates fouling processes and reduces analytical device performance. Wettability plays an important role in protein adsorption by affecting interactions between proteins and surfaces. However, the principles of protein adsorption are not completely understood, and surface coatings that exhibit resistance to protein adsorption and long-term stability still need to be developed. Here, a nanostructured superamphiphilic TiO2 composite (TiO2 /SiO2 ) coating that can effectively prevent nonspecific protein adsorption on water/solid interfaces is reported. The confined water on the superamphiphilic surface enables a low adhesion force and the formation of an energy barrier that plays a key role in preventing protein adsorption. This adaptive design protects the capillary wall from fouling in a harsh environment during the bioanalysis of capillary electrophoresis and is further extended to applications in multifunctional microfluidics for liquid transportation. This facile approach is not only perfectly applied in channels with complicated configurations but may also offer significant insights into the design of advanced superwetting materials to control biomolecule adhesion in biomedical devices, microfluidics, and biological assays.

Effects of Side-Chain Spacing and Length on Hydration States of Poly(2-methoxyethyl acrylate) Analogues: A Molecular Dynamics Study.

Hydration states of polymers are known to directly influence the adsorption of biomolecules. Particularly, intermediate water (IW) has been found able to prevent protein adsorption. Experimental studies have examined the IW content and nonthrombogenicity of poly(2-methoxyethyl acrylate) analogues with different side-chain spacings and lengths, which are HPx (x is the number of backbone carbons in a monomer) and PMCyA (y is the number of carbons in-between ester and ether oxygens of the side-chain) series, respectively. HPx was reported to possess more IW content but lower nonthrombogenicity compared to PMCyA with analogous composition. To understand the reason for the conflict, molecular dynamics simulations were conducted to elucidate the difference in the properties between the HPx and PMCyA. Simulation results showed that the presence of more methylene groups in the side chain more effectively prohibits water penetration in the polymer than those in the polymer backbone, causing a lower IW content in the PMCyA. At a high water content, the methoxy oxygen in the shorter side chain of the HPx cannot effectively bind water compared to that in the PMCyA side chain. HPx side chains may have more room to contact with molecules other than water (e.g., proteins), causing experimentally less nonthrombogenicity of HPx than that of PMCyA. In summary, theoretical simulations successfully explained the difference in the effects of side-chain spacing and length in atomistic scale.

Isolation and Quantification of miRNA from the Biomolecular Corona on Mesoporous Silica Nanoparticles.

To understand the factors that control the formation of the biomolecular corona, a systematic study of the adsorption of several miRNAs shown to be important in prostate cancer on amine-functionalized mesoporous silica nanoparticles (MSN-NH2) has been performed. Process parameters including miRNA type, nanoparticle concentration, incubation temperature and incubation time were investigated, as well as the potential competition for adsorption between different miRNA molecules. The influence of proteins and particle PEGylation on miRNA adsorption were also explored. We found that low particle concentrations and physiological temperature both led to increased miRNA adsorption. Adsorption of miRNA was also higher when proteins were present in the same solution; reducing or preventing protein adsorption by PEGylating the MSNs hindered adsorption. Finally, the amount of miRNA adsorbed from human serum by MSN-NH2 was compared to a commercial miRNA purification kit (TaqMan®, Life Technologies, Carlsbad, CA, USA). MSN-NH2 adsorbed six times as much miRNA as the commercial kit, demonstrating higher sensitivity to subtle up- and downregulation of circulating miRNA in the blood of patients.