Amount Of Bovine Serum Albumin Research Articles

An Amperometric Glucose Biosensor Based on Poly (Pyrrole‐2‐Carboxylic Acid)/Glucose Oxidase Biocomposite

AbstractA newly developed amperometric glucose biosensor based on graphite rod (GR) working electrode modified with biocomposite consisting of poly (pyrrole‐2‐carboxylic acid) (PCPy) particles and enzyme glucose oxidase (GOx) was investigated. The PCPy particles were synthesized by chemical oxidative polymerization technique using H2O2 as initiator of polymerization reaction and modified covalently with the GOx (PCPy‐GOx) after activation of carboxyl groups located on the particles surface with a mixture of N‐(3‐dimethylaminopropyl)‐N′‐ethylcarbodiimide hydrochloride (EDC) and N‐hydroxysuccinimide (NHS). Then the PCPy‐GOx biocomposite was dispersed in a buffer solution containing a certain amount of bovine serum albumin (BSA). The resulting biocomposite suspension was adsorbed the on GR electrode surface with subsequent solvent airing and chemical cross‐linking of the proteins with glutaraldehyde vapour (GR/PCPy‐GOx). It was determined that the current response of the GR/PCPy‐GOx electrodes to glucose measured at +300 mV vs Cl reference electrode was influenced by the duration of the PCPy particles synthesis, pH of the GOx solution used for the PCPy particles modification and the amount of immobilized PCPy‐GOx biocomposite. An optimal pH of buffer solution for operation of the biosensor was found to be 8.0. Detection limit was determined as 0.039 mmol L−1 according signal to noise ratio (S/N: 3). The proposed glucose biosensor was tested in human serum samples.

Controlled hydrothermal synthesis of strontium-substituted hydroxyapatite nanorods and their application as a drug carrier for proteins

Without the addition of any organic additives, both undoped hydroxyapatite (HAp) and different strontium (Sr)-substituted hydroxyapatite (SrHAp) samples with amounts from 1 to 20 mol.% were synthesized via hydrothermal route. The crystal texture, chemical functional group and microstructure were well characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and inductively coupled plasma (ICP), respectively. And the protein adsorption and release properties of bovine serum albumin (BSA) and lysozyme (LYS) were investigated on the samples to search for a well protein drug delivery vehicle. The results revealed that the pure HAp consisted of uniform nanobelts and all SrHAp samples had a rod-like morphology. The lattice parameters of SrHAp were larger than HAp, while they had similar crystal structure. The protein adsorption and release tests indicated that the incorporation of Sr into HAp lattice could increase the amounts of BSA and LYS adsorption. The BSA adsorption capacity of 1SrHAp was found to be 55.52 mg/g, which was about 14.64% higher than that of HAp. The 15SrHAp possessed the highest LYS loading amount of 90.54 mg/g, which was about three times that of HAp. And SrHAp exhibited sustained protein release capability.

Surface Functionalization of Ti6Al4V via Self-assembled Monolayers for Improved Protein Adsorption and Fibroblast Adhesion.

Although metallic biomaterials find numerous biomedical applications, their inherent low bioactivity and poor osteointegration had been a great challenge for decades. Surface modification via silanization can serve as an attractive method for improving the aforementioned properties of such substrates. However, its effect on protein adsorption/conformation and subsequent cell adhesion and spreading has rarely been investigated. This work reports the in-depth study of the effect of Ti6Al4V surface functionalization on protein adsorption and cell behavior. We prepared self-assembled monolayers (SAMs) of five different surfaces (amine, octyl, mixed [1:1 ratio of amine:octyl], hybrid, and COOH). Synthesized surfaces were characterized by Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy, contact angle goniometry, profilometry, and field emission scanning electron microscopy (FESEM). Quantification of adsorbed mass of bovine serum albumin (BSA) and fibronectin (FN) was determined on different surfaces along with secondary structure analysis. The adsorbed amount of BSA was found to increase with an increase in surface hydrophobicity with the maximum adsorption on the octyl surface while the reverse trend was detected for FN adsorption, having the maximum adsorbed mass on the COOH surface. The α-helix content of adsorbed BSA increased on amine and COOH surfaces while it decreased for other surfaces. Whereas increasing β-turn content of the adsorbed FN with the increase in the surface hydrophobicity was observed. In FN, RGD loops are located in the β-turn and consequently the increase in Δ adhered cells (%) was predominantly increased with the increasing Δ β-turn content (%). We found hybrid surfaces to be the most promising surface modifier due to maximum cell adhesion (%) and proliferation, larger nuclei area, and the least cell circularity. Bacterial density increased with the increasing hydrophobicity and was found maximum for the amine surface (θ = 63 ± 1°) which further decreased with the increasing hydrophobicity. Overall, modified surfaces (in particular hybrid surface) showed better protein adsorption and cell adhesion properties as compared to unmodified Ti6Al4V and can be potentially used for tissue engineering applications.

Bovine serum albumin-dependent photoelectrocatalytic oxidation of ascorbate on a cadmium sulfide/titanium dioxide electrode

The photoelectrochemical oxidation of bovine serum albumin (BSA) at a cadmium sulfide/titanium dioxide (CdS/TiO2) electrode and its influences on the photoelectrocatalytic oxidation of ascorbate (AA) have been investigated by combining a photocatalytic fuel cell. The UV-excited BSA/CdS/TiO2 electrode exhibits direct oxidation peaks related to tryptophan (Trp) and other amino acid residues. The oxidation products of Trp on CdS/TiO2 electrode exhibit a pair of well-defined quinonyl/hydroquinonyl-based redox peaks at the formal potential of 0.025 V (vs. SCE) controlled by surface-confined electrochemical processes. The BSA oxidation photocurrent linearly increases with increasing BSA or O2 concentration. The AA oxidation is dependent on the UV irradiation, BSA concentration and photoanode materials. An appropriate amount of BSA leads to a 58% increase in the photocurrent response of AA oxidation on the CdS/TiO2 electrode, and a 0.5-fold increase in the maximum power density of the proposed photocatalytic AA/O2 fuel cell employing palladium(II) porphyrin Pd(II)TCPP (TCPP = meso-tetrakis(4-carboxyphenyl)porphyrin) modified carbon felt cathode. The present results provide a new platform for evaluating the effects of serum albumin on the antioxidative action of AA in the absence and presence of UV irradiation.

High capacitance and long cycle-life of nitrogen doped reduced graphene oxide

The quality of chemically synthesized few-layered graphene, which is known as reduced graphene oxide (RGO) depends on the oxidation of graphite, effective exfoliation of graphite oxide and complete reduction of graphene oxide. Herein, we report the preparation of nitrogen doped RGO by a modified Hummer’s method using potassium manganate along with potassium permanganate to achieve improved oxidation of graphite and a small amount of bovine serum albumin as a dispersant to avoid restacking of graphene sheets. Besides reducing the agglomeration of graphene layers, bovine serum albumin also serves as a nitrogen dopant. The quality of as-prepared nitrogen doped RGO is examined by morphological and structural studies. While microscopic studies confirm the formation of thin, well dispersed RGO sheets, X-ray photoelectron spectroscopic studies confirm the doping of nitrogen in RGO. A specific surface area of 286 m2 g−1 is obtained for nitrogen doped RGO, which is mainly contributed by the basal planes and ordered mesoporosity of RGO. The capacitance properties of as-prepared nitrogen doped RGO without any conductive additive are evaluated by cyclic voltammetry and galvanostatic charge–discharge cycling. A specific capacitance of 142 F g−1 obtained at a current density 1 A g−1 is almost twice the specific capacitance obtained for commercial graphene platelet aggregates (75 F g−1). The rate performance of as-prepared nitrogen doped RGO is comparable to that of commercial graphene platelet aggregates. It is also found that nitrogen doped RGO electrode can be charged and discharged for at least 2000 cycles without fade in the capacitance.

Adsorption of BSA on carbon-coated Fe3O4 microspheres activated with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride

Carbon-coated Fe3O4 (Fe3O4/C) microspheres activated with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC) were prepared, characterized and applied to adsorb bovine serum albumin (BSA). The prepared magnetic microspheres had spherical core-shell structure with a uniform and continuous carbon coating coupled with activation by EDC, and possessed superparamagnetic characteristics. The experimental results showed that the adsorption amount of BSA on the EDC-activated Fe3O4/C (Fe3O4/C-EDC) microspheres was higher than that on the Fe3O4/C microspheres. The maximum adsorption of BSA on Fe3O4/C-EDC microspheres occurred at pH 4.7, which was the isoelectric point of BSA. At low concentrations (below 1.0 M), salt had no noticeable effect on BSA adsorption. The BSA adsorption of Fe3O4/C-EDC microspheres had a better fit to the Langmuir model than the Freundlich isotherm and Temkin isotherm model, and the kinetic data were well described by the pseudo-second-order model. The adsorption equilibrium could be reached within 20 min. High desorption efficiency (97.6%) of BSA from Fe3O4/C-EDC microspheres was obtained with 0.5 M Na2HPO4 (pH 9.4) as the desorbent.

Mutant Huntingtin Secretion in Neuro2A Cells and Rat Primary Cortical Neurons.

Quantitative analysis of proteins secreted from the cells poses a challenge due to their low abundance and the interfering presence of a large amount of bovine serum albumin (BSA) in the cell culture media. We established assays for detection of mutant huntingtin (mHtt) secreted from Neuro2A cell line stably expressing mHtt and rat primary cortical neurons by Western blotting. Our protocol is based on reducing the amounts of BSA in the media while maintaining cell viability and secretory potential, and concentrating the media prior to analysis by means of ultrafiltration.

Immobilization of graphene-derived materials at gold surfaces: Towards a rational design of protein-based platforms for electrochemical and plasmonic applications

This work is focused on the critical analysis of the non-covalent modification of a thiolated-gold surface with different grapheneous materials and the covalent attachment of bovine serum albumin (BSA) as a model protein. The main goal was to find a relationship between the nature and amount of the grapheneous nanomaterial, the amount of immobilized protein, and the electrochemical and plasmonic properties of the resulting platforms. The characterization of the grapheneous nanomaterials (graphene oxide (GO), GO modified with chitosan (CHIT), (GO-CHIT), and chemically reduced GO-CHIT (RGO-CHIT)) was performed by using FTIR, Raman, TGA, Dynamic light scattering (DLS), UV–Vis spectroscopy and ζ-potential measurements. The characterization of the thiolated-gold surfaces modified with the different nanomaterials and BSA was performed using surface plasmon resonance (SPR), cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and scanning electrochemical microscopy (SECM). The pH of the grapheneous materials dispersions demonstrated to be a critical parameter to control the assembly of the nanomaterials and the model protein at the gold surfaces and, consequently, the electroactivity and plasmonics of the resulting platforms. When using GO, the optimum pH is 8.00 while in the case of GO-CHIT and RGO-CHIT, pHs << pKa,CHIT are the most adequate. We demonstrated that in the case of our model system, if the detection method depends on the direct quantification of the amount of BSA immobilized at the platform (like SPR), the use of GO is the best option; while if the detection mode depends on the changes in the electrochemical response of a redox marker (like EIS), the selected grapheneous material should be RGO.

Fabrication of Mesoporous Silica Thin Film Platforms for Surface Reaction with Surface Plasmon Resonance

Mesoporous silica thin films were fabricated on gold substrates with a sol-gel method including a cationic surfactant. The interface of gold and silica thin films was fixed with a mercaptosilane. The surface roughness of the thin films and their grain sizes of silica were both increased with the elimination of the cationic surfactant and polyethylene glycol (PEG) modification on its surface. The surface reaction, adsorption of bovine serum albumin (BSA), was monitored with surface plasmon resonance (SPR). Although the adsorption amount of BSA at 1 mg/mL were 7.9 ng/cm2 on the mesoporous silica, the PEG modification can completely desorb BSA. The mesoporous silica thin films on gold substrates fabricated will be a good platform for analyzing surface reaction.

Comparative study of surface properties of Mg-substituted hydroxyapatite bioceramic microspheres

Mg-substituted hydroxyapatite (HAp) bioceramic microspheres were prepared by spray drying and subsequent processing at 1173, 1273 and 1373K. Influence of various Mg substitution levels (up to 0.84±0.10wt%) on physicochemical properties of the HAp bioceramic microspheres was evaluated. Obtained results were used for the elucidation of the compositional and structural characteristics of the microspheres in conjunction with adsorption of protein, namely, bovine serum albumin (BSA). The primary difference among the microspheres processed at various temperature was the presence or absence of the micropores (<2nm in diameter) and mesopores (between 2 and 50nm). Presence of the micro- and mesopores resulted in higher specific surface area (SSA), enhanced solubility, i.e., ion release, and, accordingly, increase in the amount of BSA adsorbed on the microspheres. Furthermore, the BSA adsorption capacity of the microspheres decreased with increasing Mg content despite of higher SSA.

Thin Layer Chromatographic Resolution of Some β-adrenolytics and a β2-Agonist Using Bovine Serum Albumin as Chiral Additive in Stationary Phase

Direct enantiomeric resolution of commonly used five racemic β-adrenolytics, namely, bisoprolol, atenolol, propranolol, salbutamol and carvedilol has been achieved by thin layer chromatography using bovine serum albumin (BSA) as chiral additive in stationary phase. Successful resolution of the enantiomers of all racemic β-adrenolytics was achieved by use of different composition of simple organic solvents having no buffer or inorganic ions. The effect of variation in pH, temperature, amount of BSA as the additive, and composition of mobile phase on resolution was systematically studied. Spots were visualized in iodine vapors. Native enantiomers for each of the five analytes were isolated and identified and their elution order was determined. The limit of detection was found to be 0.7, 1.2, 0.84, 1.6 and 0.9 μg (per spot) for each enantiomer of bisoprolol, atenolol, propranolol, salbutamol and carvedilol, respectively.

The Effect of Nano-ZnO Surface Wettability on Modulating Protein Adsorption

Although surface wettability plays a major role in regulating protein adsorption and nanostructured ZnO has shown great potential in various biomedical fields, few reports have examined the influence of nano-ZnO surface wettability on protein adsorption. Herein, we explored the adsorption behavior of bovine serum albumin (BSA) on the superhydrophilic, hydrophilic, hydrophobic and superhydrophobic nano-ZnO surfaces. The adsorption amount of BSA increased with increase of hydrophilicity because of increased adsorption sites on the hydrophilic surface. The protein adsorption was proved to occur along with the desorption and conformational changes by well-fitted kinetic adsorption curves with the Spreading Particle Model and Fourier transformation infrared spectral analysis. The rates of BSA adsorption and desorption increased with hydrophobicity of the ZnO surfaces, which was considered to be related with the energy barrier created by water bound to the ZnO surfaces via hydrogen bonding. The rate of conformational change varied in a complex way, which might be influenced by the surface wettability of ZnO and some other factors. The present work may open up a new avenue to design nano-bio interfacial materials for advanced biological study and clinical applications.

Effects of pore distribution of hydroxyapatite particles on their protein adsorption behavior

The relationship between protein adsorption on hydroxyapatite (HAp) particles and their surface structure was investigated. Because the various crystal planes of HAp have been reported to exhibit selective adsorption, numerous studies have focused on developing methods to control HAp morphology for selective adsorption. However, few studies have examined the systematic adsorption of proteins on the HAp particles. We firstly synthesized HAp particles under various aging times and mild reaction conditions intending to obtain HAp particles having various surface structures despite similar morphology, chemical composition, and crystallinity. The aging time affected the pore size distribution of the HAp particles. A peak indicating pores with a diameter of approximately 2.5 nm was observed in the pore size distribution plots of the HAp particles prepared using aging times of 48 h or less. The adsorption of proteins on HAp particles with different surface structures was studied. The bovine serum albumin (BSA) adsorption behavior was influenced by the presence of pores on the HAp surface. The amount of BSA adsorbed on the HAp particles aged 72 h having no pores was nearly 1.5 times that of the other HAp particles having pores. These results indicated that the pore size distribution of HAp particles is one of the most important factors in controlling their protein adsorption behavior.

Carboxymethyl-β-cyclodextrin grafted chitosan nanoparticles as oral delivery carrier of protein drugs

In this paper, the novel carboxymethyl-β-cyclodextrin grafted chitosan (CMCD-g-CS) nanoparticles were fabricated and their potential as oral delivery carrier of protein drugs was evaluated. The physicochemical properties of the prepared nanocarriers were characterized by Fourier transforms infrared spectroscopy, nuclear magnetic resonance, transmission electron microscopy and dynamic light scattering. Bovine serum albumin (BSA), a model protein drug, was loaded in prepared nanocarriers with ideal entrapment efficiency (EE) and loading content (LC). The drug release profiles of BSA loaded nanoparticles were studied in simulated gastric fluid (SGF), simulated intestinal fluid (SIF) and simulated colonic fluid (SCF). It was found that the drug loaded nanovehicles displayed a typical controlled sustained release profiles and the amount of BSA released from the nanocarriers was much higher in SIF and SCF than it in SGF. The research results suggested that the CMCD-g-CS nanoparticles had the potential as promising nanocarriers for oral delivery of protein drugs.

Adsorption of bovine serum albumin and urease by biochar

The application of biochar to soil improvement inevitably affects free soil enzymes. However, there is little information on the interaction of soil enzymes with biochar to our knowledge. We thus investigated the adsorption of bovine serum albumin (BSA) and urease onto two biochars from giant reed pyrolyzed at 300 and 600 °C (BCF300 and BCF600). The adsorption amount of BSA and urease on BCF300 and BCF600 was up to 45.6-209 mg/g and 75.3-808 mg/g, respectively, suggesting that the test proteins could be adsorbed onto the biochars effectively. The sorption rate of BSA and urease significantly decreased as the protein concentration increased, suggesting that their adsorption was nonlinear. For the same initial concentration (50 or 200 mg/L), the adsorption amount of BSA on the biochars was lower, only 25.9-60.5% of that of urease. The high specific surface area and hydrophobicity of the biochars may play important roles on the immobilization of the proteins by biochars. These findings will be helpful for better understanding the effects of biochar adding on the soil enzymes.

Silver nanoclusters-catalyzed luminol chemiluminescence for hydrogen peroxide and uric acid detection

In the present study, four kinds of bovine serum albumin (BSA) caped silver nanoclusters (Ag NCs) were prepared using different amount of BSA as template, respectively. The diameters of the four prepared BSA-Ag NCs were all less than 4nm which were obtained using high-resolution transmission electron microscopy (HRTEM). All of the BSA-Ag NCs showed catalytic activity in luminol-H2O2 chemiluminescent (CL) reaction. It was interesting that different CL kinetic curves were obtained in different BSA-Ag NCs catalyzed CL reaction. Ag NCs with less template exhibited slow and stable signals. The luminophors for all the cases were still 3-aminophthalate ion in an excited state (3-APA*). Mechanism studies showed that Ag NCs with less template molecules have higher affinity to H2O2 and are benefit to the generation of •OH and 1O2. Then, Ag NCs with 4mg/mL of BSA as template was applied to the detection of H2O2. Under the optimum experimental conditions, the linear dynamic range for H2O2 detection was from 0.14μM to 100μM with a detection limit of 0.016μM. By combining the urate oxidase-catalyzed oxidation reaction, CL detection of uric acid was realized. The linear range of uric acid detection was 2–100μM with a detection limit of 0.75μM. The relative standard deviation (RSD) of six replicates determination of 10μM uric acid was 5.1%. The proposed method has been applied to the detection of uric acid in diluted serum.

Detailed Study of BSA Adsorption on Micro- and Nanocrystalline Diamond/β-SiC Composite Gradient Films by Time-Resolved Fluorescence Microscopy

The adsorption of bovine serum albumin (BSA) on micro- and nanocrystalline diamond/β-SiC composite films synthesized using the hot filament chemical vapor deposition (HFCVD) technique has been investigated by confocal fluorescence lifetime imaging microscopy. BSA labeled with fluorescein isothiocyanate (FITC) was employed as a probe. The BSAFITC conjugate was found to preferentially adsorb on both O-/OH-terminated microcrystalline and nanocrystalline diamond compared to the OH-terminated β-SiC, resulting in an increasing amount of BSA adsorbed to the gradient surfaces with an increasing diamond/β-SiC ratio. The different strength of adsorption (>30 times for diamond with a grain size of 570 nm) coincides with different surface energy parameters and differing conformational changes upon adsorption. Fluorescence data of the adsorbed BSAFITC on the gradient film with different diamond coverage show a four-exponential decay with decay times of 3.71, 2.54, 0.66, and 0.13 ns for a grain size of 570 nm. The different decay times are attributed to the fluorescence of thiourea fluorescein residuals of linked FITC distributed in BSA with different dye-dye and dye-surface distances. The longest decay time was found to correlate linearly with the diamond grain size. The fluorescence of BSAFITC undergoes external dynamic fluorescence quenching on the diamond surface by H- and/or sp2-defects and/or by amorphous carbon or graphite phases. An acceleration of the internal fluorescence concentration quenching in BSAFITC because of structural changes of albumin due to adsorption, is concluded to be a secondary contributor. These results suggest that the micro- and nanocrystalline diamond/β-SiC composite gradient films can be utilized to spatially control protein adsorption and diamond crystallite size, which facilitates systematic studies at these interesting (bio)interfaces.

FTIR characterization and release of bovine serum albumin from bioactive glasses.

Bioactive glass has attracted substantial interest in orthopedics, but it has been less explored as a drug carrier. This study investigated the bovine serum albumin (BSA) release from bioactive 13-93B0 and 13-93B3 glasses. Glass disks (13-93B0 and 13-93B3; n = 5) were loaded with 4 mg of BSA and coated under different chitosan-coating conditions. The amount of BSA released in phosphate-buffered saline (PBS) was evaluated, and a degradation study was performed to find out the weight loss and pH of PBS. Secondary structures of BSA on 13-93B0 were characterized by Fourier transform infrared (FTIR) spectroscopy. One hundred percent protein release occurred by 24 hours for all 13-93B3 groups. However, chitosan coating delayed 100% release up to 72 hours in 13-93B0 groups. The 13-93B3 glass showed higher degradation rates than 13-93B0 regardless of chitosan-coating status. Multilayer and sandwich chitosan coatings further delayed BSA release from 13-93B0. FTIR analysis revealed that α-helical structure was the highest among all groups and significantly higher in the 2% sandwich chitosan coating group (32.0% ± 2.1%), compared with uncoated and 4% chitosan groups. Chitosan coating can delay the burst release of BSA from 13-93B0 glass and be a potential coating on bioactive glass for drug delivery purposes.

Efficient approach to enhance drug solubility by particle engineering of bovine serum albumin

The aim of this study was to investigate the use of bovine serum albumin (BSA) as a solubility enhancer for indometacin (IND) as a model drug. IND-BSA solid dispersions were prepared by both spray drying and freeze drying techniques using IND:BSA solution (20:1 Molar Ratio (MR)) and IND:BSA suspension (100:1 MR). The solid state of IND in solid dispersions was characterised by SEM, DSC and XRD. The aqueous solubility of IND in the presence of increased amounts of BSA was evaluated. Additionally, IND dissolution and release profiles were evaluated. IND in solid dispersions with BSA showed significantly higher solubility in water than that of the physical mixture of both. Enhancement factors of 24,000 and 100,000 were obtained for the solid dispersion formulated in 20:1 MR and 100:1 MR, respectively. Dissolution studies in-vitro indicated a significant increase in the dissolution rate of IND from solid dispersions compared to that of the free drug, with almost 95% of the drug dissolved in the first 5min. Furthermore, an immediate release of IND from BSA solid dispersions was shown. The potential use of albumin as solubility enhancer for poorly soluble drugs, particularly, for immediate release volume-limited dosage forms is reported.

Spin coating of polymer solution on polydimethylsiloxane mold for fabrication of microneedle patch

Since 1990 s, research and development of microneedles (MNs) for transdermal drug delivery (TDD) have been receiving great attention. Among various kinds of MNs, the dissolvable polymer MNs provide several attractive merits such as biocompatibility, biodegradability, and active and controlled release of drugs. Currently, the widely practiced approaches, i.e. evaporation and centrifugation, suffer from either relatively long processing time or tedious procedure. This project aims to develop and validate a new method, i.e. spin-coating process, to fabricate polymer MNs in a relatively simple and fast manner. First, the polydimethylsiloxane (PDMS) daughter mold replicated from the MNs array was used and bonded to the cleaned glass slide. The assembly was then placed on the spin coater, followed by dispensing the polymer solution and switching on the spin coater. It was found that, addition of trace amount of bovine serum albumin (BSA) in the polymer solution will facilitate formation of polymer film on PDMS surface by spin coating. Moreover, with the simple setup and procedures, the dissolvable polymer MNs with needle height up to 300 µm can be obtained.