Phosphate Buffer Concentration Research Articles

Organic pollutant degradation by UV/peroxydisulfate process: Impacts of UV light source and phosphate buffer

In recent years, ultraviolet (UV) based advanced oxidation processes have been extensively studied for degradation of refractory organic pollutants in water and wastewater, and selection of an appropriate UV light source is an important issue. In this study, bench-scale tests were conducted on a mini-fluidic photoreaction system (MFPS) to determine the degradation kinetics of methylene blue (MB) by UV/peroxydisulfate (UV/PDS) process equipped with a low-pressure UV (LPUV), vacuum UV (VUV)/LPUV, or medium-pressure UV (MPUV) mercury vapor lamp. Results indicate that MB degradation by UV/PDS with various light sources all followed the pseudo-first order kinetics, and the photon fluence-based rate constant (kp,λ′) had a descending order of: VUV/LPUV/PDS ≫ MPUV/PDS > LPUV/PDS. Moreover, it is noted that phosphate buffer (PB) notably inhibited MB degradation: the kp,LPUV′, kp,VUV/LPUV′ and kp,MPUV′ decreased by 35.0%, 44.9% and 37.5% with the PB concentration increasing from 0 to 20 mM, respectively. The maximal decrease in kp,VUV/LPUV′ was ascribed to a strong competition of PB for VUV photons. Thereafter, pilot-scale tests were conducted to evaluate the practical performance of UV/PDS in terms of the electrical energy consumption per order (EEO). It was found again that the VUV/LPUV lamp was the optimal light source in UV/PDS for organic pollutant degradation. This study helps optimize the UV/PDS process for its practical application to water and wastewater treatment.

A validated stability-indicating reversed-phase-HPLC method for dipyridamole in the presence of degradation products and its process-related impurities in pharmaceutical dosage forms.

In this study, we developed and validated a method to determine dipyridamole-related impurities in pharmaceutical dosage forms using the reversed-phase-HPLC technique. All impurities were separated on a YMC pack C8 (150 mm × 4.6 mm, 3.0 μm) analytical column using a suitable mobile phase. Mobile phase A was 10 mM concentration of phosphate buffer (pH adjusted to 4.7 by adding diluted orthophosphoric acid) and mobile phase B was buffer:acetonitrile:methanol (at the ratio of 30:40:30 v/v). The optimized chromatographic conditions used in the experiment were as follows: flow rate, 1.0 mL/min; injection volume, 10 μL and column temperature, 35°C. Chromatographic detection was performed at 295 nm. The stressed samples were analyzed for degradation under acidic, basic, peroxide, water hydrolysis, and physical degradation conditions. The proposed method was validated according to International Conference on Harmonization (ICH) guidelines, and found to be specific, linear, accurate and have a robust stability-indicating nature. The method showed excellent linearity from limit of quantification (LOQ) to 150% level of concentrations for all impurities. The correlation coefficient (r2 ) for all impurities was between 0.995 and 0.999. The recovery study was performed from LOQ to 150% level concentrations, with mean recovery values between 92.9% and 103.2%, respectively. The developed method can be used to determine dipyridamole and its relative impurities. The degradation and validated study results indicate its stability-indicating nature. Therefore, the method can be used in pharmaceutical research and development and quality control departments.

Hydrogen Peroxide Detection Using Prussian Blue‐modified 3D Pyrolytic Carbon Microelectrodes

AbstractA highly sensitive amperometric Prussian blue‐based hydrogen peroxide sensor was developed using 3D pyrolytic carbon microelectrodes. A 3D printed multielectrode electrochemical cell enabled simultaneous highly reproducible Prussian blue modification on multiple carbon electrodes. The effect of oxygen plasma pre‐treatment and deposition time on Prussian blue electrodeposition was studied. The amperometric response of 2D and 3D sensors to the addition of hydrogen peroxide in μM and sub‐μM concentrations in phosphate buffer was investigated. A high sensitivity comparable to flow injection systems and a detection limit of 0.16 μM was demonstrated with 3D pyrolytic carbon microelectrodes at stirred batch condition

Buffer capacity regulates the stratification of anode-respiring biofilm during brewery wastewater treatment

Improving the buffer capacity of the electrolyte can enhance the anode performance in bioelectrochemical systems (BESs). To elucidate the mechanism underlying the facilitated BESs performance, this study used three different anode biofilms cultured with different concentrations of phosphate buffer (5, 50 and 100 mM) to investigate the biofilm response, in terms of the spatial structure of metabolic activity and microbial community, to different buffer capacities. Results showed that the electrochemical activities of the anode biofilms positively correlated with the buffer concentration. The spatial stratification of metabolic activity and microbial community of the anode biofilms were regulated by the buffer capacity, and the spatial microbial heterogeneity of the anode biofilm decreased as the buffer concentration increased. With increasing buffer capacity, Geobacter spp. were enriched in both the inner and outer layers of the biofilm, and the inhibition of methanogens growth improved the COD removal attributed to anode respiration. Additionally, the stimulation of EPS production in biofilms played a role in increasing the electrochemical performance of biofilms by buffer improvement. This study first revealed the regulation of buffer capacity on the stratification of anode biofilm during brewery wastewater treatment, which provided a deep insight into the relation of biofilm structure to its electrochemical properties.

Hydrogen production during direct cellulose fermentation by mixed bacterial culture: The relationship between the key process parameters using response surface methodology

Dark fermentation is a promising method to produce hydrogen from lignocellulosic biomass. This study assessed the influence of temperature, phosphate buffer concentration and substrate concentration on direct hydrogen production form cellulose using response surface methodology. Mixed bacterial culture was successfully enriched on cellulose and used as an inoculum for hydrogen production. The model indicated that the highest cumulative hydrogen production (CHP) of 2.14 L H2/Lmedium could be obtained at 13.5 gcellulose/L, 79.5 mM buffer and 32.6 °C. However, hydrogen yield is then only 0.58 mol H2/molhexose due to low substrate conversion efficiency (SCE). Simultaneous optimization of CHP and SCE with desirability function approach resulted in the H2 yield of 2.71 ± 0.1 mol H2/molhexose and 93.8 ± 1.8% SCE at 3.35 gcellulose/L, 69 mM buffer and 32.9 °C. Phosphate concentration above 80 mM decreased H2 production, but had positive effect on cellulose consumption. The bacterial community analysis showed that Ruminiclostridium papyrosolvens was responsible for cellulose hydrolysis. Lachnoclostridium sp. was positively correlated with ethanol production at high phosphate buffer concentration, while Caproiciproducens sp. with caproate production at low buffer concentration. The obtained results opens the possibility of simultaneous hydrogen and caproate production from cellulosic substrates.

Control of retention mechanisms on an octadecyl-bonded silica column using ionic liquid-based mobile phase in analysis of cytostatic drugs by liquid chromatography

This study assesses the potential of using ionic liquids (ILs) as mobile phase additives to control the retention mechanism of four cytostatic drugs: doxorubicin hydrochloride (DOX), epirubicin hydrochloride (EPI), daunorubicin hydrochloride (DAU) and idarubicin hydrochloride (IDA). Chromatographic separations were performed on a C18 analytical column (Discovery C18 150 × 4.6 mm, 5 µm) using six IL anions and four methyl-substituted IL cations with different alkyl chain lengths (alone or with the additional methyl group on the aromatic ring), or with an allyl group added as a cationic substituent. Thus, a total of 17 different ILs were assessed. The aqueous formic acid solution and phosphate buffer were used to compare how mobile phase composition affected the behavior of the analyzed cytostatic agents in the presence of ILs. In addition, the impacts of IL concentration, phosphate buffer concentration, and phosphate buffer pH on the final results were also considered. The ability to change analyte retention without negatively impacting peak shape or analytical efficiency was also controlled via the tailing factor and number of theoretical plates. Based on the results, the tested ILs were classified as either effective or ineffective mobile phase additives for separation of anthracyclines and identification by LC-FL technique.

Physical and Electrochemical Characterization of Modified Graphite Nanoparticles-Phosphotungstic Acid-Nafion on Glassy Carbon Electrode for Bisphenol A Determination

A simple and rapid electrochemical sensor based on modified graphite nanoparticle with phosphotungstic acid and Nafion (GN–PTA–nafion) on glassy carbon electrode (GCE) has been developed for detecting bisphenol A (BPA). The GN was characterized using a scanning electron microscope (SEM) and X-ray diffractometer (XRD), while the modified GCE was characterized using differential pulse voltammetry (DPV) and cyclic voltammetry (CV). Several parameters such as GN concentration, scan rate, equilibrium time, and pH of phosphate buffer were optimized in this study. The GN–PTA–Nafion modified GCE that consists of graphite nanoparticle with a large surface area showed better and faster electron transfer, whereas the phosphotungstic acid (PTA) increased the sensitivity of the electrode for BPA detection. Good electrochemical performances for analyzing BPA, with a detection limit of 0.3995 mol L-1, as well as good reproducibility (RSD 2.51%) were obtained. The modified electrode showed that it had short analysis time, inexpensive and good sensitivity for BPA detection.

A Label-free DNA-based Fluorescent Sensor for Cisplatin Detection

Cisplatin, an anti-cancer drug, has been used extensively and has become a “gold standard” treatment for various types of cancer. However, overdosage has serious side effects. Thus, this drug should not be over-administered. The current study presents a label-free but sensitive fluorescent sensor for cisplatin detection based on G-quadruplex (GQ) and fluorescent dye Thioflavin T (ThT). In the absence of cisplatin, ThT binds to GQ, resulting in high fluorescence emission. In the presence of cisplatin, the GQ structure is destroyed after cisplatin–DNA adduct formation, leaving no binding scaffold for ThT, thereby causing a decrease in ThT fluorescence. The amount of cisplatin can be quantified from the changes in ThT fluorescence intensity. Parameters that affect the sensor performance were tested, including pH and concentration of potassium phosphate buffer, type of GQ, number of quartets, loop length, incubation time, and temperature. The sensor provided a linear dynamic range of 10–500 nM with limit of quantification at 10 nM. The sensor was successfully applied to detect cisplatin in urine samples from patients undergoing treatment with high accuracy (recoveries between 74 ± 14 and 112.8 ± 5.0%) and precision (relative standard deviations between 1.15% and 2.12%).

Trichosanthes dioica Roxb. prevents hepatic inflammation and fibrosis in CCl4-induced ovariectomized rats

Summary Plant-derived natural products have shown beneficial effects in many diseases associated with liver. The present study aimed to appraise the effects of Trichosanthes dioica (TD) peel extract on oxidative stress, inflammation as well as fibrosis exhibited by the ovariectomized rats in which hepatic damage had been induced by the administration of carbon tetrachloride (CCl4). The CCl4 administration in the ovariectomized rats elevated the plasma ALT, AST, and ALP level in comparison with the control while TD peel extract showed significant reduction of those activities. Besides, oxidative stress and lipid peroxidation also increased in CCl4-treated rats. TD peel extract significantly reduced the oxidative stress marker's concentration and improved the catalase and SOD activities in CCl4-administered ovariectomized rats. These results suggest that TD peel extract is capable of protecting the liver from CCl4induced damage through preventing oxidative stress, lipid peroxidation, inflammation, fibrosis and boosting the diminished cellular antioxidant defense.

Proton-Coupled Electron Transfer from Tyrosine in the Interior of a de novo Protein: Mechanisms and Primary Proton Acceptor.

Proton-coupled electron transfer (PCET) from tyrosine produces a neutral tyrosyl radical (Y•) that is vital to many catalytic redox reactions. To better understand how the protein environment influences the PCET properties of tyrosine, we have studied the radical formation behavior of Y32 in the α3Y model protein. The previously solved α3Y solution NMR structure shows that Y32 is sequestered ∼7.7 ± 0.3 Å below the protein surface without any primary proton acceptors nearby. Here we present transient absorption kinetic data and molecular dynamics (MD) simulations to resolve the PCET mechanism associated with Y32 oxidation. Y32• was generated in a bimolecular reaction with [Ru(bpy)3]3+ formed by flash photolysis. At pH > 8, the rate constant of Y32• formation (kPCET) increases by one order of magnitude per pH unit, corresponding to a proton-first mechanism via tyrosinate (PTET). At lower pH < 7.5, the pH dependence is weak and shows a previously measured KIE ≈ 2.5, which best fits a concerted mechanism. kPCET is independent of phosphate buffer concentration at pH 6.5. This provides clear evidence that phosphate buffer is not the primary proton acceptor. MD simulations show that one to two water molecules can enter the hydrophobic cavity of α3Y and hydrogen bond to Y32, as well as the possibility of hydrogen-bonding interactions between Y32 and E13, through structural fluctuations that reorient surrounding side chains. Our results illustrate how protein conformational motions can influence the redox reactivity of a tyrosine residue and how PCET mechanisms can be tuned by changing the pH even when the PCET occurs within the interior of a protein.

Use of hydrocarbons sludge as a substrate for the production of biosurfactants by Pseudomonas aeruginosa ATCC 27853.

The purpose of this study was to elucidate the capacity of a Pseudomonas aeruginosa strain to metabolize hydrocarbons sludge in the production of biosurfactants to fight against environmental threats. The performance of the treatment consisted in monitoring the inductive metabolism of the strain during 48h at a temperature of 37°C which constitutes an opportunity of treatment of various hydrocarbons contained in crude oil and spilled in the ecosystem to prevent pollution and damage. The results showed that a treatment rate of 96,8% and an emulsification index of 71.8% were obtained corresponding to a phosphate buffer concentration of 30mmol/L. The main role of the biosurfactants produced was to emulsify the medium and to absorb the oils contained in the hydrocarbons sludge. This allowed to stabilize hydrocarbon oils and favored the inductive metabolism of P. aeruginosa. Furthermore, physicochemical and Fourier transform infrared spectroscopy (FTIR) analysis showed that the produced biosurfactants were of rhamnolipid type. They showed promising surfactant properties, such as a strong reduction in the surface tension of water from 72 to 40.52mN/m, a high reactivity in the culture medium at pH7, a high osmotolerance up to 150g/L of salt, and a critical micellar concentration of 21mg/L.

Refolding with Simultaneous Purification of Recombinant Serratia marcescens Lipase by One-Step Ultrasonication Process.

A new lipase from Serratia marcescens SRICI-01 (Trx-SmL) was successfully overexpressed in Escherichia coli with thioredoxin (Trx) fusion tag. Intriguingly, the concentration of potassium phosphate buffer (KPB) showed significant impact on the aggregation state of Trx-SmL during ultrasonic disruption. The proportion of inclusion bodies increased dramatically with the increase of KPB concentration from almost completely soluble in 10mM KPB to insoluble in 200mM KPB. Based on this new finding, a novel method for refolding and purification of recombinant Trx-SmL was developed by one-step ultrasonication. The Trx-SmL was firstly precipitated in 200mM KPB, washed for three times, and subsequently subjected to ultrasonic process in 10mM KPB where refolding and purification occurred simultaneously. This established method was proved to be a straightforward, economical, and efficient purification approach to facilely obtain recombinant Trx-SmL protein with high purity (> 90%) and activity recovery yield (> 80%) from cell lysates. The application potential of the purified fusion Trx-SmL was further demonstrated by kinetic bioresolution of (±)-trans-3-(4-methoxyphenyl)glycidic acid methyl ester [(±)-MPGM] producing optically pure (-)-MPGM, a key intermediate for diltiazem, with an overall yield of 41.5% and ee of 99%.

First report on Chlorella vulgaris collagenase production and purification by aqueous two-phase system

Collagen is triple helical structured protein, which is undegradable by most proteases and reacts only with collagenases. These enzymes are applied and important in several commercial segments and the interest for new collagenases has only been increasing. Microalgae are not a very prominent source of enzymes but are extremely commercially attractive forms of life due to photosynthetic growth. Yet, the literature is absent on reports about algae collagenases and this work is the first report on Chlorella vulgaris collagenolytic enzyme production, purification and characterization. C. vulgaris was cultivated in autotrophic and mixotrophic conditions and the biomass used to obtain the cell extract. The autotrophic extract displayed a higher collagenolytic activity and was used for ATPS experimental design. Through 24-full factorial design, high collagenolytic activity was observed at pH 8.0, PEG molar mass of 1500 g/mol, PEG concentration of 12.5% (w/w) and phosphate buffer concentration of 15% (w/w). In these conditions, a purification factor of 10.79 was obtained for a partition coefficient of 23.74 with the collagenase retained in top PEG rich phase. Purified collagenase optimum activity was observed under pH 9 and 37 °C, displayed less gelatinolytic and caseinolytic activity, with higher collagenolytic activity with azocoll than crude extract, attesting this enzyme is a true collagenase. The collagenolytic activity was inhibited by EDTA, an indicative of a metallocollagenase.

Construction of a Hydrogel Pectin-Based Triglyceride Optical Biosensor with Immobilized Lipase Enzymes.

A novel and simple optical biosensor to detect triglycerides (TGs) has been successfully constructed by using pectin hydrogel membrane as the indicator pH and chromoionophore ETH 5294 (CI), with lipase as the catalyst. The enzymatic working system against TGs releasing H+ ions will affect the color absorbance of CI. The characterization results show that a TG biosensor has the optimum condition and sensitivity at the phosphate buffer concentration of 50 mM, pH 7, and enzyme loading of 60 μg. The biosensor works at the tripalmitin (TP) concentration range of 100–400 mg/dL. With the sensitivity of 0.001 (∆A/(mg/dL)), the biosensor response reaches stability after five minutes, and the limit of detection (LOD) of the TG optical biosensor is 15 mg/dL. Relative standard deviation (RSD) in a reproducibility test was 2.5%, with a 15-day lifespan.

Subcutaneous Injection of Drugs: Literature Review of Factors Influencing Pain Sensation at the Injection Site.

The subcutaneous administration route is widely used to administer different types of drugs given its high bioavailability and rapid onset of action. However, the sensation of pain at the injection site might reduce patient adherence. Apart from a direct effect of the drug itself, several factors can influence the sensation of pain: needle features, injection site, volume injected, injection speed, osmolality, viscosity and pH of formulation, as well as the kind of excipients employed, including buffers and preservatives. Short and thin needles, conveniently lubricated and with sharp tips, are generally used to minimize pain, although the anatomic injection site (abdomen versus thigh) also affects the sensation of pain. Large subcutaneous injection volumes are associated with pain. In this sense, the maximum volume generally accepted is around 1.5 ml, although volumes of up to 3 ml are well tolerated when injected in the abdomen. Injected volumes of up to 0.5–0.8 ml are not expected to increase substantially the pain produced by the needle insertion. Ideally, injectable products should be formulated as isotonic solutions (osmolality of about 300 mOsm/kg) and no more than 600 mOs/kg have to be used in order to prevent pain. A pH close to the physiological one is recommended to minimize pain, irritation, and tissue damage. Buffers are frequently added to parenteral formulations to optimize solubility and stability by adjusting the pH; however, their strength should be kept as low as possible to avoid pain upon injection. The data available recommend the concentration of phosphate buffer be limited to 10 mM and that the concentration of citrate buffer should be lower than 7.3 mM to avoid an increased sensation of pain. In the case of preservatives, which are required in multiple-dose preparations, m-cresol seems to be more painful than benzyl alcohol and phenol.Funding: Sandoz SA.

Separation and determination of six catechins in tea by pressurized capillary electrochromatography

An efficient pressurized capillary electrochromatography (pCEC) method has been successfully developed for the determination of six catechins in tea. The separation was performed on a reversed-phase EP-100-20/45-3-C18 capillary column (total length of 45 cm, effective length of 20 cm, diameter of 100 μm, ODS packing inside for 3 μm). The mobile phase ratio of organic phase, the concentration of phosphate buffer and sodium heptanesulfonate, separation voltage, and other experimental conditions were investigated and optimized. The mobile phase was 15 mM NaH2PO4 and 12 mM sodium heptanesulfonate (pH 3.0)/methanol (64:36) at a flow rate of 0.04 mL/min. Under optimal conditions including applied voltage of −4 kV and a UV detection wavelength of 230 nm, the six catechins in the tea were well separated. The calibration curves for the analytes had good linearity in the range of 8.02 μg/mL–202.13 μg/mL with a correlation coefficient of 0.9928–0.9997. The limits of detection (LOD) for the six catechins were 4.62 μg/mL–11.63 μg/mL (S/N = 3). The recoveries of the six catechins were 96.2%–108.4% with a relative standard deviation (RSD) between 0.78% and 4.51%. The method has been used for the determination of six catechins in tea samples with good results.

Mechanistic study of the nucleation and conformational changes of polyamines in presence of phosphate ions

Polyamine Phosphate Nanoparticles (PANs) have great potential for the delivery of large therapeutics, such as plasmids and/or siRNAs. The formation of PANs by complexation of Poly(allylamine hydrochloride) (PAH) and phosphate ions from Phosphate Buffer (PB) was studied here, and how it is affected by the presence of phosphate ions from PB and ionic strength. From Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DLS) the critical PB concentration for PANs formation was determined. Below this critical point, Small Angle X-ray Scattering (SAXS) studies revealed that small PAH-phosphate aggregates coexist with not complexed or weakly complexed polymer chains in solution and that the presence of the phosphate ions increases the Kuhn length of the polymer chains until that only spherical aggregates are present in solution. TEM, DLS and SAXS showed the increase of PANs size with ionic strength up to 250 mM NaCl. At higher NaCl concentrations, PANs disassemble into smaller aggregates. Isothermal Titration Calorimetry (ITC) showed that PAN formation is an exothermic process and the association of phosphates below the critical PB concentration is entropically controlled.

Size-dependent electrophoretic migration and separation of water-soluble gold nanoclusters by capillary electrophoresis.

Recently, water-soluble gold nanoclusters (AuNCs) have attracted more and more attention due to their unique properties. In this study, penicillamine-protected gold nanoclusters (Pen-AuNCs) were synthesized and initially fractionated by sequential size-selective precipitation (SSSP). The crude Pen-AuNCs and SSSP fractions were separated by capillary zone electrophoresis (CZE) with a diode array detector. The effects of key parameters, including the concentration of phosphate buffer, pH value and the ethanol content were systematically investigated. The separation of water-soluble poly-disperse AuNCs were well achieved at 30 mM phosphate buffer with 7.5% EtOH, pH 12.0, and applied voltage of 15 kV. The linear correlation between AuNCs diameter and mobility was observed. This finding provides an important reference for CE separation and product purification of water-soluble AuNCs or other nanomaterials.

High-concentration nitrogen removal coupling with bioelectric power generation by a self-sustaining algal-bacterial biocathode photo-bioelectrochemical system under daily light/dark cycle

High-concentration nitrogen removal coupled with bioelectric power generation in an algal-bacterial biocathode photo-bioelectrochemical system (PBES) was investigated. The PBES can self-sustaining operation with continuous power output under day/night cycle by alternately using photosynthetic dissolved oxygen and nitrate/nitrite as cathodic electron acceptors. The PBES generated a high maximum power of 110mw/m2 under illumination and relatively lower power of 40mw/m2 under dark. The bioelectricity generation was accompanied by high-concentration nitrogen removal in the algal-bacterial biocathode. The NH4N was removed completely within 120 h while maximum NO3N removal efficiency of 86% and maximum total nitrogen removal efficiency of 83% can be reached after 192 h at initial NH4N concentration of 314 mg/L and NO3N concentration of 330 mg/L. Combined processes of bioelectrochemical reduction and algal-bacterial interactions provided multiple approaches for nitrogen removal in the biocathode, including nitrifying using photosynthetic oxygen, bioelectrochemical denitrification using the cathode as electron donor, heterotrophic denitrification using photosynthetically produced dissolved organic matters as carbon source and algal-bacterial uptake. Accelerated nitrogen removal with simultaneously improved cathode performance was observed at high concentration of nitrogen and phosphate buffer due to enhanced algal activities for photosynthetic oxygen release and enhanced algal-bacterial interactions for nitrogen transformation. Addition of external organic carbon negatively affected nitrification and decreased cathode potential due to oxygen consumption by aerobic carbon oxidation but enhanced denitrification due to continuous release of high concentration of photosynthetically produced dissolved organic matters by alga. The PBEC was demonstrated as an energy-saving approach for high-strengthen nitrogenous wastewater treatment.

Investigating Recombinant Aciniform Silk Nanoparticles as Potential Drug Carriers and as Intermediates in Silk Fibrillogenesis

Spider silks form biomaterials including fibres, films, and nanospheres with excellent mechanical properties and biocompatibility. As such, silk materials have been investigated as a component of biomedical textiles for grafts and implants, as a scaffold for tissue regeneration, and as a drug delivery vehicle. Silk fibres generally form in vivo in a process where soluble proteins are forced through a narrowing spinning duct, giving rise to shear force. One theory of fibre formation is that silk proteins are stored in micellar form, with these micelles elongating while being forced together in the spinning duct, undergoing morphological and conformational transitions as shear forces are applied. Silk nanoparticles can be self-assembled, with concomitant or post-assembly incorporation of a variety of drug-like molecules into their interior. Here, we focus on the mechanism of formation of previously uncharacterized nanoparticles by recombinant aciniform spider silk proteins, their potential as drug carriers, and the role of these self-assembled species in the initial stages of fibre formation. The aciniform spidroin protein (AcSp1) from Argiope trifasciata consists of ≥14 repeat units of 200 amino acids (“W”, from wrapping silk) flanked by a non-repetitive N- and C-terminal domains. Recombinant proteins consisting of a single repeat (W1) spontaneously self-assemble into spherical micelle-like nanoparticles in potassium phosphate buffer. Insoluble W1 nanoparticles also form in highly concentrated phosphate buffer. Features of conformational transitions associated with nanoparticle formation from monomeric W1 are delineated here using tryptophan mutants of W1 through intrinsic tryptophan fluorescence and 19F NMR spectroscopy. Nanoparticle properties are correlated to these features using electron microscopy, dynamic light scattering, and Raman spectroscopy. Ultimately, reproducible and specific production of these nanoparticles will assist in the design and optimization of aciniform silk-based materials for biomedical and other materials applications.