Objective To develop a reversed-phase high-performance liquid chromatography(RP-HPLC) method for the determination of residual phenylmethanesulfonyl fluoride(PMSF) content in recombinant virus-like particle(VLP) vaccine stock solution,and to verify the method for the determination of PMSF residues in recombinant VLP vaccine stock solution.Methods A RP-HPLC method for the determination of PMSF residues was developed by screening detection wavelength,flow rate,injection amount and chromatographic column.The specificity,linearity and range,limit of quantitation(LOQ),limit of detection(LOD),accuracy,precision and durability of the method were verified.The developed method was used to detect PMSF residues in three batches of recombinant hepatitis E vaccine stock solution.Results The RP-HPLC method was developed,with ChromCore 300 C18(4.6 mm × 250 mm,5 μm) as the chromatographic column at the column temperature of 25 ℃,the detection wavelength of 210 nm,the injection amount of 100 μL,0.1% trifluoroacetic acid(TFA)/water and0.1% TFA/acetonitrile as mobile phase at a flow rate of 1 mL/min,and the detection time of 18 min.The absorption peaks of PMSF control and vaccine stock solution containing PMSF appeared around 5.0 min,while the vaccine stock solution and stock solution buffer showed no absorption peak.There was a good linear relationship between the concentration of PMSF control and peak area in the range of 0-5.0 μg/mL,with R~2 of 0.999.The LOQ and LOD of this method was 0.250 μg/mL and 0.125 μg/mL,respectively.The recovery rates of PMSF control with high,medium and low concentrations were all between 90% and 110%.The relative standard deviations(RSDs) of retention time,peak height and peak area for the determination of instrument repeatability,sample repeatability and intermediate precision were all less than 5%.The RSDs of retention time,peak height and peak area were all less than 5% under the TFA concentration of 0.09%,0.1% and 0.11% at column temperature of 20,25 and 30 ℃.PMSF was not detected in the three batches of recombinant hepatitis E vaccine stock solution.Conclusion The developed RP-HPLC method has good specificity,linearity and durability,high accuracy and precision,and can be used to detect residual PMSF content in recombinant VLP vaccine stock solution.
Phenylmethanesulfonyl fluoride(PMSF) ; Reversed-phase high-performance liquid chromatography(RP-HPLC) ; Virus-like particle(VLP) vaccine

OBJECTIVES: This study aims to use 3D prin-ting technology based on the principle of stereo lithography apparatus (SLA) to shape dental lithium disilicate ceramics and study the effects of different slurry proportions on the microstructure and properties of heat-treated samples. METHODS: The experimental group comprised lithium disilicate ceramics manufactured through SLA 3D printing, and the control group comprised lithium disilicate ceramics (IPS e.max CAD) fabricated through commercial milling. An array of different particle sizes of lithium disilicate ceramic powder materials (nano and micron) was selected for mixing with photocurable acrylate resin. The proportion of experimental raw materials was adjusted to prepare five groups of ceramic slurries for 3D printing (Groups S1-S5) on the basis of rheological properties, stability, and other factors. Printing, debonding, and sintering were conducted on the experimental group with the optimal ratio, followed by measurements of microstructure, crystallographic information, shrinkage, and mechanical properties. RESULTS: Five groups of lithium disilicate ceramic slurries were prepared, of which two groups with high solid content (75%) (Groups S2 and S3) were selected for 3D printing. X-ray diffraction and scanning electron microscopy results showed that lithium disilicate was the main crystalline phase in Groups S2 and S3, and its microstructure was slender, uniform, and compact. The average grain sizes of Groups S2 and S3 were (559.79±84.58) nm and (388.26±61.49) nm, respectively (P<0.05). Energy spectroscopy revealed that the samples in the two groups contained a high proportion of Si and O elements. After heat treatment, the shrinkage rate of the two groups of ceramic samples was 18.00%-20.71%. Test results revealed no statistical difference in all mechanical properties between Groups S2 and S3 (P>0.05). The flexural strengths of Groups S2 and S3 were (231.79±21.71) MPa and (214.86±46.64) MPa, respectively, which were lower than that of the IPS e.max CAD group (P<0.05). The elasticity modulus of Groups S2 and S3 were (87.40±12.99) GPa and (92.87±19.76) GPa, respectively, which did not significantly differ from that of the IPS e.max CAD group (P>0.05). The Vickers hardness values of Groups S2 and S3 were (6.53±0.19) GPa and (6.25±0.12) GPa, respectively, which were higher than that of the IPS e.max CAD group (P<0.05). The fracture toughness values of Groups S2 and S3 were (1.57±0.28) MPa·m^0.5 and (1.38±0.17) MPa·m^0.5, respectively, which did not significantly differ from that of the IPS e.max CAD group (P>0.05). CONCLUSIONS The combination of lithium disilicate ceramic powders with different particle sizes can yield a slurry with high solid content (75%) and suitable viscosity and stability. The dental lithium disilicate ceramic material is successfully prepared by using 3D printing technology. The 3D-printed samples show a small shrinkage rate after heat treatment. Their microstructure conforms to the crystal phase of lithium disilicate ceramics, and their mechanical properties are close to those of milled lithium disilicate ceramics.
Printing, Three-Dimensional ; Dental Porcelain/chemistry* ; Ceramics/chemistry* ; Materials Testing ; Particle Size

The development of safe and effective carriers is crucial for improving the in vivo stability of siRNA drugs and facilitating their clinical translation. Chitosan (CS), a natural cationic polymer, shows great potential in nucleic acid drug delivery. To optimize the physicochemical properties of CS/siRNA nanoparticles (NPs) and increase their siRNA delivery efficacy, in this study, hyaluronic acid (HA) was added into CS to form stable complex NPs through electrostatic interactions. The HA component is able to target the CD44 receptors on the surface of tumor cells, facilitating efficient siRNA delivery. First, we systematically investigated the effects of the molecular weights and mass ratio of CS and HA on the physicochemical properties of CS/HA NPs. The results showed that at HA: CS mass ratios of approximately 5:5 and 6:4, the complex NPs exhibited small particle sizes, narrow size distribution, and high storage stability. Under similar conditions, the size of CS/HA NPs increased with the increase in the molecular weights of CS and HA. Based on these findings, suitable conditions were selected to prepare CS/HA NPs for siRNA delivery. Cell experiments demonstrated that the introduction of HA effectively reduced the cytotoxicity of the CS delivery system and enhanced the NP uptake. The CS/HA/siRNA NPs achieved 50% to 60% silencing of the luciferase gene in HeLa-Luc cells. CS/HA NPs formed smaller nanoparticles with siRNA than pure CS and mediated specific interactions with tumor cells via HA, leading to efficient siRNA delivery. These findings provide valuable insights into the construction of natural polymer composite nanoparticles for application in siRNA delivery.
Hyaluronic Acid/chemistry* ; Chitosan/chemistry* ; RNA, Small Interfering/administration & dosage* ; Nanoparticles/chemistry* ; Humans ; Particle Size ; HeLa Cells ; Hyaluronan Receptors

Bio-mineralization has emerged as a promising strategy to enhance vaccine immunogenicity. This study optimized the calcium phosphate (CaP) mineralization process of foot-and-mouth disease virus-like particles (FMD VLPs) to achieve high mineralization efficiency and scalability. Key parameters, including concentrations of Ca²⁺, HPO₄^2-, NaCl, and VLPs, as well as stirring speed, were systematically optimized. Stability of the scaled-up reaction system and immunogenicity of the mineralized vaccine were evaluated. Optimal conditions [25.50 mmol/L Ca(NO₃)₂, 15 mmol/L Na₂HPO₄, 300 mmol/L NaCl, 0.75 mg/mL VLPs, and 1 500 r/min] yielded CaP-mineralized VLPs (VLPs-CaP) with high mineralization efficiency, uniform morphology, and a favorable particle size. Scaling up the reaction by 25 folds maintained consistent mineralization efficiency and particle characteristics. Immunization in mice demonstrated that VLPs-CaP induced higher titers of specific antibodies and neutralizing antibodies than unmineralized VLPs (P < 0.05). Higher IgG2a/IgG1 ratio and enhanced IFN-γ secretion (P < 0.05) further indicated robust cellular immune responses. We establish a stable and scalable protocol for VLPs-CaP, providing a theoretical and technical foundation for developing high-efficacy VLPs-CaP vaccines.
Vaccines, Virus-Like Particle/immunology* ; Immunogenicity, Vaccine ; Calcium Phosphates/chemistry* ; Foot-and-Mouth Disease Virus ; Biomineralization ; Particle Size ; Animals ; Mice ; Antibodies, Neutralizing/blood* ; Antibodies, Viral/blood* ; Immunity, Cellular

Vaccination is a crucial strategy for the prevention and control of infectious diseases. Virus-like particles (VLPs), composed of structural proteins, have garnered significant attention as a novel type of vaccine due to their excellent safety and immunogenicity. However, similar to most vaccine antigens, VLPs exhibit insufficient thermal stability, which not only restricts the widespread application of vaccines but also increases the risk of vaccine inactivation. This study aims to enhance the stability and shelf life of VLPs derived from type A foot-and-mouth disease virus (FMDV) by employing vacuum freeze-drying technology. The optimal lyoprotectant formulation was determined through single-factor and combinatorial screening. Subsequently, the correlation between the immunogenicity of the freeze-dried vaccine and the content of FMDV VLPs was evaluated via a mouse model. The stability of FMDV VLPs before and after freeze-drying was further assessed by storing them at 4, 25, and 37 ℃ for varying time periods. Results indicated that the lyoprotectant formulation No.1, composed of 7.5% trehalose, 0.1% Tween 80, 50 mmol/L glycine, 1% sodium glutamate, and 3% polyvinylpyrrolidone (PVP), effectively preserved the content of FMDV VLPs during the vacuum freeze-drying process. The immunization trial in mice revealed that the levels of specific antibodies, immunoglobulin G1 (IgG1), interleukin-4 (IL-4), and neutralizing antibodies induced by freeze-dried FMDV VLPs were comparable to those induced by non-freeze-dried FMDV VLPs. The heat treatment results showed that the storage periods of freeze-dried FMDV VLPs at 4, 25, and 37 ℃ were significantly longer than those of non-freeze-dried FMDV VLPs. In conclusion, the selected lyoprotectant formulation effectively improved the stability of FMDV VLPs vaccines. This study provides valuable insights for enhancing the stability of novel subunit vaccines.
Freeze Drying/methods* ; Animals ; Foot-and-Mouth Disease Virus/immunology* ; Mice ; Vaccines, Virus-Like Particle/chemistry* ; Foot-and-Mouth Disease/immunology* ; Vacuum ; Drug Stability ; Mice, Inbred BALB C ; Viral Vaccines/immunology*

This study aims to establish a method for counting the viral particles in adenovirus vector-based vaccines. Nano-flow cytometry was employed to analyze the viral particles in adenovirus-based vector vaccines at the single-particle level. Monodisperse silica nanoparticles with a refractive index close to that of the virus were selected as the particle size standard to calculate the viral particle size, which was then compared with the results obtained from transmission electron microscopy (TEM) to determine the gating strategy. Subsequently, a particle count standard was employed to calculate the viral particle concentration. The established method demonstrated good linearity, accuracy, precision, and specificity. The results of determined viral particle concentration showed a good correlation with the infectious titer. Compared with the conventional OD₂₆₀ method, nano-flow cytometry can directly measure the viral particle concentration and indicate whether the sample has been disassembled according to changes in viral particle concentration and size, thus more accurately reflecting the actual infectious potency of the sample. The novel quantification method established in this study is capable of indicating the efficacy of adenovirus vector-based vaccines and provides effective technical support for the quality control of such products.
Adenoviridae/genetics* ; Genetic Vectors ; Flow Cytometry/methods* ; Virion/isolation & purification* ; Particle Size ; Nanoparticles ; Viral Vaccines

The study aims to explore the methods for preparing nanocomplexes of Prussian blue nanoparticles (PBNPs) with UNO peptide (UNO-PBNPs) and the functions of the nanocomplexes targeting M2-type macrophages in vitro. PBNPs were prepared by the hydrothermal synthesis method. Subsequently, the peptide UNO (CSPGAKVRC) targeting the mannose receptor was modified on their surface by a heterobifunctional coupling approach. The morphological characteristics of nanoparticles were observed by scanning and transmission electron microscopy. Additionally, their particle size, Zeta potential, and dispersion stability were assessed. The structural characteristics of nanoparticles were analyzed by X-ray diffraction and other techniques. The biological safety of the nanoparticles was evaluated by the CCK-8 assay and hemolysis experiments. Moreover, the targeting performance of UNO-PBNPs towards M2-type macrophages was assessed in vitro. The results showed that the synthesized UNO-PBNPs exhibited uniform cubic morphology, with an average particle size of (202.00±4.21) nm. They were negative charged, well dispersed, and stable. At concentrations ≤ 200 μg/mL, the synthesized UNO-PBNPs led to the hemolysis rate below 5%, demonstrating excellent biocompatibility. The laser confocal imaging results showed that after co-incubation with M2-type macrophages, the FITC-labeled UNO-PBNPs were effectively accumulated in the cells, presenting a distinct fluorescence signal. Quantitative analysis by flow cytometry showed that the intracellular mean fluorescence intensity (6 019.00±346.04) of UNO-PBNPs was higher than that (4 054.00±379.14) of unmodified PBNPs (P < 0.001). In summary, the UNO-PBNPs prepared in this study exhibited a targeting effect on M2-type macrophages, providing a potential method for targeted delivery of PBNPs in the tumor microenvironment and laying a foundation for the remodeling of the tumor immunosuppressive microenvironment.
Ferrocyanides/chemistry* ; Nanoparticles/chemistry* ; Macrophages/drug effects* ; Peptides/chemistry* ; Particle Size ; Animals ; Mannose Receptor ; Mice ; Lectins, C-Type ; Mannose-Binding Lectins ; Receptors, Cell Surface

In this experiment, self-assembled nanoparticles(SANs) were prepared by the pH-driven method, and Her-HCP SAN was constructed by using herpetrione(Her) and Herpetospermum caudigerum polysaccharides(HCPs). The average particle size and polydispersity index(PDI) were used as evaluation indexes for process optimization, and the quality of the final formulation was evaluated in terms of particle size, PDI, Zeta potential, and microstructure. The proposed Her-HCP SAN showed a spheroid structure and uniform morphology, with an average particle size of(244.58±16.84) nm, a PDI of 0.147 1±0.014 8, and a Zeta potential of(-38.52±2.11) mV. Her-HCP SAN significantly increased the saturation solubility of Her by 2.69 times, with a cumulative release of 90.18% within eight hours. The results of in vivo unidirectional intestinal perfusion reveal that Her active pharmaceutical ingredient(API) is most effectively absorbed in the jejunum, where both K_a and P_(app) are significantly higher compared to the ileum(P<0.001). However, the addition of HCP leads to a significant reduction in the P_(app) of Her in the jejunum(P<0.05). Furthermore, the formation of the Her-HCP SAN results in a notably lower P_(app) in the jejunum compared to Her API alone(P<0.001), while both K_a and P_(app) in the ileum are significantly increased(P<0.001, P<0.05). The absorption of Her-HCP SAN at different concentrations in the ileum shows no significant differences, and the pH has no significant effect on the absorption of Her-HCP SAN in the ileum. The addition of the transporter protein inhibitors(indomethacin and rifampicin) significantly increases the absorption parameters K_a and P_(app) of Her-HCP SAN in the ileum(P<0.05,P<0.01), whereas the addition of verapamil has no significant effect on the intestinal absorption parameters of Her-HCP SAN, suggesting that Her may be a substrate for multidrug resistance-associated protein 2 and breast cancer resistance proteins but not a substrate of P-glycoprotein.
Nanoparticles/metabolism* ; Polysaccharides/pharmacokinetics* ; Intestinal Absorption/drug effects* ; Animals ; Rats ; Particle Size ; Drugs, Chinese Herbal/pharmacokinetics* ; Male ; Rats, Sprague-Dawley ; Drug Carriers/chemistry* ; Drug Compounding ; Cucurbitaceae/chemistry*

With Glycyrrhizae Radix et Rhizoma-Gypsum Fibrosum drug pair as the research object, supramolecular chemistry of traditional Chinese medicine(TCM) was used to study differences between the compatibility of herbal medicine Glycyrrhizae Radix et Rhizoma with mineral medicine Gypsum Fibrosum and its main component CaSO_4·2H_2O, so as to preliminarily discuss the scientific connotation of compatibility of Gypsum Fibrosum in clinical application. A Malvern particle sizer, a scanning electron microscope(SEM), and a conductivity meter were used to observe and determine the physical properties such as microscopic morphology, particle size, and conductivity of Gypsum Fibrosum, CaSO_4·2H_2O, and water decoctions of them with Glycyrrhizae Radix et Rhizoma. An inductively coupled plasma optical emission spectrometer(ICP-OES) was employed to detect the inorganic metal elements in Glycyrrhizae Radix et Rhizoma-Gypsum Fibrosum and Glycyrrhizae Radix et Rhizoma-CaSO_4·2H_2O. Isothermal titration calorimetry(ITC) was conducted to quantify the interactions of Gypsum Fibrosum and CaSO_4·2H_2O with Glycyrrhizae Radix et Rhizoma. A Fourier transform infrared spectrometer(FTIR) was used to analyze the characteristic absorption peak change of Glycyrrhizae Radix et Rhizoma-Gypsum Fibrosum and Glycyrrhizae Radix et Rhizoma-CaSO_4·2H_2O. X-ray diffraction(XRD) was performed to determine the crystal structure and phase composition of Glycyrrhizae Radix et Rhizoma-Gypsum Fibrosum and Glycyrrhizae Radix et Rhizoma-CaSO_4·2H_2O. Further, glycyrrhizic acid(GA) was substituted for Glycyrrhizae Radix et Rhizoma to co-decoct with Gypsum Fibrosum, CaSO_4·2H_2O, and freeze-dried powder of their respective water decoctions. The results of XRD were used for verification analysis. The results showed that although CaSO_4·2H_2O is the main component of Gypsum Fibrosum, there were significant differences between their decoctions and between the decoctions of them with Glycyrrhizae Radix et Rhizoma. Specifically,(1) Both CaSO_4·2H_2O and Gypsum Fibrosum were amorphous fibrous. However, the particle size and conductivity were significantly different between the decoctions of CaSO_4·2H_2O and Gypsum Fibrosum alone.(2) Under SEM, Glycyrrhizae Radix et Rhizoma-CaSO_4·2H_2O was a hybrid system with various morphologies, while Glycyrrhizae Radix et Rhizoma-Gypsum Fibrosum presented uniform nanoparticles.(3) The particle sizes and conductivities of Glycyrrhizae Radix et Rhizoma-CaSO_4·2H_2O and Glycyrrhizae Radix et Rhizoma-Gypsum Fibrosum were significantly different and did not follow the same tendency as those of the decoctions of CaSO_4·2H_2O and Gypsum Fibrosum alone.(4) Compared with Glycyrrhizae Radix et Rhizoma-CaSO_4·2H_2O, Glycyrrhizae Radix et Rhizoma-Gypsum Fibrosum had stronger molecular binding ability and functional group structure change.(5) The crystal form was largely different between the freeze-dried powder of CaSO_4·2H_2O decoction and Gypsum Fibrosum decoction, and their crystal forms were also significantly different from those of the freeze-dried powder of Glycyrrhizae Radix et Rhizoma-CaSO_4·2H_2O and Glycyrrhizae Radix et Rhizoma-Gypsum Fibrosum decoctions. The reason for the series of differences is that Gypsum Fibrosum is richer in trace elements than CaSO_4·2H_2O. The XRD results of GA-Gypsum Fibrosum and GA-CaSO_4·2H_2O decoctions further prove the importance of trace elements in Gypsum Fibrosum for supramolecule formation. This research preliminarily reveals the influence of compatibility of Gypsum Fibrosum or CaSO_4·2H_2O on decoction phase state, material form, and crystal form, providing a basis for the rational clinical application of Gypsum Fibrosum.
Drugs, Chinese Herbal/chemistry* ; Calcium Sulfate/chemistry* ; Glycyrrhiza/chemistry* ; Crystallization ; Particle Size ; Medicine, Chinese Traditional ; Rhizome/chemistry*

Guided by the concept of quality by design(QbD), this study optimizes the calcination and quenching process of calcined Magnetitum and establishes the XRD characteristic spectra of calcined Magnetitum, providing a scientific basis for the formulation of quality standards. Based on the processing methods and quality requirements of Magnetitum in the Chinese Pharmacopoeia, the critical process parameters(CPPs) identified were calcination temperature, calcination time, particle size, laying thickness, and the number of vinegar quenching cycles. The critical quality attributes(CQAs) included Fe mass fraction, Fe~(2+) dissolution, and surface color. The weight coefficients were determined by combining Analytic Hierarchy Process(AHP) and the criteria importance though intercrieria correlation(CRITIC) method, and the calcination process was optimized using orthogonal experimentation. Surface color was selected as a CQA, and based on the principle of color value, the surface color of calcined Magnetitum was objectively quantified. The vinegar quenching process was then optimized to determine the best processing conditions. X-ray diffraction(XRD) was used to establish the characteristic spectra of calcined Magnetitum, and methods such as similarity evaluation, cluster analysis, and orthogonal partial least squares-discriminant analysis(OPLS-DA) were used to evaluate the quality of the spectra. The optimized calcined Magnetitum preparation process was found to be calcination at 750 ℃ for 1 h, with a laying thickness of 4 cm, a particle size of 0.4-0.8 cm, and one vinegar quenching cycle(Magnetitum-vinegar ratio 10∶3), which was stable and feasible. The XRD characteristic spectra analysis method, featuring 9 common peaks as fingerprint information, was established. The average correlation coefficient ranged from 0.839 5-0.988 1, and the average angle cosine ranged from 0.914 4 to 0.995 6, indicating good similarity. Cluster analysis results showed that Magnetitum and calcined Magnetitum could be grouped together, with similar compositions. OPLS-DA discriminant analysis identified three key characteristic peaks, with Fe_2O_3 being the distinguishing component between the two. The final optimized processing method is stable and feasible, and the XRD characteristic spectra of calcined Magnetitum was initially established, providing a reference for subsequent quality control and the formulation of quality standards for calcined Magnetitum.
X-Ray Diffraction/methods* ; Drugs, Chinese Herbal/chemistry* ; Quality Control ; Particle Size