The penetration of a soft solid by a liquid jet, with application to the administration of a needle-free injection

Liquid jet injections have been performed on human skin in vivo and silicone rubber using Intraject needle-free injectors. The discharge characteristics of the liquid jet were measured using a custom-built test instrument. The experiments reveal that a high-speed liquid jet penetrates a soft solid by the formation and opening of a planar crack. The fluid stagnation pressure required for skin penetration decreases with increasing diameter of the liquid jet. These findings are consistent with the slow-speed penetration of a soft solid by a sharp-tipped punch. It is demonstrated that the Shergold-Fleck sharp-tipped punch penetration model [Shergold, O.A., Fleck, N.A., 2004. Mechanisms of deep penetration of soft solids. Proc. Roy. Soc. Lond. A 460, 3037-3058.] gives adequate predictions for the pressure required to penetrate a soft solid by a high-speed liquid jet.     

Jet injection into polyacrylamide gels: investigation of jet injection mechanics

Jet injectors employ high-velocity liquid jets that penetrate into human skin and deposit drugs in the dermal or subdermal region. Although jet injectors have been marketed for a number of years, relatively little is known about the interactions of high-speed jets with soft materials such as skin. Using polyacrylamide gels as a model system, the mechanics of jet penetration, including the dependence of jet penetration on mechanical properties, was studied. Jets employed in a typical commercial injector, (orifice diameter: 152 microm, velocity: 170-180 m/s) were used to inject fluid into polyacrylamide gels possessing Young's moduli in the range of 0.06-0.77 MPa and hardness values in the range of 4-70 H(OO). Motion analysis of jet entry into polyacrylamide gels revealed that jet penetration can be divided into three distinct events: erosion, stagnation, and dispersion. During the erosion phase, the jet removed the gel at the impact site and led to the formation of a distinct cylindrical hole. Cessation of erosion induced a period of jet stagnation ( approximately 600 micros) characterized by constant penetration depth. This stage was followed by dispersion of the liquid into the gel. The dispersion took place by crack propagation and was nearly symmetrical with the exception of injections into 10% acrylamide (Young's modulus of 0.06 MPa). The penetration depth of the jets as well as the rate of erosion decreased with increasing Young's modulus. The mechanics of jet penetration into polyacrylamide gels provides an important tool for understanding jet injection into skin.     

Intradermal immunization with novel plasmid DNA-coated nanoparticles via a needle-free injection device

A high population of dendritic cells in the skin makes intradermal (ID) immunization an attractive route. We sought to further enhance immune responses from a previously reported novel nanoparticle-based DNA vaccine delivery system by administering the system intradermally into mouse skin using Biojector 2000, a needle-free jet injection device. Two mouse studies were carried out. Balb/C mice (n=5-6) were immunized on day 0, 7, and 14 by subcutaneous injection or via the Biojector 2000 with pDNA alone (CMV-beta-galactosidase, 5 micro g), pDNA-coated nanoparticles, or beta-galactosidase protein (10 micro g) adjuvanted with 'Alum' (15 micro g). On day 28, mice were sacrificed and specific serum IgG and IgA titer, in vitro cytokine release, and cell proliferation of isolated splenocytes were determined. Similar to previous reports, in both mouse studies, SC immunization with pDNA-coated nanoparticles led to over a log increase in specific serum IgG titer as compared to immunization with pDNA alone. For pDNA alone, jet and SC injection did not result in significant differences in IgG titer. In contrast, for pDNA-coated nanoparticles, jet injection led to as high as a 20-fold enhancement in IgG titer over SC injection. In addition, jet injection of pDNA-coated nanoparticles enhanced the IgG titer by more than 200-fold over jet injection of pDNA alone. Also, jet injection of pDNA-coated nanoparticles resulted in significantly enhanced specific serum IgA titer. For in vitro cytokine release, immunization with pDNA-coated nanoparticles by jet injection enhanced IFN-gamma and IL-4 release over pDNA alone by 6- and 5-fold, respectively. SC injection of pDNA-coated nanoparticles also resulted in enhanced IFN-gamma and IL-4 release over pDNA alone although with less magnitude. Finally, immunization with pDNA-coated nanoparticles, by both jet injection and SC injection, led to improved splenocyte proliferation over pDNA alone. In conclusion, a combination of a novel cationic nanoparticle-based DNA delivery system with ID jet injection led to enhanced antibody production, Th-1/Th-2 balanced cytokine release, and enhanced splenocyte proliferation.     

Low-volume jet injection for efficient nonviral in vivo gene transfer

The transfer of naked deoxyribonucleic acid (DNA) represents an alternative to viral and liposomal gene transfer technologies for gene therapy applications. Various procedures are employed to deliver naked DNA into the desired cells or tissues in vitro and in vivo, such as by simple needle injection, particle bombardment, in vivo electroporation or jet injection. Among the various nonviral gene delivery technologies jet injection is gaining increasing acceptance because it allows gene transfer into different tissues with deeper penetration of the applied naked DNA. The versatile hand-held Swiss jet injector uses pressurized air to force small volumes of 3 to 10 μL of naked DNA into targeted tissues. The β-galactosidase (LacZ) reporter gene construct and tumor necrosis factor α gene-expressing vectors were successfully jet injected at a pressure of 3.0 bar into xenotransplanted human tumor models of colon carcinoma. Qualitative and quantitative expression analysis of jet injected tumor tissues revealed the efficient expression of these genes in the tumors. Using this Swiss jet-injector prototype repeated jet injections of low volumes (3–10 μL) into one target tissue can easily be performed. The key parameters of in vivo jet injection such as jet injection volume, pressure, jet penetration into the tumor tissue, DNA stability have been defined for optimized nonviral gene therapy. These studies demonstrate the applicability of the jet injection technology for the efficient and simultaneous in vivo gene transfer of two different plasmid DNAs into tumors. It can be employed for nonviral gene therapy of cancer using minimal amounts of naked DNA.     

An Innovative Needle-free Injection System: Comparison to 1 ml Standard Subcutaneous Injection

A needle-free delivery system may lead to improved satisfaction and compliance, as well as reduced anxiety among patients requiring frequent or ongoing injections. This report describes a first-in-man assessment comparing Portal Instruments’ innovative needle-free injection system with subcutaneous injections using a 27G needle. Forty healthy volunteer participants each received a total of four injections of 1.0 mL sterile saline solution, two with a standard subcutaneous injection using a 27G needle, and two using the Portal injection system. Perception of pain was measured using a 100-mm visual analog scale (VAS). Injection site reactions were assessed at 2 min and at 20–30 min after each injection. Follow-up contact was made 24–48 h after the injections. Subject preference regarding injection type was also assessed. VAS pain scores at Portal injection sites met the criteria to be considered non-inferior to the pain reported at 27G needle injection sites (i.e., upper 95% confidence bound less than +5 mm). Based on a mixed effects model, at time 0, accounting for potential confounding variables, the adjusted difference in VAS scores indicated that Portal injections were 6.5 mm lower than the 27G needle injections (95% CI ?10.5, ?2.5). No clinically important adverse events were noted. Portal injections were preferred by 24 (60%) of the subjects (P = 0.0015). As an early step in the development of this new needle-free delivery system, the current study has shown that a 1.0-mL saline injection can be given with less pain reported than a standard subcutaneous injection using a 27G needle.     

Flow and oxygen transfer in a plunging water jet system using inclined short nozzles and performance characteristics of its system in aerobic treatment of wastewater

For the plunging water jet system using inclined short nozzles, the flow characteristics such as the bubble penetration depth and the gas entrainment rate, which changed depending on the jet velocity, the nozzle diameter, the jet length, and the jet angle were first evaluated in an air-water system. A comparable investigation between our results and those of existing studies used the long nozzles on those characteristics revealed that both the bubble penetration depth and the gas entrainment rate differed depending on the nozzle length; that is, the nozzle-length-to-diameter ratio L(N)/D(N) and that of these characteristics the gas entrainment rate affected considerably by its magnitude and tended to be high when the nozzle of a large L(N)/D(N) ratio was used. It was also confirmed from the oxygen transfer experiments that the transfer efficiency at low jet velocities in the present water jet system was not inferior to the ones of other types of existing aeration systems; that is, the utilization of this jet aeration system to a high rate reactor for wastewater treatment or fermentation was sufficiently possible. The applicability of the plunging jet aeration method to microbial processes was then examined. As a typical example of microbial processes to be tested, the continuous treatment of an organic wastewater using activated sludge microorganisms was carried out, and the performance and related problem when this type of aeration system was applied to such a microbial process were investigated. Experimental results showed that, when viewed from the removal ability of dissolved organic matters, the plunging jet aeration system was capable of treating a wastewater of considerable high loading without the rate of oxygen transfer becoming the biooxydation-rate-limiting factor. Special attention was necessary for the choice of the liquid pump to be employed, however, due to the increased amount of fine suspended solids in the treated water caused by the shearing action between sludge flocks and pump blades.     

Genetic immunization by jet injection of targeted pDNA-coated nanoparticles

Genetic immunization strategies have largely focused on the use of "naked" plasmid DNA or the gene gun. However, there remains a clear need to further improve the efficiency and/or cost of potential DNA vaccines. The theoretical basis of our research is to rationally design genetic immunization methodologies for nanoparticle-based delivery systems of plasmid DNA, perhaps in combination with already commercially available needle-free devices, such as the Biojector 2000. These methodologies may both reduce the dose of pDNA required and enhance the breadth and depth of protective immune responses (i.e., humoral and cellular). The purpose of this article is to provide detailed experimental methods to (1) engineer and characterize pDNA-coated cationic nanoparticles (<100nm) directly from oil-in-water microemulsion precursors and (2) enhance both the breadth and depth of immune responses after immunization of mice with pDNA-coated nanoparticles by different routes of administration, including intradermal, using a needle-free jet injection device.     

Mechanical aspects of CO2 angiography

The aim of this paper is to clarify some physical–mechanical aspects involved in the carbon dioxide angiography procedure (CO₂ angiography), with a particular attention to a possible damage of the vascular wall.CO₂ angiography is widely used on patients with iodine intolerance. The injection of a gaseous element, in most cases manually performed, requires a long training period. Automatic systems allow better control of the injection and the study of the mechanical behaviour of the gas.CO₂ injections have been studied by using manual and automatic systems. Pressures, flows and jet shapes have been monitored by using a cardiovascular mock. Photographic images of liquid and gaseous jet have been recorded in different conditions, and the vascular pressure rises during injection have been monitored.The shape of the liquid jet during the catheter washing phase is straight in the catheter direction and there is no jet during gas injection. Gas bubbles are suddenly formed at the catheter’s hole and move upwards: buoyancy is the only governing phenomenon and no bubbles fragmentation is detected. The pressure rise in the vessel depends on the injection pressure and volume and in some cases of manual injection it may double the basal vascular pressure values.CO₂ angiography is a powerful and safe procedure which diffusion will certainly increase, although some aspects related to gas injection and chamber filling are not jet well known. The use of an automatic system permits better results, shorter training period and limitation of vascular wall damage risk.     

Ballistic impact of single particles into gelatin: experiments and modeling with application to transdermal pharmaceutical delivery

The impact and penetration of high speed particles with the human skin is of interest for targeted drug delivery by transdermal powder injection. However, it is often difficult to perform penetration experiments on dermal tissue using micron scale particles. To address this, a finite element model of the impact and penetration of a 2 μm gold particle into the human dermis was developed and calibrated using experiments found in the literature. Using dimensional analysis, the model was linked to a larger scale steel ball-gelatin system in order to extract key material parameters for both systems and perform impact studies. In this manner, an elastic modulus of 2.25 MPa was found for skin, in good agreement with reported values from the literature. Further gelatin experiments were performed with steel, polymethyl methacrylate, titanium, and tungsten carbide balls in order to determine the effects of particle size and density on penetration depth. Both the finite element model and the steel-gelatin experiments were able to predict the penetration behavior that was found by other investigators in the study of the impact of typical particles used for vaccine delivery into the human dermis. It can therefore be concluded that scaled up systems utilizing ballistic gelatins can be used to investigate the performance of transdermal powder injection technology.     

An elongation model of left ventricle deformation in diastole

A numerical method of the left ventricle (LV) deformation, an elongation model, was put forth for the study of LV fluid mechanics in diastole. The LV elongated only along the apical axis, and the motion was controlled by the intraventricular flow rate. Two other LV models, a fixed control volume model and a dilation model, were also used for model comparison and the study of LV fluid mechanics. For clinical sphere indices (SIs, between 1.0 and 2.0), the three models showed little difference in pressure and velocity distributions along the apical axis at E-peak. The energy dissipation was lower at a larger SI in that the jet and vortex development was less limited by the LV cavity in the apical direction. LV deformation of apical elongation may represent the primary feature of LV deformation in comparison with the secondary radial expansion. The elongation model of the LV deformation with an appropriate SI is a reasonable, simple method to study LV fluid mechanics in diastole.     

Hollow Microneedle Arrays for Intradermal Drug Delivery and DNA Electroporation

The association of microneedles with electric pulses causing electroporation could result in an efficient and less painful delivery of drugs and DNA into the skin. Hollow conductive microneedles were used for (1) needle-free intradermal injection and (2) electric pulse application in order to achieve electric field in the superficial layers of the skin sufficient for electroporation. Microneedle array was used in combination with a vibratory inserter to disrupt the stratum corneum, thus piercing the skin. Effective injection of proteins into the skin was achieved, resulting in an immune response directed to the model antigen ovalbumin. However, when used both as microneedles to inject and as electrodes to apply the electric pulses, the setup showed several limitations for DNA electrotransfer. This could be due to the distribution of the electric field in the skin as shown by numerical calculations and/or the low dose of DNA injected. Further investigation of these parameters is needed in order to optimize minimally invasive DNA electrotransfer in the skin.     

Distribution of Penicillin G in Serum and Tissue Cage Fluid in Cattle*

The penetration of penicillin into tissue cage fluid (TCF) in calves was studied after intravenous and intramuscular injection. The penicillin concentrations in TCF were lower than in serum and maximum was reached much later. Intravenous injection of benzyl-penicillin gave significantly higher levels in TCF than intramuscular injection. The penetration after procaine penicillin was very slow. The results showed that the serum peak rather than the area under curve determines the penetration of penicillin. Repeated intramuscular injections of benzylpenicillin and procaine penicillin caused an accumulation of penicillin in TCF. Similar levels were however reached by one single intravenous injection. The clinical counterparts to the used tissue cage model are abscesses. It was concluded that if high penicillin concentration are desireable in such foci, the drug must be given in a way that gives as high serum peaks as possible.     

Intratumoral low-volume jet-injection for efficient nonviral gene transfer

Jet-injection has become an applicable technology among other established nonviral delivery systems, such as particle bombardment or in vivo electroporation. The low-volume jet injector employed in this study uses compressed air to inject solutions of 1.5–10 μL containing naked DNA into the desired tissue. The novel design of this prototype makes multiple jet-injections possible. Therefore, repeated jet-injections into one target tissue can be performed easily. This jet-injector hand-held system was used for the direct in vivo gene transfer of plasmid DNA into tumors to achieve efficient expression of reporter genes (β-galactosidase, green fluorescent protein [GFP]) and of therapeutic genes (TNF-α) in different tumor models. The study presented here revealed the key parameters of efficient in vivo jet-injection (jet-injection volume, pressure, jet penetration, DNA stability) to define the optimal conditions for a jet-injection-aided nonviral gene therapy.     

Assessment of bull fertility using a mucus penetration test and a human chorionic gonadotrophin stimulation test

The relative predictive abilities of an in vitro mucus penetration test and a human chorionic gonadotrophin (hCG) stimulation test were compared for assessing bull fertility. Cervical mucus was collected from 22 Holstein cows and then stored in liquid nitrogen. Semen was collected from 13 Holstein bulls and evaluated for standard semen parameters. The mucus penetration test was performed with fresh ejaculates, and the results were expressed as the distance traveled by the vanguard spermatozoa during incubation at 38 degrees C for 10 min. Increases in plasma testosterone levels were determined by a ratio of testosterone concentration before and after hCG injection. Sperm motility and mucus penetration were significantly correlated with the conception rate. However, no significant correlation was confirmed between the increased plasma testosterone levels and conception rate. The results indicate that the mucus penetration test is an effective method for predicting the fertility of bulls.     

Microinjection of living adherent cells by using a semi-automatic microinjection system

Testing in vitro is an alternative to animal experimentation. The capillary pressure microinjection technique is a supporting technology for efficient in vitro testing. The main benefit of the technique is the possibility of injecting large molecules into a single living cell. The ultimate goal of the research discussed in this paper is to increase the cell survival rate in capillary pressure microinjection. A method to reliably evaluate cell survival rate is therefore needed. A three-phase evaluation process is presented in this paper. The first phase determines the success rate of the injection capillary to penetrate the cell membrane. The second phase studies the success rate of delivering the injection substance inside the cell, while the third phase studies cell survival after the microinjection. In addition to the three-phase evaluation process, this paper describes the initial results of penetration and injection tests performed by using a semi-automatic capillary pressure microinjection system developed by the research group. Three adherent cell lines, namely, retinal pigment epithelial cells, MCF-7 human breast cancer cells and SH-SY5Y neuroblastoma cells, were used in the experiments. The results of the penetration tests show that the average success rate of penetrating the cell membrane using the micromanipulator was 87%. The goal of the injection tests was to demonstrate the successful microinjection of living cells and to study the injection success rate. Fluorescein dextran was injected into MCF-7 cells, and preliminary results showed an injection success rate of 49%. In the survival tests, the neuronal cells were microinjected with KCl. During long-term observation after the microinjection, the microinjected cells first decreased their adhesion to the plate, but later adhered to the bottom of the plate and even grew some dendrites. In the next phase of the study, more tests will be performed in order to obtain a statistically reliable value for the survival rate.     

集成微管路电位分析及其在生态学研究中的应用

本文介绍了集成微管路电位分析原理,实验装置、分析特点及其在生态学研究中的应用。采用此微型装置测定了土壤、植物、水、血清、药物中的K~ 、Na~ 、Cl~-、pH、NH_3、NO_3~-、Ca~(2 )、Mg~(2 )、F~-、CN~-、I~-、S~-/Ag~ 、阿托品、东茛菪碱等,并和各种标准分析方法进行了比较,结果一致。鉴于集成微管路引入分析领域所提供的优点,它将在生态学研究中发挥重要作用。     

Spatially resolved diffuse imaging for high‐speed depth estimation of jet injection

We investigate the use of spatially resolved diffuse imaging to track a fluid jet delivered at high speed into skin tissue. A jet injector with a short needle to deliver drugs beneath the dermis, is modified to incorporate a laser beam into the jet, which is ejected into ex vivo porcine tissue. The diffuse light emitted from the side and top of the tissue sample is recorded using high‐speed videography. Similar experiments, using a depth‐controlled fiber optic source, generate a reference dataset. The side light distribution is related to source depth for the controlled‐source experiments and used to track the effective source depth of the injections. Postinjection X‐ray images show agreement between the jet penetration and ultimate light source depth. The surface light intensity profile is parameterized with a single parameter and an exponential function is used to relate this parameter to source depth for the controlled‐source data. This empirical model is then used to estimate the effective source depth from the surface profile of the injection experiments. The depth estimates for injections into fat remain close to the side depth estimates, with a root‐mean‐square error of 1.1 mm, up to a source depth of 8 mm.      

Steady state model for evaluation of external and internal mass transfer effects in an immobilized biofilm

A steady model for the evaluation of external liquid film diffusion and internal pore diffusion effects in an immobilized biofilm system under continuous mode of operation was developed. The model takes into account, substrate diffusion through external liquid film and biofilm. Average rate of substrate consumption in the biofilm was considered. The overall efficiency of the biofilm was mathematically represented by considering the combined effects of substrate penetration and substrate utilization in the biofilm. The model was illustrated using a case study of pyridine biodegradation in a rotating biological contactor immobilized with pyridine degrading microbial film. The model is able to effectively predict both internal and external mass transfer effects in an immobilized biofilm system.     

Multiparameter analysis and sorting of mammalian cells

An improved multisensor cell sorting instrument for quantitative analysis and sorting of cells has been developed. Cells stained with fluorescent dyes enter a flow chamber where cell volume, fluorescence, and light scatter sensors simultaneously measure multiple cellular properties. Cells then emerge in a liquid jet that is broken into uniform liquid droplets. Sensor signals are electronically processed in one of several ways for optimum cell discrimination and are displayed as pulse-amplitude distributions using a multichannel pulse-height analyzer. Processed signals activate cell sorting according to preselected parametric criteria by electrically charging droplets containing cells and electrostatically deflecting them into collection vessels. Illustrative examples of multiparameter cell analysis and sorting experiments using a model mouse tumor cell system, human and animal leukocytes, and cultured mammalian cells are presented.     

Vortex Formation with a Snapping Shrimp Claw

Snapping shrimp use one oversized claw to generate a cavitating high speed water jet for hunting, defence and communication. This work is an experimental investigation about the jet generation. Snapping shrimp (Alpheus-bellulus) were investigated by using an enlarged transparent model reproducing the closure of the snapper claw. Flow inside the model was studied using both High-Speed Particle Image Velocimetry (HS-PIV) and flow visualization. During claw closure a channel-like cavity was formed between the plunger and the socket featuring a nozzle-type contour at the orifice. Closing the mechanism led to the formation of a leading vortex ring with a dimensionless formation number of approximate ΔT*≈4. This indicates that the claw might work at maximum efficiency, i.e. maximum vortex strength was achieved by a minimum of fluid volume ejected. The subsequent vortex cavitation with the formation of an axial reentrant jet is a reasonable explanation for the large penetration depth of the water jet. That snapping shrimp can reach with their claw-induced flow. Within such a cavitation process, an axial reentrant jet is generated in the hollow cylindrical core of the cavitated vortex that pushes the front further downstream and whose length can exceed the initial jet penetration depth by several times.