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WPI's NanoFil: Injection of Sub-Microliter Volumes in Animal Research

Are you looking for a microliter or sub-microliter and high precision syringe that holds needles as small as 36 gauge (G), in addition to having the capability to connect to quartz tubing?

WPI’s NanoFil is the answer. We offer NanoFil syringes with NanoFil needles or the option to connect the NanoFil syringe to quartz tubing to use in research studies, mainly involving sub-microliter volume injections into animal tissues.

Why Select WPI’s NanoFil (Syringe and Needle) System?

Low Dead Volume

The dead volume of NanoFil's is minute or negligible (0.5 µl or less). Therefore, the oil backfilling, a process used for accurate low volume injection, is not required for use with a NanoFil. The injection of a low volume sample using oil is messy and poses the risk of contamination of the injected sample. Direct sample injection using the NanoFil is simpler and less messy, and most importantly omits the possibility of contamination caused by oil in critical applications, such as ophthalmology research.

Easily Switch Needles during Experiments

NanoFil does not use a Luer connector. Instead it has a patented gasket design that allows for needle exchanges during an experiment. For example, you can front fill the 10 µl NanoFil syringe using the large 26G needle provided. Then choose the appropriate small needle dimension suitable to inject at the specific tissue site. There is minimal to negligible loss of sample during switching of needles.

Variety of Syringe Injection Tip Options (Needles and Quartz Tubing)

The patented silicone gasket of NanoFil syringe lets you couple not only needles, but also quartz tubing. Flexible quartz capillaries used in Gas Chromatography (GC) and Capillary Electrophoresis (CE) can be coupled to the NanoFil syringe. Many types of tubings can be connected to the syringe provided the outer diameter (OD) of the tubing is close to, but not more than the inner diameter (ID) of the inside barrel (460 µm) of the NanoFil syringe.

The Nanofil can be coupled with our Retinal Pigment Epithelial (RPE) and Intra Ocular (IO) injection kits. This makes NanoFil versatile for a variety of applications.

Variety of NanoFil Needles Sizes (26-36G)

The replaceable needles used with the NanoFil are available with either blunt or beveled tip designs. The blunt tip is used for injection into soft tissue and when a uniform solution distribution is needed. The beveled style NanoFil needles are used for applications that involve the penetration through a tough tissue. Nanofil needles are offered in sizes of 26G to 36G (OD of 460 µm to 120 µm).

Generally, a smaller needle tip diameter is better to limit diffusion occurring at the needle tip. A 36G needle would be the best suitable needle to restrict the diffusion at the tip of the needle. Any possible error resulting from diffusion when using a 36G NanoFil needle is expected to be negligible. (The error would be in the sub-nanoliter range). Thus, the use of NanoFil needles can help you maintain better accuracy during the injection of microliter and sub-microliter volumes.

33 gauge:  This tip is similar to Hamilton’s 7762 and 7803 series removable needles in both tip length and outer diameter. However, our beveled tip version is shorter, more durable, and penetrates better due to the special tri-surface grinding technique. In the past, 33 gauge tips were the smallest size sold by other manufacturers and were frequently cited in literature. However, our new 35 gauge tip is much better for injections involving small animals, especially mice. Compared with Hamilton’s 33 gauge, 10 degree beveled tip, our 35 gauge 25 degree beveled tip can reduce the depth of penetration by almost 80%. The distance between the tip and the upper rim of the opening (dimension F on the drawing) is 348 microns for the 33 gauge tip. The distance for our 35 gauge tip is only 230 microns. In addition, the smaller tip size significantly reduces the required penetration force. In nearly all applications, a 33 gauge tip can be replaced with our 35 gauge tip and produce better results.

34 gauge: This is a transitional size between the 33 gauge and 35 gauge. If the 35 gauge is too weak and the 33 gauge is too large, this makes a good alternative.

35 gauge: This was the most popular and preferred tip of most scientists during our field trial. The combination of its strength, length, durability, and clogging resistance creates a balance with very little compromising of the individual properties. It is much smaller than the 33 gauge tip offered by other manufacturers. It is only slightly larger than the 36 gauge tip but is much stronger and less likely to be clogged. Samples can be directly loaded with this tip. Its 5 mm length is sufficient enough for almost all injection applications in mice.

36 gauge: This is the smallest tip that is commercially available. The tip is so small that it can be inserted into the opening of the 33 gauge needle tip. Because this is pushing the limits of what current technology can produce, there are some limitations to consider before using. Its thin diameter makes it necessary to limit its length to 2.5 to 3 mm in order to maintain a usable strength. Since the tip ID is in the 25 to 50 micron range, it is very easily clogged. Therefore, only well filtered solutions can be used. Depending on the viscosity of the sample, the user might also need to pre-load the syringe with a regular tip before switching to this tip for injection. We recommend using the 35 gauge tip instead of the 36 gauge unless it is absolutely necessary.

WPI’s Unique Beveled Needle Tip Design

• Efficient for Injection and Causes Less Tissue Damage – All WPI's NanoFil beveled needles have a unique 25° tri-surface bevel design as oppose to a standard 10° single-surface beveled needle design. WPI’s 25° tri-surface needle design creates the needle tip surface like a point, whereas a 10° single-surface bevel creates a tip surface like a blade. 
  

  
  WPI’s 25° tri-surface Beveled Needle Tip Design

  A 10° single-surface beveled needle requires a deeper penetration of the needle in order to reach and inject at a specific tissue location. A deeper penetration of the needle than required can cause more local tissue damage and excessive unwanted tissue response. WPI's unique 25° tri-surface beveled needle tip minimizes the possibility of causing the excessive tissue damage during injection. Thus, WPI’s beveled NanoFil needle, having two extra beveled surfaces, can inject efficiently, minimizing the extent of tissue damage occurring at the site of injection.

• Better Durability –Our NanoFil needle’s tri-surface 25° beveled tip design allows it to penetrate through a tissue surface and the needle tip encounters less physical resistance from the tissue during penetration. As mentioned before, the 25° tri-surface needle creates a pointed surface containing 3 blades as compared to 10° single-surface beveled needle. The single-surface beveled needle tip is more prone to dulling after or during tissue penetration. The pointed tip design of our NanoFil needle is less prone to dulling and remains functional longer.

Overall, NanoFil needles not only penetrate tissue efficiently, causing minimal tissue damage, but also last longer. WPI’s NanoFil system (syringe and needle) is a very popular product in research involving animal microliter and sub-microliter injections in animal tissues.

Tip Order Number	Guage	Needle O.D. “A” (µm)	Avg. Neelde I.D. “B” (µm)	Tip Length “C” (mm)	Total Length “D” (mm)	Shank O.D. “E” (µm)	Bevel Length “F” (µm)	Total Dead Volume (µL)
NF33BV-2	33	210	115	10	40	460	≈348	0.416
NF34BV-2	34	185	85	5	35	460	≈290	0.199
NF35BV-2	35	135	55	5	35	460	≈204	0.435
NF36BV-2	36	110	35	3	33	460	≈156	0.340
NF33BL-2	33	210	115	10	40	460	≈0	0.416
NF34BL-2	34	185	85	5	35	460	≈0	0.199
NF35BL-2	35	135	55	5	35	460	≈0	0.435
NF36BL-2	36	110	35	3	33	460	≈0	0.340
NF26BV-2	26	460	110	3	40	460		0.380

Tip Material: Stainless Steel

Recent Citations

• Goswami, Mayank, et al. "Novel window for cancer nanotheranostics: non-invasive ocular assessments of tumor growth and nanotherapeutic treatment efficacy in vivo." Biomedical optics express 10.1 (2019): 151-166.
• Di Scala, C., et al. "A new polymer-based approach for in vivo transfection in postnatal brain." Journal of neuroscience methods 311 (2019): 295-306.
• Günther, Anne, et al. "HCN4 knockdown in dorsal hippocampus promotes anxiety-like behavior in mice." Genes, Brain and Behavior 18.2 (2019): e1255.
• Mühlfriedel, Regine, et al. "Optimized Subretinal Injection Technique for Gene Therapy Approaches." Retinal Degeneration. Humana Press, New York, NY, 2019. 405-412.
• Lee, Joonyeup, et al. "Transient effect of mossy fiber stimulation on spatial firing of CA3 neurons." Hippocampus29.7 (2019): 639-651.

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