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Microinjection uses either a metal needle or a glass micropipette to inject small liquid volumes. For example, genetic material may be inserted into a living cell, a drug introduced into an eye or brain, or fluid injected into a muscle. Typically, microinjection is performed under a microscope. A stereotaxic setup may be required.

WPI offers a variety of pumps along with special syringes, stereotaxic frames, glass capillaries and needles. Here we will highlight our microinjection pumps. The setup you choose depends on the size of injection aliquots, the volume to be injected and the size of needle or glass tip chosen. The products described below are listed in order by the smallest volume they can inject. See the comparison chart below or the related post links at the bottom.

Pressure Injectors

WPI's new generation of pressure microinjectors are quickly replacing the very popular legacy line of pnuematic valve PicoPumps Pressure Injectors. The three new injectors facilitate any type of...more

Surgical Loupes help to alleviate eye strain by enlarging the image when you are working on tiny subjects or conducting precision operations. They are portable and easier to use than a surgical microscope. However, they are not created equal, and choosing the pair that's right for you is important to your satisfaction.

See Selection

Factors Involved in Choosing Loupes

Choosing the correct surgical loupes for your application involves several factors, including resolution, working distance, field of view, depth of field,  magnification, weight and interpupillary distance. These terms are defined below.

Ideally, you want the lowest magnification that is suitable for your application. As a general rule, the lower the magnification, the greater the depth of field and field of vision. Likewise, the longer the working distance, the greater the field of view. The larger your field of view, the less you need to turn your head. This reduces eye strain and fatigue. It is also important...more

The barbed tubing assortment kit contains over 250 items. All the items are pictured on a grid below. The darker lines in the image grid represent centimeters, and the smaller ones are 2.5 mm apart.

Profile B Microelectrodes

These electrodes are sold in packages of 10.

Stretch receptors are specialized fibers that are in parallel to the fibers in muscle. The receptors stretch as the muscle is lengthened, and they generate action potentials. The frequency of these action potentials is proportional to the length of muscle stretch and the position of the muscle. Through sensory nerve fibers from the stretch receptors, the action potentials and their frequency provide feedback to the central nervous system that will modulate reflex responses and motor control of the muscle.

Setup

For these studies, the whole muscle and the nerve that innervates it are isolated from the organism. A muscle and its nerve, like the Soleus, is isolated and placed in the cuvette of an SI-MT or SI-HTB muscle research system. The muscle is positioned so that the myoneural junction (the place where the nerve innervates the muscle) is on the top side of the muscle. The ends of the muscle are attached to a transducer and a motor through the tissue holders, and the end of the nerve...more

Abstract

Concentrations of DNA in solution (31µg/mL and 688µg/mL) were measured with a spectrometer and UV/VIS light source in a DIPUV-Mini. Due to the 2mm pathlength, use of a DIPUV-Mini does not require a pre-measurement dilution within this concentration range, thus a potential source of error was eliminated.

Experimental Procedure

Standard solutions of DNA (Sigma D1626) were prepared gravimetrically using 18.2MΩ/cm ultrapurified water as a solvent. Solutions were prepared between 0.0µg/mL and 687.6µg/mL.

Measurements were taken in triplicate using a DIPUV-Mini. The DIPUV-Mini was connected to a UV/VIS light source (WPI #D4H).

Data were collected in 1nm increments across the full range of the instrument (190nm-720nm). The instrument was configured such that reference measurements yielded an 80% total intensity. All measurements utilized 18.2MΩ/cm ultrapurified water as a reference solution.

 Results

Experimental results are presented in Table 1:

Abstract

Concentrations of DNA in solution (31µg/mL and 561µg/mL) were measured with a spectrometer and UV/Vis light source in a cuvette. A 2mm pathlength cuvette does not require a pre-measurement dilution within this concentration range, thus a potential source of error was eliminated. Although a 2mm cuvette has a total internal volume of 0.7mL, only 350µL is required to obtain an accurate measurement.

Experimental Procedure

Standard solutions of DNA (Sigma D1626) were prepared gravimetrically using 18.2MΩ/cm ultrapurified water as a solvent. Solutions were prepared between 0.0µg/mL and 561.1µg/mL.

Measurements were taken in triplicate using a 2mm cuvette (WPI #CUV2102-1) in a standard cuvette holder. An appropriate cuvette spacer (WPI #89342)allowed for consistent placement of the cuvette within the holder. The cuvette holder was attached via two 500µm SMA-terminated fiber optic cables to a UV/Vis light source (WPI #D4H).

Data were collected in 1nm increments across the full...more

Cuvettes come in a variety of shapes and sizes, but one of the most important specifications of a cuvette is its Z-dimension. The Z-dimension of an instrument (cuvette holder or spectrometer) is the distance from the bottom of the cuvette chamber floor to the center of its light beam (see image). A cuvette’s Z-dimension must match the Z-dimension of the instrument with which it will be used.

Each manufacturer designs its instruments with a specific Z-dimension. Common Z-dimensions include 8.5 and 15mm, and sometimes 20mm. When purchasing small volume cuvettes, the correct Z-dimension becomes critical. Matching the Z-dimension of the cuvette to the Z-dimension of the instrument ensures that the light beam passes through the center of small samples.The table below shows the standard Z-dimension of the spectrometer sample compartments for many manufacturers.

The Nanoliter injector is a micro-processor controlled injection system that uses direct piston displacement. The collet assembly (exploded view) is shown in the image below. The glass pipette fits into the white, plastic sleeve (spacer). When the collet is screwed in place securely, the black rubber washers are compressed and hold the glass firmly in place.

Nanoliter 2000

A side view of the assembled Nanoliter injector is shown below.

Nanoliter 2010 

As the plunger is depressed, it pushes into the glass to expel the liquid in the pipette. Eventually, the diameter of the plunger matches that of the glass, and the plunger cannot expel any more liquid. If the plunger continues to press on the tip of the pipette, the pipette could crack or become dislodged from the plastic sleeve (spacer) inside the collet assembly. If that happens, the Nanoliter will begin to leak.

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