In situ protein synthesis: cost-effective and reproducible cell-free arrays

Nucleic Acid Programmable Protein Arrays (NAPPA) offer a cost-effective and highly reproducible solution to cancer and autoimmune researchers involved in biomarker profiling and drug discovery.

The challenge

Manuel Fuentes of the Cancer Investigation Centre (CIC), Salamanca was fortunate to collaborate with researchers at Harvard Medical School in developing Nucleic Acid Programmable Protein Arrays (NAPPA). By eliminating the need for recombinant protein production and purification, NAPPA offers a cost-effective and highly reproducible solution for biomarker and drug discovery in tumour and autoimmune pathologies. Having generated results by high-medium density immunoassays in array format, the team were using a Genetix instrument to pin-spot nucleic acids for translation to proteins in situ. The contact-printed arrays lacked reproducibility, displayed cross-contamination and were slow to produce.

The need for speed

Principles behind NAPPA insisted that cDNA and capture antibodies are involved in a master mix which has to be printed within a short time window. Critical success factors meant the current instrument was no longer fit for purpose (Table 1).

Critical Success FactorResult with Genetix printer
SpeedThe short timeframe in which both samples were to be
deposited meant that a maximum of 20 slides could be
printed in each run
ReproducibilitySamples must be printed homogenously to ensure equal
protein content. The contact approach did not offer
satisfactory reproducibility
A minimum of 10 µg of costly sample was required to print
only 20 slides
ReliabilitySpots must be free of cross contamination

Table 1: Critical success factors against results with Genetix printer

The Arrayjet solution

Figure 1: Homogeneity of sample distribution compared between contact pin-spotter (left) and Arrayjet printer (right)

Arrayjet’s non-contact inkjet technology produces spots of noticeably improved morphology compared with pin-spotting systems (Figure 1). As a result, each spot translated to a comparable quantity of protein for reliable data acquisition.

Not only is it more reliable, Arrayjet’s “on-the-fly” method is also the fastest available on the market, enabling deposition of up to 640 features per second. Sample volume requirements are vastly reduced and print runs are largely automated freeing up valuable scientist time.

Transfer to the Arrayjet platform fully satisfied all critical success factors, exceeding customer expectations (Table 2).

Critical Success FactorArrayjet SolutionBenefit
Speed“On-the-fly” printingHigh-density slides printed without compromising sample
ReproducibilityInstruments and components with CV values <5%Comparable protein quantities
translated on each spot
Sample conservationJetSpyder™ liquid
handling device
1.3 µL sample aspiration prints
hundreds of slides
ReliabilityIntegrated wash stationPrint head and JetSpyder™ do not
contribute to contamination
Table 2: Critical success factors addressed by Arrayjet technology


Arrayjet’s high-throughput printing can be adapted to suit a variety of applications, including but not limited to:

  • Antigen discovery
  • Host-pathogen interaction screening
  • Biomarker screening
  • Epitope mapping
  • Antibody validation
  • Small molecule library screening
  • Hybridoma screening
  • Gene expression profiling

Offering both an in-house bioprinting service and a range of five scalable instruments, Arrayjet remain open to any novel screening ideas that test their technology even further.

SpeedPrinting time reduced fourfold leaving scientists free to conduct research
ReproducibilityFivefold increase in slide production
Sample conservationSample volume demands reduced tenfold
ReliabilitySignificant financial savings associated with automation, printing speed and sample conservation
Table 3: Summary of benefits of technology transfer to Arrayjet platform from contact printing
“Transfer to Arrayjet technology has had huge benefits for our cancer research and biomarker discovery. Our team can now produce 100 slides in a working day, using just 1 µg of cDNA per gene of interest. The automated process enables us to focus fully on our research knowing arrays will be printed reliably and reproducibly every time.”
Manuel Fuentes, Scientific Researcher at Cancer Investigation Centre

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