CRISPR knockout uses wildtype Cas9 to create double-strand breaks. These are repaired by error-prone non-homologous end joining, which generates insertions or deletions that disrupt the reading frame and permanently ablate protein expression. CRISPRi uses a catalytically dead Cas9 (dCas9) fused to a transcriptional repressor domain such as KRAB. This silences a gene at the transcriptional level without altering the DNA sequence. CRISPRi effects are reversible once you remove the dCas9-KRAB construct.
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CRISPR Tools for Genome Engineering
Genome editing reagents including CRISPR-Cas9 kits, guide RNA clone collections, and donor templates for precise gene knockout, knock-in, and base editing.
CRISPR tools for genome engineering, from single-gene knockout to genome-wide screens
The toolkit spans single-gene editing through to genome-wide functional screens: Cas9 knockout, CRISPRa or CRISPRi transcriptional modulation, and safe-harbour knock-in of your defined transgene. Genome-wide pooled lentiviral CRISPR sgRNA libraries are also available when you need an unbiased screen. The right combination of reagents determines how cleanly and efficiently you reach your result.
Your core toolkit covers genome-wide sgRNA knockout libraries for human, mouse, chicken, and pig, as plasmid or lentiviral pools with tens of thousands of guides per species for loss-of-function screens at scale. Cas9 and dCas9 expression constructs are lentiviral plasmid or premade lentivirus, so you can select standard Cas9, the CRISPRa dCas9 variants for transcriptional activation, or CRISPRi dCas9 variants for transcriptional repression, including selected doxycycline-inducible variants for your temporal control.
Safe-harbour knock-in donor vectors targeting the AAVS1 locus support HDR-mediated stable integration of your transgene. CRISPR sgRNA cloning vectors and genomic cleavage detection kits complete your single-gene editing workflow, from guide delivery through to editing confirmation. Custom lentiviral sgRNA cloning is available if your guide is not in the catalogue. RNA interference tools for transient or stable gene silencing are covered separately in the RNA Interference & Small RNAs category.
Choose the approach by how permanent the modification needs to be.
- Stable gene knockout. All-in-one lentiviral constructs carry Cas9 and sgRNA on the same plasmid, or you can pair a cell line stably expressing Cas9 with a separate single or dual sgRNA construct. Confirm knockout efficiency and functional loss by genotyping and protein or phenotype assays before expanding the clone.
- Transcriptional silencing without DNA cleavage. CRISPRi dCas9 constructs handle this. dCas9-KRAB and dCas9-DNMT3A versions are available.
- Transcriptional activation. CRISPRa dCas9 activator constructs handle this: dCas9-VPR and dCas9-TET1CD versions are available.
- Stable knock-in at your defined locus. Safe-harbour donor vectors target the AAVS1 locus for this. AAVS1 is a widely used candidate safe-harbour locus. Expression and genomic impact remain cell-type and construct dependent, so verify them in the chosen cell type.
- Unbiased genome-wide screen. Genome-wide pooled lentiviral sgRNA knockout libraries covering the human or mouse genome support this, and you can combine them with next-generation sequencing of guide representation to identify the genes controlling any screenable phenotype.
- Verifying Cas9 activity before editing. Fluorescent reporter activity assays confirm active Cas9 in your specific cell line before you commit to the full editing experiment. SaCas9-compatible reporter variants are also available.
- Custom guide not in catalogue. You can order custom sgRNA cloning for single or dual guide designs, with optional Cas9 co-expression in the same construct.
- Transient or stable gene silencing. RNA interference tools (siRNA, shRNA, microRNA) are available in the RNA Interference & Small RNAs category.
Applications
Target validation and loss-of-function studies
CRISPR-Cas9 knockout builds isogenic lines for oncology and rare-disease targets. You confirm loss by genotyping and phenotype assay.
Reversible transcriptional modulation
CRISPRa and CRISPRi switch genes on or off without cutting the DNA sequence, useful when full knockout would be lethal to your cell.
Stable transgene integration
Safe-harbour knock-in at AAVS1 places a transgene at a defined genomic locus for predictable, stable expression via an HDR donor vector.
Unbiased genome-wide screens
Pooled lentiviral sgRNA libraries drive phenotypic screens in cancer lines, immune cells, and other cell models. You read out by next-generation sequencing.
Custom guide design
You can order single or dual sgRNA cloning for targets outside the standard catalogue, with optional Cas9 co-expression, extending the core CRISPR-Cas9 vector and library range.
Cas9 activity validation
Fluorescent reporter assays confirm active Cas9 in your cell line before a full edit, especially useful before a screen with gRNAs against many genes.
Product Catalog
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CRISPR/Cas9 Gene Knockout Constructs
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CRISPR sgRNA Cloning & Control Vectors
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CRISPR/Cas9 sgRNA Libraries
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Cas9 & dCas9 Expression Constructs
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Cas9 & dCas9 Activity Assays
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CRISPR-mediated Editing Detection
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CRISPR/Cas9 Safe Harbor Knock-in
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Frequently asked questions
CRISPR-based approaches act at the DNA or chromatin level and can achieve high-efficiency functional loss. RNAi instead degrades mRNA and typically achieves 70 to 95 percent knockdown, with variable residual expression. CRISPR effects are generally more durable, while siRNA is faster to deploy for transient experiments.
Off-target profiles differ between the two approaches, so orthogonal validation using both methods strengthens functional conclusions. RNAi tools are covered in the RNA Interference & Small RNAs category.
A safe-harbour locus is a candidate genomic site where transgene integration is less likely to disrupt endogenous gene expression or cause adverse phenotypes. AAVS1 sits in intron 1 of the PPP1R12C gene on chromosome 19, and it is a widely used candidate safe-harbour locus in human cells. Expression level and genomic impact remain cell-type and construct dependent, so verify them in the chosen cell type. Rosa26 serves a similar purpose in mouse cells.
A single guide RNA (sgRNA) guides Cas9 to a specific genomic locus. The sgRNA matches the target DNA sequence next to a protospacer adjacent motif (PAM). Cas9 then creates a blunt-ended double-strand break at the target.
The cell repairs the break mostly by error-prone non-homologous end joining. This generates small insertions or deletions that often disrupt the reading frame. Editing can produce in-frame, mosaic, or off-target outcomes, so confirm functional loss by genotyping and protein or phenotype assays.
Select sgRNAs that target the early exons of your gene of interest, near the start codon. This maximises the chance that indels cause loss of function. Use validated on-target activity scores and off-target prediction tools to rank candidates. Avoid sgRNAs with stretches of four or more consecutive thymidines, which can prematurely terminate U6-driven transcription.
The protospacer adjacent motif (PAM) is a short DNA sequence immediately downstream of the sgRNA target site. Cas9 needs it for binding and cleavage. SpCas9, the most commonly used variant, requires an NGG PAM on the non-template strand. Variant Cas9 proteins such as SaCas9, Cas12a, and engineered SpCas9 variants recognise different PAM sequences. This expands the range of targetable genomic sites.
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